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Experience and Experiment: A Comparison of Zabarella's View With Galileo's in De MotuAuthor(s): Charles B. SchmittSource: Studies in the Renaissance , Vol. 16 (1969), pp. 80-138Published by: The University of Chicago Press on behalf of the Renaissance Society of

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Experience and Experiment: A Comparison of

Zabarella's View with Galileo's in De Motu*

'Quoad congeriem vero, conficimus historiam non solum naturae liberae ac solutae

(cum scilicet illa sponte fluit et opus suum peragit), qualis est historia coelestium, mete-

ororum, terrae et maris, mineralium, plantarum, animalium; sed multo magis naturae

constrictae et vexatae; nempe, cum per artem et ministerium humanum de statu suo

detruditur, atque premitur et fingitur.'

Francis Bacon, Novum Organum (I620), 'Distributio operis, pars tertia'

'Experimentum est experientia, quae versatur circa facta naturae, quae nonnisi inter-

veniente opera nostra contingunt.'

Christian WolfE, Psychologia empirica (I732)

I. INTRO DU CTION

NE of the tendencies which clearly marked the intel-

g\ lectual development ofthe seventeenth century was an

fl A79 k increasing emphasis on experience.1 In philosophy

progressively from Gassendi to Locke; in science there

emerged ever more clearly a definable'experimental

method', which was progressively refined from Francis Bacon to New-

ton. By the end of the seventeenth century the classic works illustrating

these tendencies had appeared and set the trend for much of eighteenth-

century intellectual activity. The first editions, of Newton's Principia in

* This paper is partly an outgrowth of research carried out with the aid of Grant No.

3 809, Penrose Fund, American Philosophical Society. The generosity of this assistance is

gratefully acknowledged. In one form or another it has been read on the following occa-

sions: (I) 4 April I967, to the Columbia University Seminar on the Renaissance; (2) 24

May I968, to the Seminar on Methodology at University College, London; and (3 ) 5 July

I968, to the British Society for the History of Science, Summer Meeting at Leeds Uni-

versity. In preparing it I have benefited greatly from the many helpful suggestions, criti-

cisms, and comments of a number of scholars, especially the following: William F. Ed-

wards, Neal W. Gilbert, Donald R. Kelley, Paul Oskar Kristeller, Edward P. Mahoney,

J. R. Ravetz, Edward Rosen, William R. J. Shea, and Charles Webster.

1 I do not mean to imply that this was the only tendency in I7th-century thought or

even the dominant one, but merely to indicate that it was one of a number of approaches

to knowledge and understanding which became increasingly important in the course of

the century. For an example of a very different tendency which manifested itself at the

same time see Charles B. Schmitt, 'Perennial Philosophy: From Agostino Steuco to

Leibniz',Journal of the History of Ideas, xxvrs (I966), 505-532.

[ 80 ]




CHARLES B. SCHMITT

I687 and of Locke's Essay in I690, mark, in one sense, the beginnings of

a new era but, in another sense, the cultnination of an old one.

If this twofold movement of empiricism in philosophy and of experi-

mentalism irl sciellce took shape in the course of the seventeenth century,

what, we might ask, were the roots from which it sprarlg? What was

the situation say, a hundred years before the publicatio1l of the afore-

mentioned works of Locke arld Newton? More specifically, what role

did experience of the external world play in philosophical and sciel1tific

thought at the close of the sixteenth century?

A number of attempts have been made to trace the origills of experi-

mental methodology to events significantly before the seventeenth cen-

tury.2 These attempts have brought to our attention arl imposirlg array

of historical facts and have endeavored to explain these facts by a variety

of theoriese but none has attained anything like a universal acceptance.

Needless to say numerous difficulties and complicatiorls are encountered

whenever one tries to trace the origi1ls of any important intellectual

movemerlt. This is particularly true with regard to 'experimerltal

method for there does not seem to be a general agreement as to how

far such a methodology was a domirlant factor in the seventeenth-

century 'scientific revolution' or to what extent a key figure such as

Galileo practiced such an 'experimental method'.

Although unquestionably not the only factor involved, it might be

supposed that some clarificatiorl can be gained regarding this problem

through a careful analysis of just how important notions such as 'ex-

perience' and 'experiment' have functioned ill various corltexts, among

different schools, witllirl various historical periods, and in different dis-

ciplines. We certalnly find frequerlt recourse to 'experierlce' arld 'es-

periment' from antiquity onward, but this in itself is rlo indication that

2 of the large literature we might cite the following: R. Caverni, Storia deZ metodo

sperif7lentate ilx Italia (Florence, I89I-I8g8); Alexander Bruno Hanschmann, Bernard

Palissy: der Wii11stler, NczJurforscher, zzd Scllrftsteller, als Vater der indllktiven WVissensstlafts-

methode des Bacon von VerMlax7l (Leipzig, I903 ); Lynn Thorndike, History of Magic and Enc-

perif7letal Science (8 vols., New Yorka I923-I958); Raoul Carton, L'expetrience physiqxe

che;z Ftoger Bacon (Paris, I924); J. H. Randall, Jr., 'The Development of Scientific Method

in the School of Padua', Joltralal of the History of Ideas I (I940), I77-206 [reprinted in a

more definitive form in Randall's The School of lr'adua and the Emergence of Modern Science

(Padua, I96I),pp. I5-68]; A. C. Crombie, Wobert Grosseteste and the Origins of Experimental

Science (Oxford, I953); William A. Wallace, T/e Scientfic Methodology of Theodoric of

Fireiberg (Fribourg, IgSg); D. E. Gershenson and D. A. Greenberg, Anancagoras and the

BirtZa of Scientific Method (New York, I964); Angelo Valdarini, II metodo sperimentale da

Aristotele a Galileo, 3rd ed. (Bologna, I920).




82 TWO TERMS IN ZABARELLAAND GALILEO

all who have made such references have actually been practitioners of

an 'experimental method'. A major desideratum in this regard would

be to have a comprehensive study of the changing roles which 'experi-

etlce' and 'experiment' have played in the development of Western

thought, what meanings the terms have taken on under various circum-

stances, and what relation 'experience' and 'experiment' have had to

other sources of knowledge.

In the present paper I hope to make at least a small contribution to

this objective by analyzing the use of these notions in the writings of

two thinkers whose works seem crucial for the interpretation of the

backgrounds of seventeenth-century philosophical and scientific thought.

The two men whom I propose to study with regard to their conceptions

of'experience' and experiment' are Iacopo Zabarella (I533-I589) and

the young Galileo Galilei (I564-I642). Although such a choice lllay

seem arbitrary, it can, to some extent, be justified. A good deal of in-

terest has been focused upon Zabarella's importance, especially since

John Herman Randall's important article,3 and in methodological mat-

ters he seems to have been without a doubt the most acute and most in-

fluential of the Italian Renaissance Aristotelians.4 Galileo, of course,

emerged as a central figure in science during the first decades of the

seventeenth cetltury and whatever light can be shed upon him is of

prlmary lmportance.

It would seem to be more meaningful to compare and contrast Gali-

lco with Zabarella, than with the fourteenth-century Aristotelians as has

been done several times previously. Although it may be argued that

Zabarella was merely repeating what hundreds of his Aristotelian pred-

ecessors had said, such is not the case. The precise way in which the

sixteenth-century Aristotelians diSer from those of the fourteenth cen-

tury cannot be appropriately discussed here. In any event, it ras the late

sixteenth-century Aristotelians against whom Galileo rebelled; and it

3 'The Development of Scientific Method . . .', in Tlle sciloot of Padua and tlle Emer-

gCl1CC of Moder11 Scicnce, pp. I5-68. All further references will be to this edition, unless

otherwise noted.

4 The most recent student of I6th-century logic as a whole also points out Zabarella's

importance: 'Der bedeutendste dieser italienischell Aristoteliker ulld zweifellos der

Hohepunkt der Paduaner Schule ist Zabarella, eincr der scharfsimligstell und klarsten

Logiker aller Zeiten.' Wilhelm Risse, Die Logik der Nezjzeit: I. Baald, 1500-1640 (Stutt-

gart-Bad Cannstatt, I964), 278. See also William F. Edwards, The Logic of Iacopo Zaba-

rella (1533-1589) (Ncw York: Columbia University Dissertation, I960) and Pcter Peter-

sen, Gefcllicllte der aristotelischen Philosophie islt protestantischen Delltschlaald (Leipzig, I92I).




CHARLES B. SCHMITT

8 3

would seem sensible to compare their teachings to his, if we are to un-

derstand how he diSered from them and why his 'science' came ulti-

mately to replace theirs. Although thirteenth- and fourteenth-century

scholastic ideas as well as those of Averroes and of the Greek com-

mentators may be in the background of Zabarella this does not di-

rectly concern us in the present discussion. What does concern us here,

above all else, is how the youthful Galileo's attitude toward 'experience'

and 'experiment' compared with that of a prominent Aristotelian of

W 11S tlmO.

According to Randall reiterating a position originally developed by

Ernst Cassirer5 Zabarella, and the methodological tradition which he

sums up in his voluminous writings on logic, clearly points the way,

methodologically speaking, to Galileo.6 Cassirer, and Randall follow-

ing him, both admit that mathematics, which later played such an im-

portant role in Galileo's methodology, is completely lacking in Zaba-

rella's formulation.7 The great importance of mathematics ill Galileo's

sscience,' which has recently been shown so conclusively by Koyre and

others, would seem to put even a greater distance between Zabarella

5 Das Erkenntnisproblem in der Philosophie und Wissenschaft der neueren Zeit, 2nd ed.

(Berlin, IgII-Ig23), I, I36-I43. See also P. P. Wiener, 'The Tradition behind Galileo's

Methodology, Osiris, I (I936), 733-746, at 74I.

6 Cassirer, op. cit., I, I39: 'Mit dieser BegrifEsbestimmung der Erkenntnis aber weist

Zabarella bereits deutlich auf Galilei voraus. Auf ihn deutet nicht nur die Scheidung von

''kompositiver'' und "resolutiver" Methode, sondern vor allem die tiefere und reinere

Abgrenzung von popularer Beobachtung und wissenschaftlicher Erfahrung .... Alle

diese Ausfuhrungen sind von Galileis Methodenlehre, in der wir sie vollig gleichlautend

wiederfulden werden, nur durch einen einzigen Zug getrennt, der allerdings entscheidend

ist.' Randall, op. cit., p. 27: 'It is possible to trace step by step in rather beautiful fashion the

gradual elaboration of the Aristotelian method, in the light of the medical tradition, from

its first discussion in Pietro d'Abano to its completed statement in the logical controver-

sies of Zabarella, in which it reaches the form familiar in Galileo and the seventeenth-

century scientists.'

7Cassirer,op.cit.,I,I3g-I40:'DieRolle,diederMathematikinder beweisendenIn-

duktion" zukommt, wird von Zabarella nirgends begriffen: die Beispiele, auf die er sich

fur seine neue Grundanschauung beruft, sind nicht der exakten Wissenschaft, die erst in

vereinzelten Ansatzen vorlag, sondern der Metaphysik und Naturlehre des Aristoteles

entnommen.' Randall, op. cit., 65: 'There is but one element lacking in Zabarella's for-

mulation of method: he did not insist that the principles of natural science be mathemati-

cal, and indeed drew his illustrations largely from Aristotle's biological subject matter.'

Incidentally, one must use all ofthe redactions of Randall's article to get a comprehensive

picture of his view. Neal W. Gilbert, 'Galileo and the School of Padua', Jourllal of the

History of Pllilosophy, I (I963), 223-23I, at 227n4, has pointed out one change made by

Randall in a later version of the article, but there are others, as, for example, the curious

one discussed below in n. 57.





and Galileo as far as 'scientific rnethod' is concerned. Moreover, Neal

W. Gilbert has recelltly argued in a most convincing; way that we are in

possessio1l of no direct evidence to indicate that Galileo was acquainted

with Zabarella or his teachings; and, even if he had been, there is noth-

ing to show that he was at all influenced by thetn.8 Even if Galileo did

come into contact with Zabarella's ideas, it seems as though it would

have been after the Tuscan s transferral to Padua ill I592, 'while, to

quote Randall, 'the echoes of the great controversies over method be-

tween Zabarella on the one hand arld Francesco Piccolomini and his

disciple Petrella on the other, fought in the I580'S, were still resound-

ing. 9

In the present paper, however, we wish to compare Zabarella and

Galileo on another issue, where according to the Cassirer-Randall thesis

there should be a close point of contact. According to Randall, Zaba-

rella stands out from his predecessors through his more sophisticated

notion of'scientific experience' wllich points the way to Galileo's 'sci-

entific method':

The originality of Zabarella, and of the whole development of which he is tlle culmi-

nation, is thus to set off a 'scientific experience' from mere ordinary observation, the

accidental or planless collection of particular cases. The weakness of tlle logic of tlle

Scllloolmen llad lain precisely in tlleir acceptance of first principles establislled by mere

colllmon observation. Ill contrast, Zabarella, and with him the wllole new science, in-

sisted that experience mtlst first be analysed carefully to discover the precise 'principle'

or cause of the observed effects, the universal structure involved in them.l°

What, however, seetns to emerge from a study of tlle llotions of 'ex-

perience' atld 'experiment', as used by Zabarella and Galileo, is that tlle

latter, even before he went to Padua in I592 (at the age of 28), had a

8 Art cit. Professor Gilbert, however, is not quite right in asserting that 'there is no

mention of Zabarella in the whole mass of Galileo's writings' (p. 224), for there seems to

be at least one. See Antonio Favaro, 'Capitolo illedito e sconosciuto di Galileo Galilei

contro gli aristotelici', Atti del Reale Istituto Veneto di scien:ze, lettere ed arti, ser. VII, III

(I89I-I892), I-I2, at p. 8, which reads:

'Fioriro un tempo il padovano nido

un Zabarella, un Mainetto, un Speroni'

This poem, not included in the national edition of the Opere was written about I623. I

an indebted to Professor William P. Edwards for calling this to my attention. See n. 7,

p. 66 of Professor Edwards' article cited below in my n. I37.

9Op ct p 6

io Ibid., p. 55. In the view ofthe present writer Zabarella is not so far from the School-

men as Randall claims and is certainly in many ways much closer to the I3th- and I4th-

century Schoolmen than to Galileo regarding questions of method. See Neal W. Gilbert,

Renaisfance Concepts of Metllod (New York, I960), p. I73.




CHARLES B. SCHMITT

8 5

more clearly defined notion of experiment and a more modern-

sounding one, too-than we find in Zabarella's most mature writings,

although the Paduall does display a considerable and perhaps unexpect-

ed knowledge of a rather wide range of sexperiences'. Moreover, the

way in which the young Galileo expresses his distinction between sex-

periment' and 'experience' is quite unusual and does not seem in any

way to reflect traditional Aristotelian usage, although his terminology,

both in the Latin and in the Italian works, betrays significant peripatetic

elements.l1 Although Galileo does make a clear distillctiotl between the

two, as we shall see more fully below, 'experiment' is considered by him

to be of a quite limited application for the investigation of prolJlelus of

natural pllilosophy.

Our analysis of the meaning alld function of sexperience' and sexperi-

ment' in Galileo will, tllen, be larg;ely confined to the De motu, written

before hls arrival at Padua. This will allow us to minimize any direct

influence on him by Zabarellal2 alld the Paduall tradition and to e^ralu-

ate independently the thougllt of the two rne11 on this subject. It will

also provide us uTith a foundation for further more detailed and more

comprehensive studies on the evolution of these lnLotions as Galileo ma-

tured.l3

Before turnillg to an analysis of the writings of these two men, haw-

ever, I would like to say a few words about the notions of'experience'

and 'experiment' as they developed in late medieval and early modern

thought. Our treatment here nTill of necessity be brief, but I hope that it

will indicate, to some extent, the complexity of the problem of inter-

pretlng and categorizillg the various uses to which these ideas were put.

Although a good deal has already been done to explicate the role of

ii For the peripatetic background of Galileo's language in the Italian works see Maria

Luisa Altieri Biagi, Galileo e la tcrminologia tecnico-scacntifica, in Biblioteca dell' Archivillm

Romanicum, ser. II, 32 (I965), 25-4I . The conclusions of this study, which is based on the

Italian works of Galileo, is that, although Galileo did not reject wholesale the significant

scientific terms used before him, he had a strong tendency to refuse to use the Aristotelian

terminology. It must be said, however, that the De motll betrays significantly more Aris-

totelian elements in terminology, as well as in doctrine, than do the mature Italian works.

Galileo's key methodological terms, viz. metodo risollltivo and ncetodo cof?1posifivo are, of

course, traditional Aristotelian usages and are to be found in their Latin form in Zabarella,

as Cassirer and Randall have pointed out.

12 If Galileo was influenced by Zabarella before he arrived in Padua it must have been

through the Opera logica (Ist ed., Venice, I578). The De rebus llaturalibus, which utilizes

many interesting experientiae, as we shall see below, was not printed until I590, by which

time the De motu had probably been completed.

13 For some indications see our conclusions below, pp. IIO-II4.




8 6

TWO TERMS IN ZABARELLA AND GALILEO

'experience' and 'experiment' in late medieval and early modern thought,

we still lack a comprehensive analytic treatment of the meaning and

function of these terms which takes into account the range of uses to

which they were put during the period. I preface this material primarily

to caution the reader about accepting the applicability of a given inter-

pretation of these central concepts, without first taking the greatest care

to determine precisely what they mean as used by a particular author in

a particular context.

Although 'experimental method', as a new intellectual concept, might

be attributed to the seventeenth century with some justification, this

does not mean that it does not have roots which lie in the more distant

past. Already in antiquity, Cexperience' played a central role in Aristot-

le's philosophy, served as a foundation for the so-called Empirical

School of medicine, which produced so influential a writer as Sextus

Empiricus, and was considered to be an important ingredient in the

r

tra1n1ng ot orators.

The importance of'experience'-as well as 'experiment' in some rud-

imentary sense of the word during the Middle Ages has been called to

our attention by the late Professor Lynn Thorndike and others. How-

ever, as Dijksterhuis has so aptly pointed out, not only does there not

seem to be a clear distinction between 'experience' and 'experiment' in

western medieval thought, but the words themselves (i.e. experientia

and experimenttlm), as often as not, have strongly occult overtones.14 In

fact, from the point of view of one interpretation at least, 'experience'

goes hand in hand with the occult or magical tradition, which is to be

sharply distinguished from the rational movement which dominated

nzedieval philosophy, theology, and scientia. Whereas these latter disci-

plines were considered to be determined by a structured and logical or-

der, knowable through reason, magic, which deals with the contingent,

must rely directly upon experience.15 Although such a distinction might

be considered to be typically medieval, it also clearly comes over into

certain sixteenth-century writers. For example, the Renaissance magus,

Henricus Cornelius Agrippa of Nettesheim, still emphasized that truth

is to be found 'longa experientia, plus quam rationis indagine . . .'.16

14 E. J. Dijksterhuis, The Mechanization of the World Picture, trans. C. Dikshoorn (Ox-

ford, I96I), pp. I38-I40.

15 Eugenio Garin, Medioevo e Rinascimento, 2nd ed. (Bari, I96I), pp. I50-I9I, esp. pp.

I58-I59, I88-I90; Charles G. Nauert, Jr., Agrippa and tZle Crisas of Renaissance Thought

(Urbana, I965), pp. 2I4-2I5.

16 Nauert, op. cit., p. 2I5, citing from Agrippa's De occulta phitosophia, I, Ch. IO.




CHARLES B SCHMTT

87

Furthermore, there was a long medieval tradition, coming forward at

least into the sixteenth century,17 which consistently used the word ex-

perimentum to mean a recipe or formula of some sort used to bring about

a non-natural change in the course of natural events. Typical of such a

usage is the following example to be found in Peter of Spain's (Pope

John XXI) popular Summa experimentorum sive thesaurus pauperum: 'The

proper experiment for curing jaundice is a remedy of ivory rubbings

and extract from the liver.'18

17 For a I6th-century example see Ioachim Fortius Ringelbergius, Lucubrationes vel

pOtiles absolutissima KVKXouraC6eLa . . . (Basel, I 54I), p. 7I9.

18 'Ad curandam ictiteiam [ ] proprium experimentum recipe (?) rasure eboris, succi

epatice . . . ,' Summa experimentorurn sive thesaurus patlperum magistri Petri Yspani [Ant-

werp, I497], f. d2r. As an example of the range of materials included during the Middle

Ages under the categories of experimentum and experientia see John Henry Bridges, ed.,

The 'Opus Majus' of Roger Bacon (Oxford, I 897), II, I67-222, pars sexta: De scientia exper-

imentali. This is a very mixed bag, including materials on rainbows, medicine, alchemy,

and explosives, among other things. See also Lynn Thorndike, A History of Magic and

Experimental Sciealce (New York, I923-I958), II, 435-448 (on Albert the Great); II, 854-

8 5 5 (011 Arnold of Villanova); and II, 906 (on Pietro d'Abano), which illustrates the wide

diversity of meaning among the various usages of experientia and experimentum. The dis-

cussions of Arnold of Villanova and Pietro d'Abano clearly indicate that experience is

considered to reveal to us information which cannot be reached through reason. A most

significant example ofthe way experimentumwas sometimes used in theMiddleAges is to

be found in a document of the acts of the Vominican Chapitre provincial de Bordeaux, dated

I5 August I3II [from the Bibliotheque publique de la ville de Toulouse, MS. 490 (I,

273), f. 4I2V]. It reads as follows: 'Item, prior provincialis, de consilio difEmitorum, in

virtute sancte obedientie precipit omnibus fratribus habentibus libros nigromanticos,

experimenta, conj urationes et quecumque scrip ta supersticiosa , quo d infra VIII dies ab

audientia vel notitia hujus precepti, prioribus suis vel eorum loca tenentibus ea tradant,

et ipsi priores vel eorum loca tenentes priori provinciali ea tradant quam cito eis fuerit

oportunum.' As cited in C. Douais, Les freres precheurs en Gascogne au XIIIe et au XIVe

siecle (Paris, I885), p. I2I. My attention was called to this by K. W. Humphreys, The

Boole Provisions of the Mediaeval Frairs, 1215-1400 (Amsterdam, I964), p. 43.

The failure to distinguish the two terms in the medical literature is clearly brought out

in the I 6th-century medical lexicon,Joannes Gorraeus, DefiEnitionum medicarum libri XXIV

literis Graecis distincti . . . (Frankfurt-am-Main, I578), f. 364V, which reads as follows:

7retpa Experimentum sive experientia. Vocabulum est empericorum proprium. Sig-

nificat autem eius frequenter et eodem modo visum est, comprehensionem atque me-

moriam; vel definire potes, experientiam esse eius quod eodem modo visum est, observa-

tionem atque memoriam. Idem vero est observatio atque experientia. Galeni de optima

secta. Est et experientia, quam oL e,u7retptKot KaL ,ueOo6tKoL 7retpaV TpL$LKXV quasi iam tritam

experientiam appellabant, ab experimentali disciplina ductam, experimentalem vero dis-

ciplinam vocabant eorum habitum quae ita frequenter apparuerunt, ut iam inde theorb

matasintcomparata,perceptumque numquid illasemperaut plerumqueaut utrovis modo,

aut raro evenire soleant. Scribit Galenus libello de subfiguratione empirica.' Itisinteresting

to note that the first edition of Gorraeus' (I505-I577) work, printed at Paris by Andre

Wechel in I 564 has no entry under retpa. It was added only in the second edition pub-

lished posthumously.




8 8

TWO TERMS IN ZABARELLA AND GALILEO

On the other hand, 'experience' could also function quite diSerently

for the medievals. There seems clearly to be present in some of the writ-

ings of the Middle Ages, if not an experimentalism in the modern sense,

at least some use of intelligent observation and the consequent applica-

tion of the results of this to specif1c problems of natural philosophy. One

such example albeit, one of the most modern-sounding instances

which we find in the Midcile Ages and one which holds up well even

when compared with seventeenth-century examples is Jean Buridan's

well-known critique of Aristotle's theory of projectile motion. Here

Buridan gives a most telling series of experientie which point up the

many real problems involved in a theory of projectile motion that re-

quires that a medium serve as the moving agent of a projectile in accord

with the Aristotelian doctrine that omne quod movetur ab alio movetur.19

There are several sciences such as astronomy and anatomy to leave

aside the perhaps better-known examples of optics and magnetism-

which functioned as observational, if not experimental, sciences long

before Galileo, Bacon, and the seventeenth century. Astronomy, which

by its very nature cannot be experimental in the normal sense of the

word,20 was observational long before the scientific revolution. By this

I mean that charts, tables, and mathematical calculations were made on

the basis of direct observation of the heavenly bodies. The evidence

which we have for this is the astronomical tables compiled all through

the Middle Ages, as well as the many extant astronomical instruments

For an interesting example in English see OED, m, II, 429C (Experiment), which shows

that in Wyclif's Bible (Genesis, XLII, I5) a I382 redaction has 'experyment', while the

I 3 8 8 version has experience in the same passage. The vulgate has experimentum . The evi-

dence seems to indicate that a llighly developed sense of experiment and a clearer dis-

t inct ion between experience and experiment was current in m edieval Arabic thought .

See the important paper, A. I. Sabra, 'The Astronomical Origin of Ibn al-Haytham's

Con cept of E xperiment , forthcom ing in A ctes du X IIe coslgres international d histoire des

sciences (Paris, I968). I am indebted to Dr. Sabra for allowing m e to see his paper befor e

its publication.

19 This is to be found in Buridan's Questiones super octo phisicorum libros Aristotelis,

Book VIII, question I2. A modern edition of the relevant passage is to be found in An-

neliese Maier, Zwei G rllndprobleme der scllolastischen N aturphilosophie (ROnle, I95I), pp.

207-2I4. For an English translation and a discussion of its significance see Marshall

Clagett, Science of Mechanics in the Middle Ages (Madison, I959), pp. 533-534, 538.

20 By this I mean that it cannot directly utilize 'experiments' in the sense of observa-

t ional situations designed by an experim enter and m aking use of artificial boundary con -

ditions, contr olled variables, etc. The classic distinction between observational and ex-

perim ental sciences is due, of course, to Claude Bernard, Iltroduction a l ettude de la meSde-

cine expeSrimentale (Paris, I 865) .




CHARLE S B . S CHMITT

8 9

which date from before the invention of the telescope. And, indeed,

some of the most acute quasi-experimental observations of the sixteenth

century are to be found in writings on astronomy.21

Anatomy also became predominantly an observational science, at

least from the time of Andreas Vesalius onward. The great anato1nist, in

establishing the practice of public anatomical demonstration, showed

himself to be a keen and diligent observationist, refusing 'to say any-

thing with certainty after only one or two observations'.22 Moreover,

he clearly realized that a science he would have said an art such as

anatomy deals with a subject matter which admits of a good deal of

variation from the normal and that exceptions must be taken into seri-

ous consideration in formulating a descriptive anatotny of the 'nortnal'

human subject.23 Moreover, Vesalius clearly stated that the physician

himself must be involved in the necessary manual procedures and must

not leave the dissections to his assistants.24 All of this means that the ob-

servations must be many and that they should be carried out with con-

sistency and rigor by tlae anatomist himself.

Another element which contributed in a positive way to the empiri-

cism and experimentalism of the seventeenth century the controversy

is over whether this contribution is the crucial one in the evolution of

seventeenth-century 'scientif1c method' or whether it contributed only

in a secondary way is the tradition which comes from technology and

craftsmanship.25 Througkout the sixteenth century there evolved a

21 See especially the examples cited in Francis R. Johnson, Astronomical rllought in Ren-

aissanceEngland (Baltimore, I937) and Richard FosterJones, Ancients and Moderns, 2nd

ed. (Berkeley and Los Angeles, I965), pp. 3-22.

22 '. . . utqui neque alias ex una atque altera sectione quicquam affirmare soleam.' An-

dreas Vesalius, Epistola, rationem modumque propinandi radicis Chyllae decocti . . . (BaselM

I546), p. I39. Cf. Mloritz Roth, Andreas Vesalius Bruxellensis (Berlin, I892), p. I08 and

C. D. O'Malley, Andreas Vesalius of Brussels: 1514-1564 (Berkeley-Los Angeles, I964), p.

II6, who cites an incorrect page number. This aspect of the medical tradition is neatly

expressed in Ioannis Gallego de la Serna . . . Recte ac dogmatice medendi vera mettlodus . . .

(Paris, I639), p. I, which succinctly states: 'eadem scilicet observatio sive experientia

saepius repetita'. This work as a whole has much of interest with regard to problems of

methodology. Here again (e.g. pp. 289-290) the terms experimentum and experientia are

used in an interchangeable way.

23 See William L. StrausJr. and Owsei Temkin, 'Vesalius and the Problem of Variabi-

lity', Bulletil of the History of Medicisle, XIV (I943), 609-633.

24 '. . . tum demum misere collabi coepit [scil. medicina], quum ipsi [i.e., medici]

manum munus ad alios reijcientes, Anatomen perdiderunt.' Andreae Vesalii . . . De humani

corporis fabrica libri septem (Basel, I 543), f. 82v.

25 of the now large literature on this subject the following should be especially noted:

Leollardo Olscllki, Geschicllte der neusprac1l1icllen wissenschaftlichen Literatur (vol. I: Die




90 TWO TERN1S IN ZABARELLAAND GALILEO

more and more highly developed technology which necessarily con-

tributed one important ingredient to seventeenthwentury science with

its increasing utilization of instruments, experimental apparatus, and

laboratory procedures. Telescopes, microscopes, barometers, thermom-

eters, and the various types of demonstration apparatus, all of whicl

played a significant role in seventeenth-century science, are due in one

way or another to those who had been trained in the craft and techno-

logical tradition.

Despite these many positive contributions by the medieval and Ren-

aissance empirical traditions it must still be emphasized that in the six-

teenth century there was yet an urlresolved ambiguity between experi-

entia and experimentum, as used in the philosophical and scientific litera-

ture. It is perhaps nowhere more evident than in Francesco Buonamici's

De motu.26 Buonamici, important as one of Galileo's teachers at Pisa,

seems to make no distinction whatever between the two terms, but uses

them interchangeably. This is quite apparent in the methodological in-

troduction, which is prefaced to the work (where I literally translate

experientia as 'experience' and experimentum as 'experiment'):

Great is the power of experience which arises from the memory of things which sense

time and again supplies; for indeed memory comes from repeated sensation. Many

memories of the same thing grant the means of one experience; moreover, cognition of

Literatur der Technit und der angewandten Wissenschaften vom Mittelalter bis zur Renaissance,

Heidelberg, I9I8; II: Bildung und Wissenschaft im Zeitalter der Renaissance in Italien, Leip-

zig, I922; III: Galilei und seitle Zeit, Halle, I927); Edgar Zilsel, 'The Origin of William

Gilbert's Scientific Method', Journal of tlle History of Ideas, II (I94I), I-32; idem, 'The

Sociological Roots of Science', American Journal of Sociology, XLVII (I942), 544-562; Ru-

pert Hall, 'The Scholar and the Craftsman in the Scientific Revolution', in Marshall

Clagett, ed., Critical Problems in the History of Science (Madison, I962), pp. 3-23; Adriano

Carugo and Ludovico Geymonat, 'I cosi detti "esperimenti mentali" nei discorsi gali-

leiani ed i loro legami con la tecnica', in Actes du symposium international des sciences phys-

iques et nlathetmatiques dans la premiere moitie' du XVIIe siecle (Vinci-Paris, s.d., c. I962), pp.

3 5-47; Lynn White, Jr., 'Pumps and Pendula: Galileo and Technology', in Carlo Golino,

ed., Galileo Reappraised (Berkeley and Los Angeles, I966), pp. 96-IIO.

26 Francisci Bonamici . . . De motu libri X quibus generalia naturalis pllilosophiae principia

SUPlmO studio collecta colltinentur . . . (Florence, I59I). The dedication letter (fs. a2r-a3V) is

dated I587. This work has not been very much studied by modern scholars, but see

Alexandre Koyre, Etudesgalilctennes (Paris, I939), I, II, I8-4I.

Buonamici's work seems to form the basis of Galileo's so-called Juvenitia, which are

apparently his notes taken when he was a student in Buonamici's classroom. On the

similarities between Buonamici's De vIOtU and Galileo'sJuvenilia see Antonio Favaro, 'Di

alcune scritture giovanili di Galileo', Atti e memorie detla R. Accademia di scienze, lettere, ed

artl in Padova XXXVII (I92I), 6-II.




CHARLES B. SCHMITT

9 1

the first principles comes from experzments.... The principles, which are in accord

with each individual one, [i.e. science] are derived from experiment: as for example, the

principles of astronomical science are collected from astronomical experience.27

Nor is such confusion confined to Buonamici or Pisa. One finds the

same lack of precision in terminology continuing throughout the six-

teenth century. Elsewhere, I have investigated the function of experi-

ment (or experience) in sixteenth-century discussions of the problem of

whether a vacuum can actually exist in nature.28 The results indicate

that, during the period in question, in writings dealing with the vacuum

problem, although experientia is ge1zerally preferred to experimentum to

describe an empirical event (e.g. the behavior of a water-clock or of a

bellows), said to offer evidence that a vacuum does or does not exist in

nature, both terms are commonly used without distinction. Moreover,

there does not seem to be one usage favored by scholastics and another

by non-scholastics, but the individual differences between writers ap-

27 'Magna etiam vis est experientiae quae nascitur ex memoria rerum quas sensus semel

atque iterum suppeditat; nanque ex repetita sensione memoria propagatur. Multae eius-

dem rei memoriae potestatem unius experientiae faciunt, ex experimentis vero primo-

rum principiorum cognitio gignitur . . . Principia quae secundum unumquodque sunt,

experimenti esse tradere: ut puta, astrologicae disciplinae principia ex astrologica ex-

perientia colliguntur ....' Ibid., p. 4. This discussion continues for the next dozen or so

lines, with the two terms continually used in the same haphazard way. Buonamici's dis-

cussion here recalls the final chapter of the Posterior Analytics, esp. Iooas-g. His text here

seems to conflate two difEerent traditions of translation of the Aristotelian term sjil7relpla,

i.e., experirrlentum and experientia. The former, wllich occurs in the so-called versio com-

nunis of the work (see G. Lacombe et al., Aristoteles Latinus, pars prior [Rome, I939],

pp. I22-I24), was used, for example, in the commentaries on Posterior Analytics, rI, I9 by

Thomas Aquinas, Opera olnnia . . . (Rome, I882f.), I, 40I; Albertus Magnus, Opera omnia

(Paris, I890-I899), II, 230; and Augustinus Niphus, Posteriorum analyticorum subtilissima

commentaria (Venice, I553), f. 79. Encperientia, which occurs in Argyropulos' translation of

the work, was used, for example, by Jacobus Schegk, De demonstratione libri XV . . .

(Basel, I 564), p. 432; Dominicus Soto, In libros posteriorum Aristotelis sive de demonstratione

. . . (Venice, I574), p. 548; and Iacobus Zabarella, In duos libros Aristotelis posteriores ana-

lyticos cosnf1lentarii (Venice, I582), f. I69V. The two terms are used interchangeably by

Paulus Venetus, In libros posteriorum Aristotelis . . . (Venice, I49I), Sig. mm6. Although

we cannot here be exhaustive in this matter, the indication is that the two terms were not

clearly distinguished, but both were used to render Aristotle's sjil7relpla without consistent

distinction. Also see nn. I8, 22, and 30.

28 A brief survey of the situation is given in my 'Changing Conceptions of Vacuum

(I500-I650)', Actes du XIe congres international d'histoire des sciences (Warsaw, I968), III,

34>433. A more detailed analysis of the experimental question is in my 'Experimental

Evidence for and against a Void: The Sixteenth-Century Arguments', Isis LVIII (I967),

352-366.




92 TWO TERMS IN ZABARELLA AND GALILEO

parently went beyond any doctrinal ai1liation.29 Furthermore, this sort

of confusion was not confined nzerely to discussions of natural philoso-

phy, but was evident in discussions regarding other discipli1les as well.30

II. JACOPO ZABARELLA

Jacopo Zabarella31 seems to have been almczst a unique member of the

so-called School of Padua, for he was born and educated in that city,

a1ld later taught at its university. He took his degree there in Iss3, stud-

yi1zg under Ber1zardillo Tomitano (ISI7-Is76) a1zd Marcantonio Genua

(I49I-IS63) atnong others. He becatne professor of logic in IS63 and he

taught natural philosophy as well, from IS68 until his deatll ill IS89.

29 For a sampling of the usages in the sixteenth-century discussions of vacuum see:

Girolamo Cardallo, De s1lbtilitate, in Opera 0Z1lnia (Lyon, I663), III, 360; C0Zzlz1le1ltarium

Collegii Conimbricensis Societatis Iesu in octo lil)ros pllysicorul1l Aristotelis Stagiritae secunda

pars (Lyon, I602), cols. go, 95;Julius Pacius, Aristotelis . . . naturalis auscultationas libri VIIf

(Frankfort, I596), 604-605; Francesco Patrizi, Nova de ulaiversis philosophia (Venice, I593),

part II, f. 64v; Domingo de Soto, Super octo libros pZ1ysicortll Aristorelis q.saestiones (Sala-

manca, I 582), f. 65v; Franciscus Toletus, Co1tlmentaria . . . in octo labros Aristotelis de physica

aHscultatione (Lyon, I580), p. 452; Bernardino Telesio, De rertlm natura (Modena, I9IO-

I923)g I, 88. It is interesting to note that one ofthe most vehement and learned anti-Aris-

totclians of the sixteenth century, Gianfrancesco Pico della Mirandola, considered Aris-

totle's positive contributions to lie in his attention to detail and his exhaustive experi-

ments, rather than in his theoretical contributions to philosophy (non tam doctrina, quam

encintia cz1ra ac diligentibtls encperiznentis). See Encamen vanitatis, rv, prooelll., in Ioannis

Francisci Pici . . . Opera . . . (Basel, I60I), p. 639 and Charles B. Schmitt, Gianfrancesco

Pico della Mira1ldola (1469 1S33) and IXis Critique of Aristotle (Tlle Hague, I967), pp. 59,

72-73. Pico, of course, here shows his sceptical orientation, according to which direct

observations (experi?>lenta) are valued much more highly than is theorizing.

30 See for example the fifteenth-century treatise of Giovanni d'Arezzo entitled De

medicinae et leguZ11 praestantia in Eugenio Garin, ed., La disputa delle arfi llel Quattrocento

(Florence, I947), pp. 35-IOI, esp. pp. 52, 58 65. We read for exarnple: 'Sed si llis vulgus

mordeas verbis, cum nulla sit evasio, ad experimenta fugam arripiunt. Vidisse enim

ferunt, ut iam plerumque explorare coepi, experientias incredibiles . . .' (p. 52). See also

tlle text cited above in n. I8.

31 On Zabarella see especially Edwards, op. cit. and idem, 'Zabarella', in Enciclopedia

filosofica (Venice-Rome, I958), pp. I8II-I8I3, which cite the other relevant literature up

to about I958. Sillce then, the following have appeared which are also of value: J. J.

Glanville, 'Zabarella alld Poinsot on the Object and Nature of Logic', in Readi1lgs ill Logic,

ed. R. Houde (Dubuque, I958), pp. 204-226; Gilbert, Renaissance Concepts of Method,

pp. I67-I76; W F. Edwards, 'The Averroism of Iacopo Zabarella', Atti del YII con-

grcsso islternazionale difilosofia (published, Florence, I960), IX, 9I-I07; Antonio Corsano,

'Per la storia del pensiero del tardo Rinascimento, x: Lo strumentalismo logico di I. Zaba-

rella', Giornale critico della filosofia italiasla XLI (I962), 507-5I7; Giovanni di Napoli,

L'i11llllortalita dell'anizila nel Rinascifrle1lto (Turin, I963), pp. 376-379; Wilhelm Risse, op.

cit., pp. 278-290; Mario dal Pra, 'Una "oratio" programmatica di G. Zabarella', Rivista

critica di storia della filosofia XXI (I966), 286-290.




CHARLES B. SCHMITT

93

Although his reputation dllring the seventeenth century as a natural

philosopher and a logician seems to have been equally prestigious, llis

fame in later times has rested primarily on his logical writings.

As we might expect, experience, which had already been given a cen-

tral position in Aristotle's philosophy, reappears in a prominent place

in Zabarella's writings. The Paduan logician's most extensive analysis of

the notion of experience occurs, as we might expect, in his commentary

on text I04 of Book II of the Posterior Analytics (IoOa3-9) where Aris-

totle makes his important point that sensatiolls produce memory and

that from many memories comes a single experience. Experience ulti-

mately turns out to be the keystone of Aristotle's whole epistemology,

for it is intimately connected with the psychological process of the for-

mation of universals. In analyzing the Aristotelian text, Zabarella does

not have much to say which goes beyond the ancient and medieval

commentaries. For the most part he merely follows Aristotle and at-

tempts to make the Greek master's meaning a little clearer.32

To learn more of Zabarella's attitude toward experience and how he

used it as a philosophical (or scientific) tool we must look elsewhere in

his writings. In his short treatise, De motu gravium et levium, which treats

a subject much discussed in sixteenth-century writings on natural phi-

losophy, he utilizes experientia to substantiate one of his arguments.

While discussing whether a 'mixed body' (i.e. one composed of a mix-

ture of elements) ^ill move naturally in 'simple motion' (i.e. rectilinear

motion) or whether it svill move in 'mixed motion' (i.e. a compound

motion, made up of both rectilinear and circular motion), Zabarella

argues that a 'mixed body' will move in 'simple motion', followillg the

natural motion of its prevailing element.33 To give additional force to

his arguments, which are largely taken from the writings of Aristotle

and of his commentators, he adds the followillg:

Experience also confirms this opinion, for btlllders use a simple perpcndictllar line,

wllich they deterllline by lead or by a stone tied to tlle end of a cord. Tllese, llowever,

are mixed bodies and tlley are carried to tlle center of tlle earth by tlle gravity of tlle

prevailing element tllrough a perpendicular line, v17icll is simple, for every straigllt line

32 Iacobus Zabarella, Opera logica (Frankfurt, I623), cols. I267-I273, esp. I269-I270.

For a recent and detailed study of the question in Aristotle see Louis Bourgey, Observation

et experience chez Aristote (Paris: Vrin, I955).

33 Book II, chapters 8-I0. I use the following edition: Iacobus Zabarella, De rebus natu-

ralibus libri XXX (Frankfurt, I6I7), cols. 36I-374. TIlis deals with tne question: An motus

misti factus secundum prevalens elementum sit simplex, an mistus ....




94

TWO TERNS IN ZABARELLAAND GALILEO

extended to tlle center is simple. Moreover, tlle walls of the buildings, unless tlley have

been constructed perpendicularly, cannot last very long, but eventually they fall and

are carried downward through a perpendicular line. Generally, experience teaches us

that mixed heavy bodies, no less than elements, descend in a simple line.34

In order to resolve the question of what type of motion a Cmixed body'

will follow, Zabarella here utilizes the testimony of his own experiellce,

in this case empirically derived principles of statics such as were used by

architects a1ld builders. This certainly is the stuffby which vague theor-

izing, divorced from observation, is overthrown. It shows a sense of

keen observation, a realization that sometimes, at least, one observation

can resolve centuries of rnetaphysical dispute. It also shows Zabarella

had at least some awareness of the practical techniques used by the arti-

sans of his time, something which most interpreters of Renaissance tech-

nology and craftsmanship have denied to university professors who

were supposedly trapped in an ivory tower where no demeaning, prac-

tical considerations were allowed to enter.35 As we shall see, however,

344Experientia quoque hanc sententiam confirmat, nam aedificatores utuntur linea

perpendiculari simplici, quam inveniunt per plumbum vel lapidem capiti funis alligatum.

Haec enim sunt mista corpora et ad centrum feruntur gravitate elementi praevalentis per

lineam perpelldicularem, quae simplex est, omnis enim recta linea ad centrum protenta

simplex est. Parietes quoque acdificiorum, nisi ad perpendicularem [text: perpendicu-

larum] sint fabricati [text: fabricari], durare diu nequeullt, sed aliquando cadunt et per

lineaza perpendicularem deorsum fcrulltur; et omnino docet experientia, non minus

mista gravia, quam elementa, per simplicem lineam descendere.} Ibid., rt, 9, cols. 370-37I.

The bulk of Zabarella's polemic at tllis point is against Agostino Nifo. See Nifo's In

Aristotelis lit:vros de coelo et mulido comenelltaria (Venice, I567), pp. I2-I3, Book I, texts 8-9.

The origin of the problem goes back to Aristotle7s De coelo, Is texts 7-8 (2s8b27f). The

handling of the question by earlier commentators also, in some cases, shows some reliance

on experience. We do not mean to imply here that Zabarella was necessarily more em-

pirical in discussing it than were his I4th-century predecessors. See, for example, Nicole

Oresme, Le Itvre dH ciel et dH molide, text and commentary by A. D. Menut and A. J.

Demony, in Mediaeval Studies III (I94I), I96-I98 [a new edition of this text is in prepara-

tion by Prof. MenutS and the Latin version, as yet still irl manuscript, of Oreslne's Qalaes-

tiones saper lit:vros de caelo et nlundo is being prepared for publication by I)r. Claudia Kren

cf the University of Missouri]; and Joannes Buridan, Quaestiones super lit:vris quattuor de

caclo et nsllttdo, ed. E. A. Moody (Cambridge, Mass., I942), pp. 3I-35. Zabarclla cer-

tainly was aware of earlier discussions of the question, not only those of Medieval Latin

authors, but those of Simplicius Averroes, and others as well. For the general question of

'mixed bodies and their motion see the literature cited below in n. 58* The particular

point at issue here, however whether 'mixed bodies follow the nlotion of their pre-

dominant element does not seem to have been much discussed by the modern scholars.

35 Although a good deal has been written concerning the influence of technology and

craftsmallship on the emergence of 'modern science' and 'scientific method' during the

I6th and I7th centuries, little attempt has been made to relate tllis tradition to the con-

tinuing tradition of natural philosophy in the universities (e.g., see Zilsel, 'The Sociologi-




CHARLES B. SCHNIITT

9 5

Zabarella was acquainted with a variety of manual and practical trades.

Other references to experience occur in the treatise De ordine intel-

ligendi,36 where he several times calls upon experience, in order to sub-

stantiate a point he is trying to make. In arguing that it is easier to know

the individual characteristics which make two objects similar than to

know the characteristics which distinguish them, he contends:

And we also experience this every day, for I llave sometimes seen a certain fish wilicll I

tllouQ,htwas thegoldfisll,but fishermensaid that it was not a goldfish,but a certain otller

species. I had therefore paid attention only to the similarity of this fish to the goldfisil;

I had not, however, paid attention to the difEerence. Thus boys recognize the donkey's

similarity to tile horse and tlle mule, btlt tlley do not discern tlle difEerences between

them. We adults also recognize from a very distant place tlle similarity of tlle llorse,

donkey and mule; tile difEerence, on the other lland, we can perceive only wilen we

have come closer. More easily, tllerefore, tlle similarity is recognized tllan tlle diffel̂ -

ence.37

A similar example is given a few pages further on, whe1z he argues that

a boy recognizes that a horse is an animal before he recognizes that it is

specifically a horse:

cal Roots . . .', p. 550). The examples we have cited from Zabarella are by no means

unique. This is a question which should be investigated further. Without a doubt Leo-

nardo, William Gilbert, and Galileo were influenced by technology, but to a significantly

greater degree than those stodgy conservatives who held university chairs? See above,

n. 25, for a listing of some of the relevant literature on the technological and craft tradi-

tions during the Renaissance. In emphasizirlg the empirical approach of Zabarella I do not

in any way mean to imply that a strongly empirical approach was not also to be found in

certain earlier commentators on Aristotle. A significant appeal to experience is also to be

found particularly among the I4th-century natural philosophers upon whom historians

of medieval science have placed so much emphasis. It is quite evident, however, that early

I4th-century scholastic authors were not the only ones before Galileo to have something

significant to say about experience and its function in 'science'. I)espite the enormous

contributions made to our understanding of the subject by the historians of medieval

science, they often appear to have an inherent prejudice against I6th-century thinkers. It

sometimes seems as tllough for them the early I4th century is a 'golden age' and nothing

else of significance happened until the I7th century. It will only be after a careful study of

the Isth- and I6th-century writers on natural philosophy as well as the I4th-century

ones that we shall be in a position to evaluate what progress was actually made in the

later period.

36 De rebus natllralibus . . ., cols. I04I-I076

37 'Idque etiam quotidie experimur, nam ego aliquando vidi piscem quendam quem

putavi esse auratum piscem, tamen piscatores dixerunt non esse piscem auratum, sed

aliam quandam speciem. Ego igitur solam convenientiam illius piscis cum aurato animad-

verti, diflRerentiam autem non animadverti. Sic pueri convenientiam asini cum equo e

mulo cognoscunt, sed eorum diflRerentias non discernunt. Nos quoque adulti cognoscimus

ex loco valde remoto convenientiam equi et asini et muli, diflSerelltiam vero conspicere

non possumus, nisi propinquiores simus. Facilius igitur convenientia cognoscitur quam

diflRerentia.' Ibid., De ordine intelligendi, ch. I2, col. I065.





However, this is clcarly verified by experience, for boys at first do not distingtush a

llorse from a donkey nor from an ox, but they call all of these by the same name,

'oxen', since tlley observe that roup;ll outline and motion of an anilllal and they see the

common accident tllat all of these draw a cart; but tlley do not yet discern tlle particu-

lar delineations of tlle figure of tlle individuals and tlae particular conditions of tlleir

motions, for the former diSerences contain the latter ones; and, tllerefore, tlley require

a ^,reater power of judgment 3n the sense or;an to be seen.38

These passages certainly seem to echo the f1nal sentence of the first

chapter of Book I of Aristotle's Physics, where he had argued that chil-

dren at first call all men 'father' and all women 'mother', but later learn

to distinguish more carefully.39 Again we see an awareness on the part

of Zabarella that observation and experience have an important func-

tion to play in philosophy. He here seems to distinguish several levels of

experience, based upon increasing sophistication and knowledge of the

subject tnatter. A boy's powers of observation and judgment, as yet in-

choate, are not sensitive enough to distinguish one type of animal from

another, for, though he is able to recognize the similarities, he cannot

yet grasp the difference, which requires more highly developed powers.

Or, at a distance one can easily recognize a four-footed animal, but can-

not distinguish always a donkey from a horse until he is able to see the

animsals in question a little closer. On the other hand, the expert, or one

whose powers of judgment have been developed to a high degree in a

particular area of enquiry, is to be especially heeded, for his greater ex-

perience and knowledge of the subject matter make hirn able to com-

prehend fine distinctions and to recognize subtleties which the untrained

observer is unable to recognize. Thus, a f1sherman is better able to dis-

tinguish one particular species of fish from another species than is the

layman who has no detailed knowledge of f1shes or experience in deal-

ing with them.

Something which might be noted about the above examples of Za-

barella's use of experience ill his philosophy is that they may not be based

upon his own personal experie11ce at all, but he may nzerely be repeating

38 'Hoc autem experientia manifeste comprobatur, nam pueri primum non distin-

guunt equum ab asino neque a bove, sed eos omnes eodem nomine boves vocant, quia

rudem illam animalis figuram et motum conspicantur videntque illud commune accidens,

quod hi omnes currum trahunt; at particularia lineamenta figurae sillgulorum et particu-

lares motuum conditiones nondum discernunt, hae llamque differentiae continellt illas,

quare maiorem iudicandi vim in sensu requirunt, ut videantur.' Ibid., col. I067.

39 I 84bI2-I4.




CHARLES B. SCHMITT

9 7

the stories which he had read or heard.40 Even if this is true, however,

the ultimate experiences upon which the conclusions are based exhibit a

sophisticated and highly developed view of reality. We have, however,

an additional passage in which Zabarella speaks of experience and this, I

think, is decisive in indicating that his own personal experience is in-

volved in at least some of the instances cited. The passage of which I

speak appears in his De regionibus aeris4l and seems to indicate clearly

(I) that Zabarella himselfwas observant of nature and (2) that he ap-

plied what he learned from experience and observation to his philoso-

40 For other examples of his use of experience to resolve philosophical disputes see the

following passages in the De rebus naturalib?ls: col. 69 (De naturalis scientiae constitutione,

ch. 24), col. I056 (De ordine intellige1ldi, ch. 8), and col. I069 (De ordine intelligendi, ch.

I3). I cannot quite agree with Edwards' low estimate (Tlle Logic of Iacopo Zabarella, p.

286) of the use which Zabarella made of experience. Although it is true that Zabarella

refers to nothing more than 'boiling tea-kettles and other very simple machines', the fact

that he refers to these is not as unimportant as it might seem. Even Galileo and the early

I7th-century scientists seldom used intricate or complicated machinery in their experi-

ments. For Galileo and the inclined plane see T. B. Settle, 'An Experiment in the History

of Science. With a Simple but Ingenious Device Galileo Could Obtain Relatively Precise

Time Measurements', Science, CXXXIII (I96I), I9-23.

One of Zabarella's most striking uses of experientia in the context of natural philosophy

is to be found in De 110tugraviu1n et levium I, I5 (ed. cit., cols. 333-338, a chapter entitled:

Cur motus gravium et levium sit velocior in fine, quam in prillcipio, plures aliorum sen-

tentiae). In a further significant passage, where Zabarella argues against Galen concerning

the substance of the eye, he refers to what he has learned from observing an anatomical

dissection. In De visu II, 5 (col. 903) he says: 'Ego igitur oculorum sectione vidi crystal-

linum ab aliis humoribus separatum . . .', a passage pointed out to me by William F. Ed-

wards. This is by no means a unique example of the use of information learned from ana-

tomical dissections in arguments concerning natural philosophy and sensory psychology

during the I6th and early I7th centuries. I plan to treat this topic in greater detail else-

where. For one example see Charles B. Schmitt, 'Giulio Castellani (I528-I586): A Six-

teenth-Century Opponent of Scepticism', Journal of tlle History of Philosophy v (I967),

I5-39, at 33-34. A further aspect of Zabarella is illuminated by Baptistae Fierae Mantuani

. . . Coena notis illustrata a Carlo Avatltio . . . (Padua, I649), pp. 78-79. Carlo Avanzi, in his

notes to the section of the work dealing with alectoriae (Cf. Pliny the Elder, Nat. hist.,

XXXVII, I44), says the following: 'Ostendit etiam mihi V. C1. Jacobus Zabarella, Patavii

olim Simplicium Professor, lapillos aliquot varii coloris et figurae: quos in annosi capi

ventre repertos asserebat. Qui porro an fuerint in illius ventre geniti, an ab eodem cum

cibo deglutiti, in re incerta non afl5lrmaverim.'

The 'experimental' side of early modern Aristotelianism is well expressed by Bartholo-

maeus Keckermann's statement, 'Nolo de hoc plura, nec debeo, quia experientia et sensus

(optimum philosophandi principium) pro me disputat. Fac ergo experimentum, optime

lector, et favebis.' Operum omnium quae extant tomus primus (Geneva, I6I4), col. I80I .

This is from the treatise Contemplatio gemina: prior ex generali physica de loco, altera ex

speciali de terrae motu (I60I).

41 De rebus naturalibus, cols. 54I-556.




98 TW0 TERMS IN ZABARELLAAND GALILE0

phy, especially to his works on natural philosophy.42 In this particular

work, Zabarella discusses the regions or layers of air, which Aristotle

made the basis of his meteorological system, what their relation is to

one another, and how they interact. In the course of his discussion Za-

barella takes up the matter ofthe different properties of the two gaseous

layers above the earth (the layer immediately above the earth being pre-

dominantly air, while the upper layer is a kind of fiery exhalation) and

he focuses upon the specific question of what the different regions with-

in the layer of the air are.43 He argues that there are basically three dis-

tinguishable layers of air. The middle one is slightly cooler than either

the upper or the lower layer and is also generally more humid. In order

to help substantiate his position, Zabarella again turns to experience;

and, in this case, the experience seems certainly to be one which the

Paduan has personally undergone:

We can also verify what we have said by experience. There llappened to me what I

have also heard has llappened to many others, so tllat when I climbed to the summit of

Monte Venda,44 whicll is the highest of all those in the Paduan plain, I tllere found the

air to be very calm throughout tlle day; but below, around the middle of tlle moun-

tain, I saw clouds, which obstructed my vision of tlle valleys. Afterwards, in tlle eve-

ning, I descended from the mountain, however, and I discovered that, that day, tllere

had been a great rain on the lower part, while on the peak ofthe mountain it had not

rained at all. From this I understood that I had passed through the middle region of the

air in whicll the rain had been formed, and yet I did not feel that region below as very

cold, but I scarcely noticed any diSerence of cooler and warmer air, for it was summer-

time and I llad dressed for summertime, and yct I did not feel cold enough there to be

42 It will be noted that the majority of the examples we cite are from the collection of

opuscula on natural philosophy, entitled De rebus naturalibus libri XXX. This collection,

which has hitherto been little studied, contains most of Zabarella's writings on the

naturalistic works of Aristotle. He did write a commentary on the De anima, it is true,

but his commentary on the Physics is fragmentary, covering only Books I, II, and VIII. The

latter was published only posthumously (Venice, I60I). Although Zabarella's influence

as a logician has been recognized (see the works of Edwards and Petersen cited in n. 2, as

well as Gilbert, Renaissance Concepts of Method, pp. 2II, 2I3-2I8), the extent of his in-

fluence on the I7th-century German university teaching of natural philosophy has hardly

been noticed. The theses of the period disclose that he was considered to be a major

authority in natural philosophy. See, for example, Rodolph Goclenius, Adversaria ad

exotericas aliquotJulii Caesaris Scaligeri . . . exercitationes, 3rd ed. (Marburg, I606); Bar-

tholomaeus Keckermann, Systema pllysicum (Hanover, I6I2); and Thomas Sagittarius,

Physicorum Aristotelico-Scaligereorum pars prior (posterior) (Leipzig, I654).

43 Zabarella takes as his starting point Book I of Aristotle's Meteorology, esp. ch. 4. The

key text in which the diflSerentiation between the two regions or layers is made is at

34IbI I-24.

44 Monte Venda, which is 603 meters high, is about IS kilometers southwest of Padua.

The highest of the Colli Euganei, it has a commanding view of the surrounding area. At

the present time it is the site of a meteorological observation station.





9 9

uncomfortable. That region, tllerefore, is not absolutely cold but only so in comparison

to the warmer air below.45

Although Zabarella's conclusions may not be in close agreement with

more modern meteorological theories, they, nevertheless, do indicate

that he is making an attempt to found his science upon observation. This

text clearly indicates that Zabarella did take it upon himself to go out

and look at nature; and, what is rnore irnportant, he observed carefully

what he saw and applied it to the crucial philosophical questions in

which he was interested.46 Here is an observant man, a philosopher who

appears to be worthy of the high estimate which Randall has given him.

After he has related to us the account of his trip to Monte Venda,

Zabarella turns to still another example from his own experience to

substantiate the view that tlle condensation of water vapor can occur

not only when the vapor comes into contact with sornething cold, but

also, when in contact with sornething warm, provided the warm object

is cold relative to the vapor. He turns again to an experience derived

from the world of technology:

The distillation of water offers an important testimony to the trutll, for we see from

the droplets in tlle st ll that the vapor is raised by tlle fire below, is condensed on tlle

still's openin;, and is chan;ed into water; nevertheless, if we touch the opening with

our hand, it is exceedingly llot and sometimes so hot tllat we cannot stand touching

our hand to tlle heat. But, how can it llappen that when it is llot it cllanges steam to

water, if this can happen only by cooling? Therefore, it must be said tllat tlle openin;

can be hot, although it functions as cold with respect to tlle hotter steam rising from

the fire below. Water, therefore, can come from the hot substance tllrou;h condensa-

45 'Possumus autem etiam per experientiam id quod diximus comprobare. Mihi ellirm

contigit id quod etiam aliis pluribus contigisse audivi, ut ascenderem ad summitatem

usque Montis Veneris, qui omnium in Patavino agro altissimus est, ibi per totum diem

habui aerem serenissimum, sed infra circiter medium montis videbam nubes, quae me

visione vallium probibebant. Vesperi autem postquam de illo monte descendi, inveni

factam eo die in infera parte magnam pluviam, quum in montis cacumine nihil pluisset.

Ex eo intellexi me transisse per mediam aeris regionem in qua est facta pluvia, nec tamen

eam sensi frigidissimarm, imo ut vix aliquam animadverti differentiam frigidioris et cali-

dioris aeris, nam aestivum tempus erat et pro aestivo tempore eram vertitus, nec tamen

tantum frigoris quod me laederet ex eo loco percepi. Pars igitur illa non est absolute

frigida, sed solum comparatione inferi aeris calidioris.' De regionibus aeris, ch. 8; De rebles

naturalibus, col. 554. The title of this chapter is: 'Dictae sententiae confirmatio per om-

nium difilcultatum solutionem et per experientiam.' Zabarella's 'experience' on his trip to

Monte Venda seems to have made an impression on later meteorological writers. It was

directly quoted and discussed, for example, by Adriaan Heereboord, PZailosopllia naturalis

(Nigmegen, I665), II, 358-359 and Robert Boyle, Tlle Worlis of tle Honourable Robert

Boyle (London, I772), V, 695 (in the treatise General History of tlle Aar).

46 For another excellent example of careful observation and its application to a philo-

sophical problem by an Italian Aristotelian see my paper cited in n. 40.





tion, for when it acts as less hot, it acts as cold. For this reason it is not necessary tllat the

air of tlle middle region be exceptionally cold, to cllange vapor into water, but it is

sufilcient if it is less hot tllan the lower air and less llot tllan the vapor, which having

been raised up tllrough the lower air, is borne to the middle rep;ion.47

Again we see that Zabarella was acquainted with the technology of his

time and, what is more, applied the knowledge which he derived from

it to his investigations in natural philosophy. One might here contrast

Zabarella, as a part of an observationalist scholastic tradition, to one

such as Thomas Aquinas and his followers in theologico-metaphysical

scholasticism who seldom concerned tllemselves with such matters. Za-

barella's philosophy was not entirely confined to the classroom and li-

brary, but he had contact with the everyday world of the artisan. He

was acquainted with the work of builders, fishermen, and alchemists;48

moreover, he, himself, was interested enough in natura to climb to the

top of the highest mountain in the area. While there he was observant

enough to attempt later to correlate the results of his observations with

the accepted meteorological theory.49

The limitations of Zabarella's use of experience and what perhaps

marks a distinguishing factor between the methodology of the sixteenth-

cel1tury Italian Aristotelians and that of Galileo and his followers in the

next century lies in his reluctance to abandon certain deeply ingrained

Aristotelian notions, even in the face of contrary evidence. Although

many Aristotelian teachings on natural philosophy just did not seem to

agree with everyday experience, every attempt was made to retain as

47'Magnum quoque veritatis testimonium praebent stillationes aquarum; videmus

enim e roribus [text: rosis]in stillicidio existentibus, supposito igne vaporem elevari et in

operculum stillicidii incidentem condensari et in aquam mutari; attamen si operculum

illud manu tangamus, valde calidum est et quandoque ita calidum, ut manu tangentes

tolerare calorem illum nequeamus. Qui enim fieri potest, ut quum sit calidum mutet

vaporem in aquam, si facere id non potest, nisi refrigerando? Dicendum igitur est oper-

culum illud, licet calidum, frigidi tamen operam praestare respectu vaporis ascendentis

calidioris ob suppositum ignem. A re igitur calida potest per condensationem aqua gene-

rari, quia, dum agit ut minus calida, agit ut frigida. Quare non est necessarium ut aer

mediae regionis, si debeat vaporem in aquam mutare, sit frigidissimus, sed satis est si sit

minus calidus quam inferus aer et quam vapor, qui, per inferum aerem elatus, ad mediam

regionem perducitur.' De regionibus aeris, ch. 8; De rebus natljralibus, col. 554.

48Seen 35above

49 Another interesting example which indicates that Zabarella had experience outsidc

of the lecture room is to be found in his commentary on the Posterior Analytics, where in

the Latin text of the discussion he introduces a vernacular phrase to help clarify the mean-

ing of a passage of Aristotle's Greek which is not clear in the Latin translation. See text

I04 of Book II, Opera Logica, col. I27I.





10 1

much as possible from the peripatetic system and if a certain concept

could feasibly be retained by making minor adjustments elsewhere in

the system this was usually done. Major discrepancies in the laws of mo-

tion had been noticed several times previously e.g. by Philoponus and

Simplicius in antiquity, by Buridan and Oresme in tlle fourteenth cen-

tury, and by Benedetti and Tartaglia in the sixteenth but the frame-

work of the Aristotelian system was still generally accepted at Zabarel-

la's time.

One very basic Aristotelian notion which Zabarella desired to retain

was that of thefuga vacui. Aristotle's rejection of even the theoretical

possibility of a void existing in llature and the subsequent discussions

arising from this has a long and significant history which I cannot go

into here.50 Since the ultinzate death blow to Aristotle's theory was

dealt by the experirnents of Torricelli, von Guericke, and their follow-

ers in the decade of the I640S and later, it might be useful to raise the

question: what was the attitude of one like Zabarella, whose emphasis

on experience we have just noted, toward the question of the vacuum

and the possibility of resolving the question through experience? We

might say first of all that, since Zabarella's commentary on Book IV of

the Physics does not seem to be extant we do not have his detailed analy-

sis of the vacuum question as a whole. Consequently, we shall have to

be satisfied with the very meager remarks on tlle subject which he makes

in the writings available to us.

Basically, for Zabarella as for Aristotle, science can deal only with

those things wllicll are; consequently, it does not concern itself with

those thirlgs which are not. Therefore, strictly privative or negative no-

tions such as 'vacuum' or 'inftnite' have no place in a true science.51 This

explanation seems to be adequate for the Paduan, if we can judge from

what he says in the w-ritings which have come down to us. In his treatise

De Naturalis scientiae constitutione, where he discussed a nurnber of ques-

50 See especially Werner Gent, Die Pltilosophie des Raumes und der Zeit, second un-

revised edition (Hildesheim Ig62); Pierre Duhem, Systeme du nlonde (Paris, I9I3-I958),

esp. vols. I and VIII; Cornelis de Waard, L'experience barometrique: ses antetcedents et ses ex-

plications (Thouars, I936); and Max Jammer, Concepts of Space, 2nd ed. (New York,

I 960) .

51 'Ad hoc responderi solet distinguendo cognitionem: haec enim duplex est, unam

vocant positivam, alteram privativam .... Privativa autem noll entis CogllitiO est

cognoscere ipsum non esse et falsam propositionem falsam esse, quam cognitionem dari

non negaret Aristoteles: propterea in libris Physicorum docuit infinitum et vacuum non

dari.' In libros posteriorum analyticorunz commentaria, Book I, text IO; Opera logica col. 658.





tions of natural philosophy, he passes over 'vacuurn' with a bare men-

tion.52 The most interesting passages regarding vacuum, and one which

clearly shows Zabarella s opinion on the subject, occurs in his De motu

gravium et levium. In chapter IO of Book I ofthis work,53 Zabarella con-

siders the famous text 7I of Book IV of the Physics, which was of such

great importance in the history of ancient, medieval, and early modern

physics.54 In this text Aristotle discusses the possibility of whether a

body might move through a vacuum with a ftnite velocity. His conclu-

sion is that in a vacuum all solid objects would move at an infinite velo-

city, and from this, and other arguments, he concludes that a vacuum

could not be possible. This particular text was a fertile ground for de-

bate from antiquity until the seventeenth century, and in the numerous

discussions regarding it through the years were set forth many ideas,

both novel and fruitful in the development of quantitative physics.

In his discussion of this text Zabarella generally follows the line of

comrnentators who agreed with Aristotle and his most important de-

fender, Averroes, rather than with those such as Philoponus and Avem-

pace who had rejected the Stagirite's arguments.55 In the course of his

consideration of the question, Zabarella has occasion to argue against

certain recent, but unnamed, authors who were opposed to the Aristo-

te lan posltlon:

52 'Cum tractatione autem de loco coniuncta esse debuit tractatio de vacuo, siquidem

nil aliud significat nomen vacui quam locum sine corpore.' Chapter I2; De rebus naturali-

bus, col. 34.

53 De rebus naturalibus, cols. 3I8-32.

54 See especially Ernest A. Moody, 'Galileo and Avempace: The Dynamics of the

Leaning Tower Experiment',Journal of the History of Ideas, xrI (I95I), I63-I93, 375-422.

To this should now be added Edward Grant, 'Aristotle, Philoponus, Avempace, and

Galileo's Pisan Dynamics', Centaurus XI (I966), 79-95, a paper which appeared too late to

be fully utilized in the present study. For an important recent attempt to integrate the

whole period see Cesare Vasoli, 'La cultura dei secoli XIV-XVI', in Atti del primo con-

vegno internazionale di ricognizione delle fonti per la storia della scienza italiana: i secoli XIV-

XVI (Florence, I967), 3 I-IO5.

55 'Averroes igitur ibi ex Aristotele sumit, necessarium esse plenum ad motum elementi

propterea quod continuitas in motu a resistentia provenit, at in elemento nulla mobilis ad

motorem interna resistentia est, ideo externa requiritur, si debeat fieri continuus motus;

medium enim plenum resistit aliquantum elemento moto et ita facit continuitatem;

quamobrem si daretur vacuum, elementum in eo positum non moveretur, sed momento

temporis ad locum suum transiret, qui non esset motus, sed mutatio subita. Qua in re

Averroes Avempacem reprehendit dicentem ad motum elementi non esse necessarium

medium plenum, quandoquidem etiam in vacuo, si daretur, fieri elementi motus posset

isque continuus ob internam resistentiam.' De motu gravium et levium, Book I, ch. IO; De

rebus naturalibus, cols. 3 I8-3 I9.




CHARLES B. SCHMITT

103

These recentiores rise up against Aristotle and Averroes, and they openly declare that

Aristotle did not understand what resistance there is in the motion of the elements and,

consequently, said many false thin;s regarding tlleir proportions in motion in Book VII

of the Physics. Against these tliings they bring forth many experiments by which they

aver that, what he understood of these proportions is false, and that tllis falsity pro-

ceeds from tlne false foundation tllat the form of the element that moves it does not

possess any internal resistance from tllat wllich is movable, but only external resistance

from a full medium. Therefore, following Avempace's opinion which was rejected by

Averroes, and which was also followed by Scotus in question 9, distinction 2 of the

Second Book of tlle Sezltences, they say tilat the resistance in the natural motion of an

element is twofold: one resistance external and accidental, which comes from a full

medium and makes motion slower in a plenum than in a vacuum; the other, llowever,

internal and essential, by which the moved element resists tlle moving form and tllus,

also in a vacuum (if it be granted), tllere can be continuous motion .... I could cer-

tainly demollstrate easily in defense of Aristotle just how much they have been deceived

in tllose experiments, which they have brought forth against Aristotle, for they cer-

tainly do not refute what Aristotle says about proportions in motion in Book VII of the

Physics; but since this is not related to our present discussion, it must be omitted ....

But if it migllt ever be granted to us to bring out our commentary on the books of

Physics, we shall speak carefully of this matter.56

Here Zabarella very clearly rejects the experiments ofthose who oppose

Aristotle. Unfortunately, he tells us nothing either of the nature of the

experiments, or by whom they have been carried out, or even precisely

why he finds them unsatisfactory. These are all questions to which an

answer would be very desirable. It is most difficult to know from what

he says just what the alleged experiments were meant to show. In cer-

tain ways it seems as though Zabarella's attack is directed toward some

56 'Adversus Aristotelem et Averroem hi recentiores insurgunt et aperte profitentur

Aristotelem non cognovisse quae sit resistentia in motibus elementorum, imo et multa

falsa dixisse in 7 Physicorum de [text: pe] proportionibus in motu. Adversus quae ipsi

plura adducunt experimenta, quibus se cognovisse testantur falsas esse illas proportiones

et hanc falsitatem processisse ex hoc falso fundamento, quod forma elementi movens

ipsum non habet a mobili aliquam internam resistentiam, sed solum externam e medio

pleno. Ipsi igitur, sequentes opinionem Avempaces ibi ab Averroe reprobatam, quam

etiam sequutus est Scotus 2 sententiarum, distinctione 2, quaestione 9, dicunt duplicem

esse resistentiam in motu elementi naturali: unam externam et accidentalem, quae fit a

medio pleno et facit ut tardior sit motus in pleno quam esset in vacuo; alteram vero in-

ternam et essentialem, qua elementum motum resistit formae moventi, ita ut etiam in

vacuo, si daretur, fieret continuus motus .... Ego vero pro Aristotelis defensione possem

facile demonstrare quantum isti decepti sint in illis experimentis, quae adversus Aristo-

telem adduxerunt, revera enim non ofilciunt dictis Aristotelis in 7 Physicorum de pro-

portionibus in motu; sed quoniam alienum hoc esset a nostro instituto omittendum in

praesentia est . . . sed si quando datum nobis fuerit in libros Physicos edere commentarios,

diligenter hac de re loquemur.' Ibid., col. 3 I9. The text of Book VII of the Physics is to be

found at 24gb27-2soa28.





of his contemporaries who actively discussed experiments, which were

apparently meant to demonstrate the existence of a void in nature, and

who may even have themselves carried out such experiments.57 On the

other hand, it seems more probable that the experimenta to which Zaba-

rella is here referring are the hypothetical situations postulated by the

medievals to explain the possibility of the movernent of an object at a

finite velocity in a void space.58 At any rate, the important point here

with regard to our present discussion is that in certain illstances experi-

menta are to be rejected when they give results in opposition to our

world-picture as a whole.59

57 For an analysis of the experimental arguments in favor of a void see my paper cited

in n. 28 and the works of DeWaard and Duhem cited in n. 50. Tlle most likely candidate

for Zabarella's attack, if illdeed the attack is directed against a contemporary, is Bernar-

dino Telesio. Telesio had a reputation already in Zabarella's time for being an 'experi-

mentalist' and we know that his discussion of the vacuum question was framed predomi-

nantly in experimental terms. See Telesio, op. cit., I, 86-go; Cassirer, Op. cif., I, 258-260;

and DeWaard, op. cit., 27-28 for his views on the vacuum question. For his experimental-

ism in general see Antonio Persio, Liber novarum positionum (Venice, I 575), f. 3V; Francis

Bacon, De prilcipiis atque originibus secundum fabulas Cupidinis et coeli: sive Parlenidis et

Telesii et praecipue Democriti philosopZlia tractata infabula de Cupidine, in Tlle Works of Fran-

cis Bacon, ed. Spedding and Ellis (London, I857-I874), m, I I5; Tommaso Cornelio,

Progymnasnlata physica (Venice, I663), II8-I20; R. Caverni, op. cit., I, 435-436.

It must be noted that Telesio was born in ISO9 and was therefore twenty-four years

Zabarella's senior, taking his degree at Padua in I 53 5, when Zabarella was two years old.

It is therefore difficult to see how Randall can maintain in the most recent and most per-

manent form of his 'School of Padua' article that '. . . Zabarella went far along thc path

his pupil [ ] Telesio was to follow'. Career of Pllilosophy, I (New York, Ig62), 298. In the

oricgillal version of his article (Ig40), Randall said, 'Indeed, in his criticism of Platonic

notions of teleology Zabarella went far along the path the radical graduate of Padua,

Telesio was following' (203). In the I96I version, it is held that, '. . . Zabarella went far

along the path the earlier pupil of the Paduans, Telesio, had already taken' (62). This

passage is omitted from still another [abbreviated] version of the article contained in

P. P. Wiener and A. Noland (eds.), Roots of Scientfic Thought (New York, I957), I39-

I46. The present writer also finds it somewhat eccentric to mention only Telesio's rela-

tion to Padua and his criticism of Platonism. First and foremost he was a critic of Aristotle,

as even the most casual reading of De natura rertlm discloses. Garin's judgment (cited in

n. II3 below) seems more valid and more in accord with the actual evidence.

58 A discussion of this subject with Edward Grant of Indiana University and a more

careful consideration of the whole context of Zabarclla's treatmellt makes it appear that

this is the more likely solution. See Edward Grant, 'Motion in the Void and the Principle

of Inertia in the Middle Ages', Isis LV (I964), 265-292; Idezn, 'Bradwardine and Galileo:

Equality of Velocities in the Void', Arcllivefor the History of tlle Exact Sciences, II (I965),

344-364; Anneliese Maier, An der Grenze von Scllolastile utld Naturwissenscllaft, 2nd ed.

(Rome, Igs2), 2Ig-2s4, esp. 236 ff.

59 This is in accord with the general thesis of Thomas S. Kuhn, The Strtlsture of ScientJVc

Revolutions (Chicago, Ig62), esp pp. 77-go.




CHARLES B. SCHMITT

105

One rnight be ternpted on the basis of this passage to argue that Zaba-

rella has forrnulated a clear distinction between experimentum and ex-

perientia. As we have seen the latter terrn appears to have a consistent

rneaning of 'intelligent personal experience or observation of the exter-

nal world', and, as such, it is clearly applicable to the resolution of dis-

putes in natural philosophy. Experimentum, in the passage cited above

and with reference to the rnedieval background, seerns to rnean a hypo-

thetical 'thought experirnent', with possible overtones of occultism.60

I do not think, however, that we can insist on this latter point, since I

have been unable to find additional passages in Zabarella's writings

where experimetatum is used; and it is not safe to base a whole interpreta-

tion of this term on two instances of its use in a single context. More-

over, all of this indicates that experimentum does not function as a central

technical terrn in his philosophy in the way in xrhich experientia might

be said to do.

What does emerge frorn this analysis of Zabarella is that experience

does play an irnportant role in his philosophy and that a number of the

exarnples which he gives of its actual functioning are well chosen and

very rnuch to the point. What apparently is lacking here, however, is

that he does not consciously seem to use experientia to test a particular

theory. When atternpting to decide on the truth or falsity of a particular

theory or hypothesis, Zabarella does sornetirnes bring forth inforrnation

gained frorn previous experiences or observations, which bears on the

problern at hand. What he apparently does not do, however-and this

rnust certainly be a key ingredient in any 'experimental rnethod' is

consciously, and with forethought, atternpt to test a particular theory

or hypothesis by devising a specific experirnent or observational situa-

tion by which to resolve the question. The distinction here is perhaps

sornewhat subtle, but, to my mind, it is a crucial one. The borderline,

between (I) a science based upon experience of tlle natural world and

(2) a science which is experirnental, involves (at least) the fact that in

case (I), one utilizes the experience which he has previously gained in

whatever way to settle problems, whereas in case (2), one consciously

devises a specific experi1nental or observational situation by which to

resolve a particular diffi1culty. In the first case, the experiential aspect,

which is utilized, is derived from what has been observed to have oc-

curred previously and is hence unplanned; in the second case, the experi-

ence which is considered to be relevant has been planned out before-

60 See the passage cited irl rl. I4, esp. p. I39.





hand. Consequently, in the second case, one decides the question at

hand on the basis ofthe results ofthe chosen observational experience.61

In short, experirnent necessarily involves foresight and planning; ex-

perience does not. This analysis would seern to indicate that Zabarella

can be called an empiricist with some justification, but he clearly is not

an experirnentalist, even in the rather vague sense of the word which

cornes out of the Baconian tradition.

III. GALILE0

A great deal has already been written concerning the importance which

Galileo attached to experirnent in his overall methodology and the ex-

tent to which he was au fond a Platonist, an Aristotelian, or an Archi-

rnedian.62 Although it is ternpting to read rnore modern conceptions

into his writings, and to see hirn through the eyes of Newton or of later

scientists, one rnust take great care to avoid doing this. The critic rnust

make every atternpt to evaluate Galileo's contribution in terms of his

own age and in terms of the problems with which he concerned hirn-

61 By this I do not imply that this distinction in itself is adequate for any detailed dis-

cussion of the problem of method as it applies to 20th-century science. I do feel, however,

that it is one of the most basic distinctions which had to be made before a genuine experi-

mental approach could evolve, and, consequently, one of the key distinctions which was

ernerging in the period we are here discussing. Zabarella may seem to approach the mod-

ern conception of experiment particularly with his observations on Monte Venda, but it

must be noted that there is no clear evidence to indicate that he actually planned the trip

to make the observations which he did. His trip might be sharply contrasted with the

more famous trip to Puy-de-Dome, initiated by Blaise Pascal in I648.

62 A good basic bibliography is to be found in A. C. Crombie, Robert Grosseteste . . ..

3o4n I . To this should be added Randall, The School at Padua . . .; Moody, op. cit.; Gilbert,

Renaissance Concepts of Method, pp. 230-23 I and passim; idef11, 'Galileo and the School of

Padua'; Carlo Maccagni, 'Esperienza tecnica e matematica nel metodo di Galileo

Galilei', in Actes du Symposium . . . (cited in n. 25) pp I67-I77; Bruno Busulini, 'Novita

metodologiche nel pensiero galileiano', Atti della Accademia delle Scienze di Torino, classe di

scienze matematiche e naturali, xcvu (I962-I963) 809-840; Emile Namer, 'L'intelligi-

bilite mathematique et l'experience chez Galilee', Revue d'listoire des sciences et leurs appli-

cations, xvrz (I964) 369-384; and Dominique Dubarle, 'La methode scientifique de

Galilee', Revue d'histoire des sciences et leurs applications, XVIII (I965) I6I-I90* Several in-

teresting papers have recently appeared in Ernan McMullin (ed.), Galileo Man of Science

(New York, I967; but issued I968)* These include Dominique Dubarle, 'Galileo's Meth-

odology of:lSTatural Science', 295-3I4; Thomas B.Settle,'Galileo's Use of Experiment as

a Tool of Investigation', 3 I 5-337; Edward W. Strong, 'The Relationship Between Meta-

physics alld Scientific Method in Galileo's Work', 352-364; and Thomas P. McTighe,

'Galileo's "Platonism": a Reconsideration', 365-387 For a more complete bibliography

of recent Galileo literature see Elio Gentili, BibliograJia galileiana fra i due centetlari (I942-

I964) (Venegono Inferiore [Varese], I966) which contains 979 items and Galileo Man

rr .

Oy oclence, 1- XXXll.




CHARLES B SCHMTT

107

self. Nearly all discussions about Galileo's rnethodology have rightly

focused upon his later works, particularly the Discorsi e dimostrazione

matematiche intorno a due nuove scienze (I638). On the other hand, very

little attention has been given to rnethodological rnatters with regard to

his earliest significant work, De motu, cornpleted at Pisa before he left

for Padua in I 592, but not printed until the nineteenth century.63 This

work, which deals with sorne of the sarne problems of mechanics wllich

he later treated in his rnature works, gives us an opportunity to study

his rnethodology as a young rnan of taventy-five or twenty-six years.

Furtherrnore, it makes it possible to study his thought before he carne

into direct contact with the tradition of rnethodological discussions at

Padua which culrninated in Zabarella. It is perhaps worth noting, at this

point, however, that Galileo's De motu is of the sarne scientific, literary

63 The date of the work seems to be I 589-I 592. See I. E. Drabkin, 'A Note on Galileo's

De moto', Isis, LI (I960), 27I-277. For further information on the work see Lane Cooper,

Aristotle, Galileo and the Tower of Pisa (Ithaca, I935), passim; Alexandre Koyre, Etudes

galileetlnes, I, 54-73; Raffaele Giacomelli, Galileo Galilei giovane e il suo 'De motu' (Pisa,

I949); Moody, 'Galileo, Avempace . . .'; A. Koyre, 'Le De motu gravium de Galilee: De

l'experience imaginaire et de son abus', Revue d7histoire des sciences et leurs applications, XIII

(I960), I97-245 [in this and what follows I will generally cite Koyre's articles from the

original sources, although most of them are now available in the following recent collec-

tions: Ettldes d'histoire de la pensee scientJique, ed. R. Taton (Paris, I966) and Metap11ysics

atld lkleasllrement: Essays in the Scientfic Revolution, ed. M. Hoskin (London, I968)];

Bruno Busulini, 'Componente archimedea e componente medioevale nel De motu di

Galileo', Physis, VI (I964), 303-32I; E. Grant, 'Aristotle, Philoponus, . . .' (cited in n.

54); Thomas B. Settle, 'Galileo's Use of Experiment . . .' (cited in n. 62); and the recent

English translation Galileo Galilei, On Motion and On Mechatlics, ed. I. E. Drabkin and

Stillman Drake (Madison, I960), pp. I-I3I. This latter work will hereafter be cited as

'Drabkin' with an indication of page number. The critical text of the De notu will be

cited from [Antonio Favaro, ed.], Le opere di Galileo Galilei (Florence, I929-I939), I,

243-4I9. Citations from the latter edition will hereafter be indicated by 'Opere', with the

volume number followed by the page number. If there is no 'Drabkin' reference, it will

indicate that the relevant section is missing from his [partial] translation. The translations

from the De n1otu cited in the text will be taken from Drabkin's translation where it exists,

although in the view of the present writer it is not always reliable. One crucial instance

where it is misleading will be discussed below. Unfortunately, this translation shows

every sign of becomirlg accepted by historians of science as an authentic substitute for the

original text. In addition to the translation being Lncomplete (e.g., I count nine of the

thirty-eight passages cited in the present paper as beillg absent from the translation), it

does not always convey the precise meaning of the original. Moreover, a distinguished

historian of science has recently endorsed this translation with high praise in our most ill-

fluential journal of the history of science. See the review of I. Bernard Cohen in Isis LVII

(I966), 50I-504, which claims (502) that the translation is 'faithful to the original which

it presents'. The reviewer actually quotes (502) apparently with a straight face and after

a comparison with the original text the very passage which I will show below to seri-

ously misrepresent the real meaning of the Latin text.





genre as Zabarella's already rnentioned De motu gravium et levium, which

certainly indicates a nucleus of common interests. In fact, treatises on

motion were very common in the writings of sixteenth-century natural

philosophers, and rnuch light could doubtlessly be shed on Galileo's

work by viewing it in relation to this tradition.

Although we cannot go into detail here, the De mota already seems to

manifest a highly sophisticated approach to tlle science of rnechanics,

and one which clearly points the way toward the Discorsi e dimostrazioni.

In the present study, we shall conftne ourselves principally to an allalysis

of his use ofthe notions of'experience' and 'experirnent', with a primary

focus on the De motu. We shall find that there are certain strong sirni-

larities to what we have already observed in Zabarella, but in other ways

we shall find in Galileo all approach rnuch different frorn Zabarella's.

Experientia is a frequently occurri1lg term in the De motu;64 the rnere

abundant use of the word is not decisive in itself, however, for cognates

migllt well be used to express the same idea.65 Without a doubt 'experi-

ence' does serve a key function in the work as a whole, and if one COll-

trasts it with a work such as Giambattista Benedetti's Disputatiofles de

quibusdam placitis Aristotelis,66 the difference is striking. Not only is 'ex-

64 A rough count gives eighteen occurrences in the I70 pages of text and two uses of

the verbal form experior.

65 For example Opere I, 252, 329, 336 (Drabkin, I4, IOI, I08-IO9).

66 This is contained in Benedetti's Diversaru1n speculationut11 mathematicarum et physi-

carum liber (Turin, I585), I68-I97. It was first printed as the preface to Benedetti's Reso-

lutio omnium problematuzn aliorllmqale llna tantummodo circHli data apertura (Venice, I553) and

reprinted a year later as Demonstratio proportioulasm motuunl localium cotltra Aristotelem

(Venice, I554). For the printing history and changes in the diffierent editions of Bene-

detti's work see I. E. Drabkin, 'Two Versions of G. B. Benedetti's Demonstratio propor-

tionunl motilum localium', Isis, LIV (I963), 259-262. On Benedetti and his influence see: G.

Vailati, 'Speculazioni di Giovanni Benedetti sul moto dei gravi', in his Scritti (Leipzig-

Florence, I9II), I6I-I78; G. Bordiga, 'Giovanni Battista Benedetti filosofo e matematico

veneziano del secolo XVI', Atti del R. Istituto lzetleto di Scienze, Lettere, ed Arti, LXXXV

(I925-I926), 585-754; Koyre, Etudesgaliletennes, I, 4I-54; idem, 'Jean Baptiste Benedetti,

critique d'Aristote', in Mctlaslges of erts a Etienne Gilson (Paris, I959), 35I-372. For further

information and bibliography see the article by V. Cappelletti in Dizionario Biografico

degli Italiani, VIII (I966), 259-265, which, however, ignores the important researches of

Koyre. The two following important works appeared after the present paper was essen-

tially completed: Carlo Maccagni, Le speculazionigiovatlili 'de motu' di Giovanni Battista

Benedetti (Pisa, I967) and idem, 'Contributi alla biobibliografia di Giovanni Battista Bene-

detti', Physis IX (I967), 337-364. The point of contact between Benedetti and Galileo is

their attempt to apply the mathematical methods of Euclid and Archimedes to problems

of mechanics. But, whereas Benedetti seldom refers to 'experience' in his work, Galileo

often does in the De mot". It should be noted, however, that an admonition has recently

been issued against connecting Benedetti too closely with Galileo. See I. E. Drabkin,




CHARLES B. SCHMITT

109

perience' important in the De motu, but it seems to serve as an adjunct to

the mathematical method of Euclid and Archimedes in a way which

Benedetti did not envision.

In the De motu there can be distinguished several diSerent uses of ex-

perlentia, which, of course, for the most part are deeply rooted in the

ancient, medieval, and renaissance traditions. First of all, and most fre-

quently, it is used in the somewhat non-technical way in which anyone

might use it in ordinary speech, viz. in the sense of 'experience teaches'

or 'experience shows us'. In short, certain things can be verified or not

verified by experiencing (or observing) the world aroulld us. This

seems roughly to be the way in which Zabarella thought of his own ex-

periences in most cases, although the acuteness and the care of his obser-

vations set him off from many of his contemporaries, as we have seen.

Moreover, we notice that when experientia is used in this sense by Gali-

leo it can function either in a positive or a negative way, i.e. it can either

support or fail to support a particular opinion or theory.

Experience functions in a positive way to show that nature has deter-

nwined the order of various bodies so that the heavier ones are situated

closer to the center of the world.67 ElsenThere experience is considered

to give a somewhat less definitive answer and only seems to show that

something is so.68 Much more frequently7 however, Galileo uses eX-

perientia to refute some commonly held position. For example, he re-

jects one of Aristotle's doctrines as follows:

Aristotle does not seem to be self-consistent. For lle says (De coeb 3.27): 'If what is

Illoved is neither heavy nor light, its motion svill be by force; and what is uloved by

force, and ofEers no resistance of lleaviness or lig;htness, moves without end.' And in tlle

next passagc lle says that proJectiles are carried along by the mcdium. But tllen, since

air llas neither weigllt nor lightness, once it is moved by the projector it will move

endlessly and always at tlle same speed. And it will consequently also carry aSong pro-

jectiles in endless motion, and will ncver be weakened, since it always Inoves witll the

same force. But experience sllows that the opposite of this happens.69

'G. B. Benedetti and Galileo's De mota.l', Proceeda1lgs of flle Tenl;l Inl;ernal;ional Congress of

tZae Hastory of Science (Paris, I64), pp. 627630, who points out some of the very real

diXerences between Benedetti's writings and the De mol;N.

67 'In hunc, itaque, ordinem a natura distributa fuisse corpora, ut? scilicet, quae gravi-

ora essent, celltro propinquiora manerent, continua nobis declarat experientia. Opere t?

344. For other examples see p. 334 (Drabkin, Io7) and the I"veltitia, in Opere I, 68, 84>

I64? I74-

68 Opere I, 329 Drabkn IO )

69 'Non bene sibi constare videtur Aristoteles. Nam 3° Caeli t. 27, inquit: Si quod

movetur neque grave neque leve fuerit, vi movebitur; et quod vi movetur, nullam gravi-





Again he invokes experience to show that the earth is not the heaviest of

all bodies: 'On the contrary, experience still teaches us regarding earth

that it is not the heaviest of all things, for it floats upon all of the liquid

metals, for example that which we call quicksilver. From which it fol-

lows that metals are heavier than earth itself.'70

One is struck by the numerous instances in which Galileo invokes ex-

perience in a negative way in the De motu. It seems as though even at an

early age, he was keenly aware that he was turning aside from many

corn1nonly held opinions, and he recurrently calls upon experieltia to

justify his uncommon stands.71 On the other hand, we should not place

too much emphasis on this, for the topics co+rered in the De motu were

highly contro+rersial, and he was necessarily at odds with many other

writers on the subject. In order to substantiate his own position in oppo-

sition to theirs, Galileo often finds it convenient to call upon experientia,

but at other times he uses other types of e+ridence such as ratio.

We can conclude then that Galileo often in+rokes experience to sup-

port his own argurllents and to question the opinion of others with

whom he disagrees. We must note, howe+rer, that upon occasion he

clearly states the limitations of experience and emphasizes the fact that

it is necessary that the natural philosopher also utilize other intellectual

techniques. This seems clearly e+rident in two passages whicll appear

early in the De motu. In the first of these Aristotle is criticized for relying

too much on experience in his analysis of the motion of bodies through

a medium:

Aristotle wrote (Physics 4.7I ) tllat tlle same body moves more swiftly in a rarer tllan

in a denser medium, and that therefore tlle cause of slowness of motion is the density of

tatis aut levitatis resistentiam habens, in inflnitum movetur. Textu autem sequenti inquit,

proiecta a medio ferri; cum igitur aer nec gravitatem habeat nec levitatem, a proiciente

motus in infinitum movebitur, et semper eadem velocitate; ergo etiam in infinitum

portabit proiecta, nec fatigabitur, cum semper eadem vi moveatur. Huius tamen con-

trarium experientia docet.' Opere I, 309 (Drabkin, 78).

70 'Nam de terra, quod non sit gravissima omnium, iam experientia docet: ipsa enim

metallis liquatis omnibus supernatat, ut argento quod dicunt vivo; ex quo patet, metalla

graviora esse ipsa terra.' Opere I, 360.

71 Other examples are: 'at contrarium accidere experientia docet.' Opere I, 330 (Drab-

kin, I02); 'experientia tamen contrarium ostendit'. Opere I, 334 (Drabkin, Io7); 'experi-

entia tamen contrarium ostendit'. Opere I, 356; 'contrarium etiam experientia docet'.

Opere I, 370; 'cuius tamen contrarium experientia demonstrat'. Opere I, 37I; 'et licet ex-

perientia contrarium potius interdum ostendat'. Opere I, 406; and in the Iuvenilia, in

Opere I, 49(2), 58, I30.




CHARLES B. SCHMITT

lll

the medium, and the cause of speed its rareness. And he asserted this on the basis of no

other reason than experience, viz. that we see a moving body move more swiftly in

air than in water. But it will be easy to prove that this reason is not sufilcient.72

Galileo then gives a variety of arguments, partially at least dependent

upon 'thought experiments', to show that the Aristotelian position is

incorrect. He concludes: 'Clearly, then, the statement of Aristotle that

slowness of natural motion is due to the density ofthe medium is inade-

quate. Therefore, dismissing his opinion, so that we may adduce the

true cause of slowness and speed of motion, we must point out that

speed cannot be separated from motion.'73 A clearer explanation of why

Galileo held that Aristotle's statement was 'inadequate' emerges a few

pages further on. Still discussing the problem of the motion of bodies

through a medium, he rejects Aristotle's view that a large heavy body

will move more swiftly through a medium than will a small heavy

body. He again postulates several 'thought experi1nents' derived largely

from common-sense, everyday experience, to show that Aristotle's

opinion is ridaculosa. After he has shown to his own satisfaction the in-

correctness of the Aristotelian position, Galileo continues by presenting

his own position. To his explanation he prefaces the following remarks:

'But, to employ reasoning at all times rather than examples (for what

we seek are the causes of effects, and these causes are not given to us by

experience), we shall set forth our own view, and its confirmation will

mean the collapse of Aristotle's view.'74 Consequently, for Galileo sci-

ence deals with the 'causes of effects' and these cannot be reached tllrough

experientaa-at least not through experientia alone.

Galileo's position on the matter seems to be the following. Experience

is often a useful device to resolve a particular dispute. By merely ob-

serving the world around us we can sometimes decide either for or

against a particular opinion which has been broug;ht forth. Therefore,

72 'Aristoteles igitur, 4Phys. t. 7I, scripsit, idem mobile citius moveri in medio subtiliori

quam in crassiori, et, ideo, tarditatis motus causam esse crassitiem medii, velocitatis autem

subtilitas; et hoc non alia ratione confirmavit nisi ab experientia, quia, nempe, videmus

mobile aliquod velocius moveri in aere quam in aqua. Verum hanc causam non sufficien-

tem esse, proclive erit demonstrare.' Opere I, 260 (Drabkin, 24).

73 'Manifestum est igitur, insufficienter ab Aristotele dictum fuisse, tarditatem motus

naturalis ob medii crassitiem contingere. Quapropter, ipsius opinione derelicta, ut veram

tarditatis et celeritatis motus causam affieramus, attendendum est, celeritatem non dis-

tingui a motu.' Opere I, 26I (Drabkin, 24-25).

74 'Sed, ut semper rationibus magis quam exemplis utamur (quaerimus enim eiec-

tuum causas, quae ab experieniia non traduntur), sententiam nostram in medium aiere-

mus, ex cuius comprobatione corruet Aristotelis opinio'. Opere I, 263 (Drabkin, 27).





Aristotle can sometimes be criticized for holding positions which are

not in conformity with experience.75 On the other hand, Aristotle

sometimes relies too much upon experience, to the extent that he does

not allow a suff1cient role to rationes; but according to Galileo, it is

through rationes that demonstration takes place. That is to say: demon-

stration and proof depend upon 'objects of thought' rather than 'objects

of experience'. In brief, demonstration in science follows a method very

similar to that used in mathematics, e.g. the method of Archimedes, al-

though the actual determining of the principles used in the demonstra-

tions are quite different.76 Consequently, one of Aristotle's major short-

comings was the fact that he was not well versed in geometry, being

'ignorant not only of the profound and abstruse discoveries of geome-

try, but even of the noost elementary principles of the science'.77 Ac-

cording to Galileo, this ignorance prevented him from developing a

more fruitful method than he did in natural philosophy. Consequently

Galileo wants none of this, but prefers to follow what he considers to be

quite a different rnethod:

The method tllat we shall follow in this treatise will be always to make what is said de-

pend on what was said before, and, if possible, never to assume as true that whicll re-

quires proof. My teachers of matllematics taught me this method. But it is not adhered

to suilciently by certaill philosophers who frequently, when they expound the ele-

mcnts of physics, make assumptions that are the same as those handed down in [Aris-

totle's] books On the Soul or those On the Heavefl, and even in the MetaWhysics. And not

only this, but even in expounding logic itself they continually repeat things that were

set forth in the last books of Aristotle. That is, in teaclling their pupils the very first

subjects, they assume that the pupils know everything, and they pass on to them their

teacIling, not on tlle basis of thin^,s that the pupils know, but on tlle basis of what is

completely unknown and unheard of. TIle result is that those who learn in this way

75See th text ctednn 69

76 Already in the De tnotu Galileo expresses enormous admiration for Archimedes:

'suprahumani Archimedis', Opere I, 300 (Drabkin, 67); 'divino Archimede', Opere I, 303

(Drabkin, 7I); 'divinissimi Archimidis' Opere I, 368. Koyre most strongly emphasized

the Archimedean element in Galileo: see especially his Etudesgalileennes I, 72-73, but also

Gilbert, 'Galileo and the School of Padua', 23I; Busulini, 'Componente archimedea e

componente medioevale . . .'; Eugenio Garin, 'Gli umanisti e la scienza', Rivista di Filoso-

fia, LII (I96I), 259-278, esp. 268, 277-278; and Marshall Clagett, Arctlimedes in the Middle

Ages, I: 'The Arabo-Latin Tradition' (Madison, I964), I.

77 'Aristotelem parum in geometria fuisse versatum, multis in locis suae philosophiae

apparet; sed in hoc potissimum, ubi asserit, motum circularem motui recto non esse pro-

portionatum, quia, scilicet, recta linea curvae non est proportionata aut comparabilis:

quod quidem mendacium (indignum enim est nomine opinionis), nedum intima et magis

recondita geometriae inventa, Aristotelem ignorasse, verum et minima etiam principia

huius scientiae, demonstrat.' Opere I, 302 (Drabkin, 70). However, see below n. 79.




CHARLES B SCHMTT

3

never know anything by its causes, but merely have opinions based on belief, that is,

because this is what Aristotle said. And few of them inquire whether what Aristotle

said is true. For it sufilces for them tllat they will be considered more learned, the more

passages of Aristotle they have ready for use.78

The method which Galileo here outlines as that which he has learned

from the mathematicians is not as different, as one might suppose, from

that outlined in the Posterior Allalytics.79 It is quite different, however,

frorn the method which Aristotle practiced in a work like the De coelo

which seems to be founded on a network of unsubstantiated assump-

tions.80 In the passage cited above, be it noted, it is the method practiced

by the Aristotelians, which comes in for the greater criticism, and not

that of Aristotle himsel£ What Galileo here seems to be advocating

more than anything else is the return to a method which begins with a

few well-founded first principles and from these establishes a strictly

deductive system similar to Euclid's.81 True science deals primarily with

causes and effects, logically related to one another in a deductive fashion

78 'Mcthodus quam in hoc tractatu servabimus ea erit, ut semper dicenda ex dictis

pendeant; nec unquam (si licebit) declaranda supponam tanquam vera. Quam quidem

methodum mathematici mei me docuere; llec satis quidem a philosophis quibusdam

servatur, qui saepius, physica elementa docentes, ea quae seu in libris De anima, seu in

libris De caelo, quin et in Metaphysicis, tradita, supponunt; nec etiam hoc suff>lcit, sed

etiam, docentes logicam ipsam, continue ea in ore habent quae in ultimis Aristotelis libris

tradita sunt; ita ut, dum discipulos prima docent, supponunt eos omnia scire, doctrinam-

que tradunt non ex notioribus, verum ex ignotis simpliciter et inauditis. Accidit autem

ita addiscentibus, ut nunquam quicquam per causas sciant, sed tantum ut fide credant,

quia, nempe, hoc dixerit Aristoteles. Utrum deinde verum sit quod dixerit Aristoteles,

pauci sunt qui quaerant: suff>lcit enim his, quod eo doctiores habebuntur, quo plures

Aristotelis locos prae manibus habobunt.' Opere I, 285 (Drabkin, 50-5I). It is not at all

clear that the phrase mathematici mei should be translated as 'my teachers of mathematics'.

Such a meaning is certainly possible, but it can as easily mean more easily on the basis of

the text we have 'my mathematicians', meaning the authors (primarily Greek) on

mathematics whom Galileo llad studied and admired. This is the way in which it is inter-

preted by Vincellzo Grimaldi, La mente di Galileo Galilei deslfnta principalmente dal libro

De nlotlfgravillln (Naples, I9OI), p. II8, a work which otherwise is of little value for an

understanding of the De motu.

79 The basic approacll of the Posterior Analytics, as well as many of the examples which

Aristotle uses in the work, is strongly gcometrical, reflecting Greek geometrical tradition

a few decades before Euclid. See H. D. P. Lee, 'Geometrical Method and Aristotle's Ac-

count of First Principles', Classical Qtlarterly, XXIX (I935), II3-I24.

80 Here the whole approach seems to be more matter of probability, less geometrical,

and more a product of experience. See James F. McCue, 'Scientific Procedure in Aris-

totle s De coclo, Traditio XVIII (I962), I-24.

81 See Opere I, 277-278 (Drabkin, 42), where he denounces one of Aristotle's supposed

'denlonstrations' for being based upon axioms (axiolnata) which are neither obvious

(aelantfesta) to the senses, nor demonstrated, nor demonstrable.





as the theorems of geometry are related to the axioms, postulates, and

definitions. In certain cases, on the other hand, Galileo recommends a

'resolutive method', or one which attempts to determine the cause of a

particular effect.82

Implicit in all of Galileo's uses of experientia is the assumption that the

observer plays merely a passive role: he does notproduce an experience,

but he has one. He is a mere observer in a world which can act upon

him in a variety of ways. These actions of the physical world upon the

receptive observer result in experience. Such a meaning is also obvious

when the notion of experience is expressed in its verbal form, experior.

For example, in discussing the transmission of force from one object to

another, Galileo asserts that those who play ball know by experience

that 'force is more strongly impressed on a body which presses forward

against it', and that one also experie11ces (experimur) the same thing

when he throws a stone.83

In conclusion, we can say that, although Galileo used the notion of

experie1ltia in several different ways and for several different purposes in

the De motu, all of these have a basic meaning of 'observation' or 'learn-

ing from the world what the world naturally presents to us' and defi-

nitely not the sense of'experiment' or 'purposefully testing some aspect

of physical reality'. Moreover, as far as I have been able to discover, he

does not use the word experimentum, which was used at times during the

late Middle Ages and Renaissance in senses approaching the modern

conception of'experiment',84 at all in the De motu.

82'Verum, caeterorum omissis sententiis, ut veram, quam credimus, huius effectus

causam indagemus, hac resolutiva methodo utemur'. Opere I, 3I8 (Drabkin, 88).

83 'Verum magis resistit quod contra nititur, quam quod aut quiescit aut ad eadem fer-

tur: in eo, ergo, quod contra nititur, arctius virtus imprimitur; quod experientia docti qui

follibus ludunt, ab aliquo contra se follem deici volunt, ut in eo reluctante et magis re-

sistente plus virtutis motivae imprimatur. Verum, ut iam diximus, id soli praestare pos-

sunt, qui robusto fortique brachio praediti sunt: qui vero languidi sunt viribus, nec contra

impetum niti possunt, contra quiescentem vel non ad contrarias tendelltem follem mo-

ventur; quod si ad easdem moveatur follis, paululum, ut quisque novit, impellitur. Cuius

effectus causa quidem est, quia quod quiescit, a maxima virtute percussum, movetur

antequam tota virtus imprimatur, cum illius mobilitas impressionem tantae virtutis non

expectet: quod non accidit in eo quod in contrarias [sic] cietur; nam, aucta per motum

suae gravitatis resistentia, magis resistit, nec ante totius virtutis impressionem retrocedit.

Et hoc idem experimur omnes, cum lapidem ante proicere volumus.' Opere I, 3 3 8 (Drab-

kin, III). See also Opere I, 264 (Drabkin, 28).

84 See for example, the text ofJohn Buridan cited from his Quaestiones super libris quat-

tuor de caelo et mundo in Marshall Clagett, The Science of Mechanics in the Middle Ages

(Madison, I959), p. 524, n. 39 and Grolamo Cardano, Opera Omnia (Lyon, I663), I,

360 (2 examples).




CHARLES B. SCHMITT

115

What we do find in the De motu, however,- and a point of some sig-

nificance which has not been previously noted, as far as I have been able

to determine is that Galileo appears to have a quite clearly worked out

conception of experiment, in the sense of 'testing nature'. This notion

he expresses, in a way which does not seem at all typical of his time, by

the wordpericulum. Althoughpericulum commonly expressed the notiorl

of 'test', 'trial', or 'experiment' in Classical Latin, these meanings seem

to have been later expressed increasingly by experimentum.85 Moreover,

the Italian form pericolo sems to have expressed 'test' or 'experiment'

only rarely; sperimento, esperienza, and cimento became the common

words to express this notion, both in Galileo's Italian works and in the

experimental tradition which came after him.86

Before we examine the use which Galileo made of periculum in the

De motu, several general observations are in order. We should first note

that, different from experientia, periculum [which might best be rendered

by 'test'] is apparently something that the investigator himself initiates

and controls in some way, viz, he 'activates' the situation. Somehow

85 For a clear example of periculum used to mean 'experiment' see Cicero's In Pisonem

XX5lii, 65 (Fac huius odii tanti ac tam universi periculum, si audes). This text is translated

by a recent editor as follows: 'Test by experiment this bitter and widespread hatred, if

you dare.' Cicero, The Speeches, ed. N. H. Watts (London: Loeb Library, I93I), p. 2I9.

The same translation is suggested by R. G. M. Nisbet in his edition of the work (Oxford,

I96I), p. I28. In Plautus' Asinaria, III, 3, one of the characters in speaking of love says:

'Scio qui periculum feci', i.e., 'I, who have tried it, know'. Other examples are to be

found in Lewis and Short's Dictio1lary and Mario Nizoli's Lexicon Ciceronianum.

86 The only example I have been able to find is in Giordano Bruno's De gli eroicifurori

v: 'la quale finalmente non tanto per far pericolo di sua gloria', in Dialoghi Italia1li, ed.

Gentile-Aquilecchia (Florence, I958), II73, where the editor correctly explains it in a

note. In my opinion, the recent English translation [Giordano Bruno's The Heroic Frenzies,

trans. Paul Eugene Memmo, Jr. (Chapel Hill, I964), 263 ] miscontrues this passage. The

Focabulario degli Accademici della Crusca (Florence, I69I) gives no instance which approxi-

mates the way in which Bruno uses it, nor do any of the other Italian dictionaries which

I have been able to consult. It is interesting to note, however, that the Focabulario gives as

Latin equivalents for cimeelto (II, 336) the following: 'periculum, experimentum, tenta-

mentum'.

Although I have not investigated this in detail, it is obvious that esperienza, sperimento,

and sperimentore are commonly used in Galileo's later Italian works. These also became

the standard words in the Galileian tradition of the I7th century in Italy. See, for exam-

ple, the material in Le opere dei discepoli di Galileo Galilei, I (L'Accademia del Cimento)

(Florence, I942). In the Latin translation of these experiments, which gained European

distribution, experimentum is used to translate esperienza. See Tentamina experimentorum

naturalium captorum in Academia del Cimento . . . Ex italico in latinum sermonem conversa.

Quibus commentarios, nova experimenta, et orationem de methodo instituendi experimenta physica

addidit Petrus van Musschenbroek (Leiden, I73I). See ntl. I02 and I3I below.




CHARLES B. SCHMITT

117

but nowhere, at least in his early works, does he suggest the possibility

of actually carrying out an experiment in a vacuum.89

More interesting are several other places where Galileo makes use of

the notion ofpericulum. The first such passage occurs in his discussion of

the ratios of the velocity of bodies of various specific gravities, moving

in media of various densities. After treating the question in wholly

theoretical terms without recourse to observation, Galileo adds:

Tllese, then, are thc gencral rules governing the ratio of the speeds of [natural] motion

of bodies of the sanle or of different material, in tlle samc medium or iIl diScrent

media, and moving upward or downward. But note that a great difElculty arises at tllis

point, because those ratios will not to be observable [literally: will turn out not to be

obsbrved] by one wllo malces the experiment [pericullntfecit]. For if one takes two dif-

ferent bodies, whicll have such properties that the first should fall twice as fast as the

second, and if one then lets them fall from a tower, the first will not reach the groulld

appreciably faster or twice as fast.90

Here the author clearly states that there is a discrepancy between theory

and what would be the observed result of an experiment or a test.91 Ac-

cording to the actual result of the experiment and in opposition to the

theoretically predicted result at the beginning of the fall, the lighter

body li.e. wood] 'will move ahead of the heavier [i.e. lead] atld be

swifter'. The further discussion of this he puts offuntil later,92 but not

before noting that the observed results of the experiment disclose noth-

ing but 'contradictory and, so to speak, unnatural accidents'.93

Later on, he discusses the matter in detail and attempts to solve the

89 See Koyre, 'Le De motu gravium . . .', pp. 2II-2I2^ We should note, however, the

following interesting passage which deals with the determination of precise weights and

which is couched in wholly theoretical terms: 'Quod si in vacuo ponderari possent, tunc

certe, ubi nulla medii gravitas ponderum gravitatem minueret, eorum exactas percipere-

mus gravitates.' Opere I, 276 (Drabkin, 40). On Galileo's position regarding the void

problem see especially his corl̂ espondence with Giovanni Battista Baliani and DeWaard,

op. cit., 93-IOI.

90 'Hae, igitur, universales sunt regulae proportionum motuum mobilium, sive eius-

dem sive non eiusdem speciei, in eodem vel in diversis mediis, sursum aut deorsum mo-

torum. Sed animadvertendum est, quod magna hic oritur diSlcultas: quod proportiones

istae, ab eo qui periculum fecerit, non observari comperientur. Si enim duo diversa

mobilia accipiet, quae tales habeant conditiones ut alterum altero duplo citius feratur, et

ex turri deinde demittat, non certe velocius, duplo citius, terram pertinget.' Opere I, 273

(Drabkin, 37-38). Cf. Koyre, 'Le De nlottl . . .', p. 227.

91 The wording seems to indicate that again we have a 'thought experiment' rather

than an actual physical one.

92 See Opere I, 3 3 3-3 3 7 (Drabkin, I 06-I I O) .

93 'Quae quidem diversitates et, quodammodo, prodigia unde accidant (per accidens

enim haec sunt), non est hic locus inquirendi'. Opere I, 273 (Drabkin, 38).





problem already posed. Although theory would make us conclude that

lead will fall faster than wood, experience will not corroborate this. As

he says:

But experience shows us the opposite. For it is true that wood moves more swiftly

than lead at the beginning of its motion; but a little later the motion ofthe lead is so

accelerated that it leaves the wood bellind it. And if they are both let fall from a high

tower, the lead moves far out in front. This is something I have often tested [perictelum

eci]. Therefore we must try to derive a sounder explanation on the basis of sounder

hypotheses.94

Here 'experiment' or 'testing' plays a very important role. It serves the

function of deciding that a particular hypothesis is not correct that it

literally does not 'save the phenomena'. Whether Galileo did actually

make such tests as he claims to have done 'often', of course, cannot be

verified.95 Even if he did, the results that he got (i.e. that wood at first

94 'Experientia tamen contrarium ostendit: verum enim est, lignum in principio sui

motus ocius ferri plumbo; attamen paulo post adeo acceleratur motus plumbi, ut lignum

post se relinquat, et, si ex alta turri demittantur, per magnum spatium praecedat: et de

hoc saepe periculum feci. Firmiorem igitur causam ex firmioribus hypothesibus ut hauria-

mus, tentandum est'. Opere I, 334 (Drabkin, I07).

95 The bulk of the evidence seems to indicate that he did not. See the material cited in

n. I23 . Thomas B. Settle, 'Galileo's Use of Experiment . . .' interprets the evidence of the

De motu in a way almost completely contrary to that of the present article. Professor Set-

tle sees the De motu as being based almost completely on experimental evidence, and, in-

deed, believes that Galileo's 'experimentalism' was already very much in evidence during

the Pisa period. In reading his article after the present study had been completed, I have

found that he presents no new and compelling evidence to make me change my interpre-

tation. I have had many fruitful conversations with Professor Settle over the past several

years, which have helped to elucidate many points regarding Galileo and early modern

science, but I fear that we are in fundamental disagreement on several crucial points, in-

cluding the following: (I) In how far are Galileo's claims to have utilized encperiefltiae to

be accepted at face value; (2) How much credence is to be given to the testimony of

Viviani; and (3) How far is thepossibility for Galileo to perform a given experiment to be

taken as evidence that he actually did perform it?

On the problem of actually performing an 'experiment' to discredit the Aristotelian

position see S. Toulmin and J. Goodfield, The Fabric of the Heavens (London, I96I, cited

from Penguin ed., London, I963), pp. I08-IO9. Galileo's statement that 'wood moves

more swiftly than lead at the beginning', but that lead later passes it, is somewhat baffling.

See Settle, art cit., 325-326, who is also puzzled by this text, but who analyzes it very per-

ceptively. Dr. Donald R. Miklich of the Children's Asthma Research Institute and Hospi-

tal in Denver has recently made a most valuable suggestion (in a private communication).

Dr. Miklich argues that if one attempted the experiment of dropping a lead and a wooden

ball simultaneously especially if he had been holding the two for some time to line them

up accurately, for example , then the muscular fatigue would be greater in the hand

holding the heavier object. This would result in his being unable to release the lead ball as

quickly as the wooden one and, consequently, he would see the wooden ball move ahead





119

moves faster than lead, but that the lead then later passes it) seem some-

what irnprecise, if not wholly incorrect. These questions we cannot go

into here. What is irnportant for the present discussion is that Galileo at

this point seerns to be saying that the theoretical structure of his science,

viz. the hypotheses, can be modified on the basis of a deliberately pro-

duced test or experirnent. The fact that the test has produced an unex-

pected result, and one not in conformity with the prediction based upon

theory, forces us to formulate 'sounder hypotheses'. Here the periculum

has served as a check for theoretical prediction.

This particular passage seerns to be the high water mark of experi-

rnentalisrn in the De motu. As we have already seen in another case in

which Galileo had invoked periculum, it sornetimes turns out to lead to

no solution at all. The fact that a periculum upon occasion leads to an

aporia is further illustrated by an additional passage, which also clearly

delineates the very real distinction between periculum and experientia to

which Galileo holds in the De motu. It occurs in the context in which he

discusses the inclined plane experirnents, which will later play such an

important role in the Discorsi:

And our demonstrations, as we also said above, must be understood of bodies free from

all external resistance. But since it is perhaps impossible to find sucll bodies in tlle

realm of matter, one who performs an experiment [periculum faciens] on this subject

should not be surprised if tlle experiment fails [si experientiafrustretur], that is, if a large

sphere, even though it is on a horizontal plane cannot be moved with a minimal

force.96

of the lead one. It may well be that Galileo and others (e.g. Girolamo Borri, as Settle,

325-326 suggests) tried this experiment with the result described. If such is the case, it

must be noted that Galileo states that after the wood is initially ahead, 'a little later the

motion of the lead is so accelerated that it leaves the wood behind.' One can now raise the

question of whether Galileo actually observed such a thing to happen. It seems highly

unlikely that he did, for it is diSlcult to imagine under what circumstances it would ac-

tually happen that the lead would pass the wood. The inescapable conclusion is that, if

Galileo, for the reason suggested by Dr. Miklich, saw the wooden ball move ahead of the

lead one, his further statement of the lead ball passing the wooden one at a later stage was

based lvholly on theoretical considerations, rather than experimental or observational ones.

That is, although Galileo saw the lighter object move ahead of the heavier, he knelv on the

basis of his fundamental hypothesis concerning the nature of light and heavy bodies that

the lead ball would overtake the wooden one. Here again attempted experiment is sub-

verted by a priori theory. Call it Platonic if you like or give it another name, but the

conclusion seems unmistakable.

96 'Et haec quae demonstravimus, ut etiam supra diximus, intelligenda sunt de mobili-

bus ab omni extrinseca resistentia immunibus: quae quidem cum forte impossibile sit in

materia invenire, ne miretur aliquis, de his periculum faciens, si experientia frustretur, et

magna sphaera, etiam si in plano horizontali, minima vi non possit moveri'. Opere I,





Here Drabkin's translation is misleading and has obscured a crucial point

by rendering two quite different Latin words (periculum and experientia)

by 'experiment'. Consequently, the point which I have been trying to

make fails to come across. In order to make Galileo's argument intelli-

gible the beginning of the second sentance must be rendered as follows:

'But since it is perhaps97 impossible to find [bodies free from external

resistance] in matter,98 anyone who performs an experiment concern-

ing these things should not be surprised99 if the [resulting] experience100

disappoints ... .101

Two thillgs of major importance clearly emerge frorn tllis text. First,

there is a sharp distinction betweenpericulum and experientia. The first is

something which one consciously and purposefully performs (or, in the

case of a 'thought experiment', conceptually 'performs') [facit] with

forethought and reason. Experientia, on the other hand, as we have seen

in many other passages, is something which acts UpOll a passive observer.

In this context, experie1itia refers to the observable result, which is re-

ceived in a passive way after one has actively performed the experiment.

The chain of events can, therefore, be stated as follows: (I) one per-

forms a periculum, (2) there comes from this a particular resultant phe-

nomenon and, (3) this phenomenon acts to bring about an experientia

in the one who started the chain by performing thepericulum. This anal-

ysis also helps to further clarify the other passage referred to above

where experientia and periculum were used together.102 Secondly, and

30>30I (Drabkin, 68). That the demonstrations involve an idealized situation is again

reiterated shortly afterwards: 'Sed, ut saepius diximus, hae delllonstrationes supponunt,

nulla esse extrinseca impedimenta, seu mobilis figurae, seu plani aut mobilis asperitatis,

seu medii in contrarias aut in easdem partes moti, seu extrinseci motoris virtutis urgentis

aut retardantis motum, et similia: de his enim accidentibus, eo quod innumeris modis

accidere possint, regulae tradi nequeunt'. Opere I, 302 (Drabkin, 69). Cf. Koyre, Etudes

galiletennes, I, 72-73.

97 The meaning offorte may be better expressed in this context as 'accidentally' or

'through no fault of ours'.

98 I.e., in the physical wrld of nature.

9Orshoudnot wnder

100 I.e., the result ofthe experiment, which the experimenter observes or 'takes in' as an

experience deriving from the planned periculum which lle has performed.

101 I.e., it fails to turn out as one might have predicted or fails to produce the sougllt-

after result.

102 See the text cited in n. 94. Although Galileo's use of periculunl is somewhat unusual

in such passages it is by no means unique. One example of its use during the period is to

be found in Nicander Iossius, Tractatus novus utilis et iucundus de voluptate et dolore, somno

et vigilia, dequefame et siti (Frankfurt, z603), pp. 5O5I, in a work first printed at Rome in




CHARLES B. SCHMITT

121

perhaps more important for the general understanding of Galileo's atti-

tude toward experi1nent in the De motu, this text definitely indicates

that some highly significant aspects of reality are not approachable

through experiment. Although we can design a test or an experiment to

resolve the point in question, the resulting experientia does not neces-

sarily disclose to us what we want to learn. In short, it 'disappoints' usX

The rcason that it fails to supply the needed information is that, in ma-

teria, we are not able to find an ideal body which will have no external

resistance. It is perhaps rlo accident that the text which we are discussing

corales immediately after one of the most Archimedean sections of the

work, wherein Galileo speaks almost poetically in an otherwise

straightforward scientific treatise of covering himself with the 'pro-

tecting wings of the superhuman Archimedes, whose name I never

mention without a feeli1lg of awe',103 and of 'geometric lice1lse (geo-

I580. Here we read in the section, De volHptate et dolore opllsclulluln: 'Quid tum de contin-

uitatis solutione, potest ne aliquis dutitare ne ab illa etiam fiant insignes dolores? culn

illud pateat experimento, videmus enim sive per incisionem aut puncturam, erosionem

vel contusionem, aliove quovis modo fiat haud mediocres, sed pene intolerabiles fieri

dolores, quorum nemo est, ut arbitror, qui in se ipso periculum non fecerit, ratio vero

illa, quoniam soluens continuam realem passionem inurit sensitivo corpori gravemque

laesionem corrumpentem partis naturam, quippe quae sua natura est una.'

A more significant example occurs in Sanctorius Sanctorius, De st:at:ica medicina (Leip-

sig, I670), f. A4V, in the Prefatory Letter to the Reader, which begins: 'Novum atque in-

auditum est in medicina posse quempiam ad exactam perspirationis insensibilis pondera-

tionem pervenire; nec quisquam philosophorum, nec medicorum unquam hanc medicae

facultatis particulam aggredi ausus est. Ego vero primus periculum feci et (lliSi me fallat

genius) artem ratione et triginta annorum experientia ad perfectionem deduxi, quam

consultius judicavi doctrina aphoristica, quam diexodica describere. Primo ad imitationem

magni nostri dictatoris, cujus vestigiis insistere gloriosum semper duxi; deinde id feci,

quasi necessitate impulsus quandoquidem ipsa experimenta, quibus quotidie assiduis

multorum annorum studiis incumbebam ....' Here, it is interesting to note, experient:ia,

experimentuna, and periculum are all used in the same passage. This should be studied with

greater care, but it would take us too far afield to do so here. On Santorio, who studied

medicine and philosophy (with Zabarella ) at Padua from I575 to I582 and took a medi-

cal degree in the latter year, see especially A. Castiglioni, La vit:a e l'opera di Sant:orio San-

t:orio capodistriazlo (1561-1636) (Bologna, I920: authorized English trans. by Emilie Recht

in Medical Life, n.s. I35 [New York: December, I93I], 727-786) and Mirko Drasen

Grmek, Sant:orio Sant:orio i njegovi aparat:i i inst:rument:i (Zagreb, I952), with English

suIllmAry, 79-82

The fact that both of these examples are found in medical writings may suggest that the

term was commonly used by medical authors of the late I6th and early I 7th centuries. In

Galileo's case it may be a carry-over frorn his early medical studies. This pOillt must be

investigated further elsewhere. See also below, n. I3I.

103 'His responderem, me sub suprahumani Archimedis (quem nunquam absque ad-

miratione nomino) alis melnet protegere'. Opere I, 300 (Drabkin, 67).





metricam licentiam'.l04 It is perhaps a consequence of Galileo's 'geometric

license' that makes it necessary for him to consider certain problems of

motion to be unresolvable throughpericulum and experientia and to con-

clude that they must be studied in theoretical terms rather than in ma-

teria. After all he has before him the sound geometrical methods of Ar-

chimedes and Benedetti to serve as models. Just as points, lines, and sur-

faces are not strictly speaking encountered in materia, so neither are

'bodies free from all external resistance'.

Finally, one further passage clearly illustrates some of the shortcom-

ings of periculum as a technique for solving problems of the sort en-

countered in the De motu. This occurs in a section of the original manu-

script which was later cancelled and which is relegated to a footnote in

the critical edition. Although Galileo may have thought better of these

lines after he had first written them down, as far as his use ofpericulum is

concerned, they are in substantial agreement with the other passages of

the De motu which we have cited above. In the context of his considera-

tion of the downward motion of bodies through a medium he says:

Moreover, ofthe three media through which motion occurs, fire is much too far away

from us, and since we can only perform an experiment [periculum facere], which has to

do witll motion downward, in air for those things which are close to us are all heavier

than air-therefore we shall verify our demonstrations in a medium of water; for we

have some bodies which descend in water, and likewise certain ones which when low-

ered in water, seek the top. Nevertheless, those things wllich have been shown con-

cerning water and concerning objects moving in water, are also true concerning the

other two media, namely air and fire. However, they have been shown by Archimedes

to be similar, by means of the demonstrations which I shall cite-nevertheless, other

things having been sulDstituted, otller media adopted into the demonstrations. Since all

these tllings are purely mathematical, they will be demonstrated by me through more

pllysical arguments because tllese will apply more directly to that which is the present

task.l05

The upshot of this is that certain classes of interesting and significant

104 Ibid Cf Koyre, Etudesgalileennes, I, 72.

105 'At quia, ex tribus mediis per quae fiunt motus, ignis a nobis nimium distat, cumque

in aere non nisi de motu deorsum periculum facere possimus; ea enim, quae apud nos

sunt, omnia aere sunt graviora; ideo in medio aquae demonstrationes nostrae verifica-

buntur: habemus enim corpora nonnulla quae in aqua descendunt, et item aliqua quae,

in aquam demissa, sursum petunt. Attamen [eriam cancelled] ea quae de aqua ostendentur

et de mobilibus in ea, vera sunt quoque de aliis duobus mediis, aeris nempe, et ignis.

Demonstrationibus autem quas [ms.: quae] afferam, similes demonstratae sunt ab Archi-

mede; attamen aliis suppositis, aliis mediis in demonstrationibus adsumptis. Quae omnia

cum sint pure mathematica [ms.: matematica], a me rationibus quibusdam magis physicis

demonstrabuntur; eo quod magis conferent ad praesens negocium.' Opere I, 380n.




CHARLES B SCHMTT

physical phenomena are not directly accessible to a test or experiment;

although some things can actually be tested, others cannot. Againpericu-

lum is discovered to have a very limited field of application. However,

Galileo here makes a most striking suggestion. By means of an analogy

one can sometimes apply experiment to realms of inquiry not directly

accessible to experimentation or testing. Galileo's appeal to analogy in

the De motu is something which should be explored more carefully, but

it would take us too far afield to do so here. We shall merely mention

that it is a procedure which is not without its dangers.106

The result which emerges from analysis of the De motu is, first of all,

that Galileo already had some notion of experiment (in the sense of con-

sciously attempting to 'test' the natural world in such a way that the ex-

perimenter has an active role, in so far as he imposes a certain structure

upon nature with the aim of obtaining a particular result). Secondly,

this type of experimentation can be clearly distinguished from an ex-

perience in 7hich one plays merely the passive role of an observer of the

events around him. Thirdly, although experiment is a clearly worked

out notion in the De motu, it in no way represents a 'new philosophy' or

the beginning of a new era as far as Galileo is concerned. In fact, from

what he tells us, more often than not experiment and experience serve a

negative rather than a positive function. Experience often tells us that

commonly held opinions are incorrect; experiments sometimes fail to

provide us with the information we expect to gain from them. If Galileo

is proud of having found a new and different approach to the problems

of natural philosophy, it is more likely that it is the method of the ge-

ometers than an experimental method.107

IV CONCLUSIONS

Let us now attempt to sum up the results of our investigation. We shall

address ourselves primarily to three different matters: (I) a comparison

of the young Galileo with Zabarella regarding their conceptions of 'ex-

perience' and 'experiment'; (2) the implications of our analysis with re-

106 See especially Koyre, 'Le De motum gravium de Galilee . . .', ed. cit.

107 Galileo draws a clear distinction between 'mathematical'and 'physical'explanation:

Opere I, 257 (Drabkin, 20).Even what he calls a 'physical' approach is not an experimental

one, but primarily a theoretical discussion which deals with physical entities, as we see

from the section of his work which follows, i.e., where he is specifically approaching the

subject physice.





gard to a more complete understanding of Galileo's methodology; and

(3) a consideration of some of the wider philosophical and historical

mp 1catzons ot our 1nvestlgatlon.

What immediately emerges, when one compares Zabarella with the

young Galileo, is that, although the latter has recourse to experience

more frequently than the former, the very concept of experience has a

much more central role in the former's philosophical and scientific

methodology. Zabarella might almost be characterized as an 'empirical

Aristotelian' in the sense that experience is almost always utilized to cor-

rolDorate and verify the philosophical and scientific positions of Aristotle.

Moreover, experience, as Zabarella understands it, is not always of an

indefinite and vague type (i.e. as in the phrase, experietItia docet), but it

often involves careful and highly-trained observations gained only after

one has had some extensive contact with the subject matter being studied

through experiential methods. With the young Galileo, on the other

hand, experience is not always so carefully selected and, more often

than not, proves to be deceptive or, at least, not capable of resolving the

problem at hand at least with regard to the subject about which he

chose to write his most extensive early work, i.e. motion. In that partic-

ular inquiry other methods, those of applied mathematics and of ra-

tional analysis, are formd to have more fruitful results. Galileo's system-

atic use of esperietIza lies in the future and does not seem to emerge in a

coherent fasllion much before his Discorso itItorYlo alle cose che stazzzlo izz sx

I'acqua of I6I2.

This major difference which we find between the two thillkers seems

to stetn from the entirely different ways in which they viewed the

world. Zabarella, following Aristotle and the long Aristotelian tradi-

tion, saw it as a living, biological entity, teleologically oriented and best

understood through experience and syllogistic reasoning. Galileo, orl

the other hand, saw the world in mathematical terms, composed of geo-

metrical figures which move in conformity with mathe1natically ex-

pressible laws and best understood through the modes of mathematical

analysis. It would be diS1cult to overemphasize the significance of this

distinction when one is faced with the evolution of seventeenth-century

science. Zabarella, though he may have had a more sophisticated and

more highly developed attitude toward experience and observation-

at least toward the actual practice of observation than the pre-Paduan

Galileo, nevertheless failed, as nearly all previous members of the Aris-

totelian tradition had failed, to appreciate the significance of mathemat-




CHARLES B SCHMTT

ics for understanding the physical world.l08 Galileo, while perhaps

oriented toward an idealized, Platonic view of the universe, was able to

avoid the extravagances to which that tradition was usually prone109

and to champiotl a new way of thought which he developed even more

successfully in his years of maturity.

In line with this it is perhaps worth noting that the Renaissance Aris-

totelians' conception of examen metItale or Ylegotiatio, to which certain

historians have attached so much sigrlificance,1l0 loses some of its force.

Both Galileo and the Aristotelians saw the same world before thern; it is

only when they began to consider it, to cogitate upon it, that a clear

difference emerges. No amount of'mental examination' ever seetned to

get the Aristotelians beyond the impedimetIta of Aristoteliarl fvxrts to a

clearly conceived, idealized world ill which motion and change could

be considered in mathematical terms. Although 'mental examination'

perhaps gave the Aristotelians a clearer notion of specific cause-effect

relationships, it still didn't solve the real problem of fitting a changing

nature into a mathematical model. Galileo although in the De motu he

had not yet developed his method fully is already able to analyze his

problems without recourse to a specific doctrine of examezz nlentale by

following the method he had learned from his mathematici. The moral of

108 There has been a conjoining of mathematical with philosophical interests upon rare

occasions among the Aristotelians, primarily with some of the I4th-century French and

English natural philosophers. A rare Italian example is Blasius of Parma. The general

situation becomes most apparent when one considers how few of the Isth- and I6th-

century commentators and translators, who concerned thelaselves with ancient mathe-

matical works, were Aristotelians.

109 The differences between Galileo's 'Platonism' and other varieties of Platonism are

shown by Ernst Cassirer, 'Galileo's Platonism', in M. F. Ashley Montague, ed., Studies

and Essays in t11e History of Science and Learning O ered in Homage to George Sarton on the

Occasion of tlis Sixtieth Birthday (New York, I944), 279-297. Cf. Garin, Scienza e vita

civile nel Winascimeslto (Bari, I965), p. I57. There has been a good deal of discussion re-

cently on the point of Calileo's 'Platonism'. See especially the papers of McTighe and

Strong cited above in n. 62 and Cassirer's 'Mathematical Mysticisln and Mathematical

Science', trans. by E. McMullin for Galileo Man of Science, 338-35I [originally in Lychnos

V (I940), 24S-265, as 'Mathematische Mystik und Naturwissenschaft']. Both McTighe

and Strong argue against calling Galileo a 'Platonist'. The argument is largely sterile at

this point. What is evident is that Galileo did accept certain positions identified more

closely with the Platonic tradition (broadly conceived) than with any other major philo-

sophical tradition, but he quite obviously did not accept all tenets of all Platonists. I have

not yet been able to see M. Clavelin, La pllilosophie natllrelle de Galilete (Paris, I968). Ac-

cording to the publisher's advertisoment the collclusion of this book is optilllistically

'Finalement l'idee d'un Galilee platonicien apparait pour ce qu'elle est: un mythe.'

110 See the works of Randall and Edwards cited above





this is that 'mental examination' in itselfis not so important as possessing

the proper method by which to know how to examine. The proper

method at least as far as physics is concerned, turned out to be a mathe-

matical one, not a teleological one.

Another major difference of outlook between Zabarella and Galileo

lies in the fact that Zabarella's primary motive was to understand, expli-

cate, and substantiate the philosophy of Aristotle; and he found experi-

etItia to be a helpful aid in doing this, although perhaps no more helpful

than philology or the totality of earlier Aristotelian commentaries then

available to him.1ll The fact seems undeniable, however, that his chief

task as a philosopher at Padua was to understand Aristotle; this was the

fizzal cause of his philosophical endeavors, as it were. The assumption

present in this, of course, was that if Aristotle was understood, the world

and reality could also be understood; but, nevertheless, the accurate un-

derstanding of Aristotle was the primary task. With Galileo the situation

was entirely different; he had no such commitment to an understanding

of Aristotle. At the time the De motu was written he was a teacher of

mathematics and had a much less clearly defined task than a philosopher

had with several centuries of institutional philosophical tradition behind

him. If anything, Galileo's task was to understand and explicate Euclid

and Ptolemy, the two authors whom we know he covered in his lec-

tures. In the De motu, which seems to represent a sort of extra-curricular

activity, he must be considered something of a 'free lance' investigator

with no doctrinal commit1nent, as it were. As a teacher of mathematics

he leaned heavily toward the methodology of Euclid and Archimedes,

it is true, but, as an investigator of questions concerning the motion of

heavy and light bodies, he was essentially searching for a new approach

to a problem i.e. motion which had for centuries fallen within the

province of the Aristotelian-Scholastic philosophers. He thus shows a

more 'open' attitude toward introducing non-traditional elements into

his investigation. As we have seen he considered a mathematically-

Oriented approach to be more fruitful than an experientially oriented

one.

What has been compared in this paper is the function of experience

and experiment in the practice of science which we find in the writings

of the two thinkers. By this, I mean that Zabarella has been considered

1ll The case with Zabarella seems to have been essentially the same as Professor R. W.

Southern has pointed out that it was with Grosseteste and Roger Bacon. See A. C. Crom-

bie, ed., ScientHc Change (London, I963), pp. 30I-306, esp. 304.





127

insofar as he actually faces questions of natural philosophy, as distin-

guished from his theoretical discussions of methodology to be used in

these matters. In the corpus of Zabarella's writings are some works (e.g.

the Commentary on the Posterior Analytics, De methodis, and De regressu) in

which he reflects upon the proper methodological procedures to be fol-

lowed in solving a problem of natural philosophy; in others (e.g. De

regionibus aeris and De motu gravium et levium) he actually attempts to

solve some of the problems themselves. Our inquiry has focused upon

how he practices science in the latter type of work rather than upon how

he theorizes about it, for we have considered it more appropriate to

compare his actual practice of science with Galileo's practice as illus-

trated in the De motu.

As we have already noted, experience has a more central and a more

positive function to play in Zabarella's practice of science than in Gali-

leo's at least insofar as we can know it from the fragmentary informa-

tion which survives during the Pisan period. It is also obvious from

the material which we have studied that Zabarella exhibits a far greater

knowledge of technology and uses it to a much greater extent in his

scientific discussions than does the young Galileo. Of Galileo's change in

orientation with regard to this we shall say more below. However, it

must be pointed out here that Zabarella does not appear to be the ivory

tower academic, innocent of experience and of knowledge of technol-

ogy, as characterized one is tempted to say 'caricatured' by Zilsel

and others. On the other hand, during his early life, at least before going

to Padua, Galileo shows little or no knowledge, insofar as information is

extant about him, of technology and crafts.1l2 In short, then, Zabarella

much more clearly points the way toward seventeenth-century experi-

mental observational science, rooted in the earlier traditions of'magic

and experimental science' and of technology, than does Galileo during

his pre-Paduan period. If experitnent and observation are to be consid-

ered the crucial ingredients of 'modern science' a point of view which

the present writer does not endorse Zabarella must be considered a

much more significant precursor of that movement than the young

Galileo.

The defenders of the 'schoc)l of Padua' ,uvaos might argue that once

Galileo got to Padua and breathed the free air, unsullied by clericalism

and authoritarianism, he too was able to extend the range of his experi-

ence and to find for it a more important role in his thought. Here we

112 See below for a fuller discussion of this.





find at least a grain, and perhaps more, of truth, but we must not over-

emphasize the radicalism there,1l3 when Galileo joined 'Padua1ls' such

as Francesco Piccolomini (of Siena), Cesare Cremonini (of Cento), and

Bernardino Petrella (ofBorgo San Sepolcro), the philosophers at Padua

in I 592. How he must have felt at home with Piccolomini and Petrella,

who shared his Tuscan origin as well as his dissatisfaction with certain

elements ofthe current Aristotelian logic 1l4

Although there may be some disagreement as to what at Padua made

it happen, even our limited investigation seems to indicate that Galileo's

attitude toward the importance of experience in the study of science did

change quite significantly during his years in Padua. This leads us into

our second point: what are the implications of our present study for an

understanding of Galileo's methodology? Although it is beyond the

scope of the present paper to study the matter exhaustively, it may not

be out of place to briefly discuss the question of Galileo's change in

orientation with regard to the methodology he practiced in his scien-

tific studies. As we have already 1nentioned several times, there are

widely divergent interpretations of Galileo's general intellectual Wel-

tanschauung, viz. whether he was fundamentally a Platonist, an Aristo-

telian, an Archimedean, or an engineer who generalized some of his

specific experience. From what we now know it is obvious that he was

ill one way or another indebted to each of these traditions: his vision of

the universe and of the nature of number are strikingly Platonic in cer-

tain respects; some of his specific tecllniques, as well as the terms which

he uses to describe them; e.g. metodo risolutivo and metodo counpositivo, as

well as his general appeal to experience, seern in all probability to be-

113 Eugenio Garin, Scienza e vita civile nel Winascimento itazliano (Bari, I965), p. I79 ob-

serves: 'La filosofia della natura di Telesio non conquisto gli Studi [di Padova], come non

vi penetro nessuna delle posizioni veramente dinamiche del Cinquecento. Ne la situa-

zione di Padova, con buona pace di certi storici, era diversa de quella di Pisa.' See my re-

view of this important book in Internafional PSiilosophical Qllarterly VIII (I968), 297-303 .

114 Vincenzo Viviani wrote in his Wacconto (Opere, XIX, 602): 'Ud, i precotti della

logica da un Padre Valombrosano; ma pero que'termini dialettici, le tante definizioni e

distinzioni, la moltiplicita delli scritti, l'ordine et il progresso della doctrina, tutto riusciva

tedioso, di poco frutto e di minor satisfazione al suo esquisito intelletto.' This must be

read with the same caution as other sections of Viviani's work (see below n. I23), but

there are passages in Galileo's writings from all periods of his life which clearly state his

dislike of Aristotelian logic. For the polemic betsreen Zabarella and Piccolomilli and

Petrella see Pietro Ragnisco, 'La polemica tra Francesco Piccolomini e Giacomo Zabarclla

nella Universita di Padova, Arti del R. Islstitllto Feneto, ser. VI, IV (I885-I886), III9-I252,

and idem, 'Una polemica di logica nell Universita di Padova nelle scuole di Bernardino

Petrella e di Giacomo Zabarella', ibid., ser. VI, IV, 4635o2.




CHARLES B SCHMTT

perhaps quite unconsciously derived frorn Scholastic Aristotelianism;

the general tecllnique of applying rnathernatical analysis to problerns of

physics owes rnuch to Archirnedes; and his developrnent of instrurnents

and his practical knowledge of the crafts certainly derives froin the en-

gineering tradition with which he was dernonstrably acquainted. Cas-

sirer, OlsclAi, Koyre, Randall and others have broken the ground for a

comprehensive study of Galileo's rnethodology, but much rernains to

be done. A rnajor desideraturn in Galileian studies at the present tirne is

to have a comprehensive study of his rnethodology with a full treatrnent

of the rnajor elernents which went into it as well as its Entwicklungs-

gescltichte traced through the extant writings. It is not out of the question

that these various elernents rnight have becorne adopted at various

stages of his career, forrning, as it were, several layers of the rnature

methodology of the Due nuove scienze and Discorsi e dimostrazioni.

The rnethodology of the De rnotu in particular and of the pre-Paduan

period in general betray a predorninant dependence upon the mathe-

matical approach of Archirnedes. This is evident from the rnaterial cited

in the present paper, which illustrates Galileo's very limited conf1dence

in experience and experiment for the study of natural science. Another

point, one which we have not studied here, is that the De motu attempts

to treat the dynamic problern of rnotion by developing a systern analo-

gous to the approach used by Archimedes in the static problerns of the

lever (or balance), particularly with regard to floating bodies.1l5 As Ar-

chimedes worked out the laws of bodies (statically) floating in a liquid,

Galileo tried to work out the analogous, but more complicated situation

of solid bodies (dynamically) moving through a fluid medium.1l6

With few exceptions, all of the extant evidence points to the fact that

Galileo's consuming interest before he went to Padua was his study of

mathematics. Leaving aside the so-called Iuvetlilia,1l7 which are appar-

115 The present writer plans to discuss this topic more fully in a paper on Galileo's use

of models and allalogies in the De motu.

116 This is quite apparent, for example, in Opere I, 254257 (Drabkin, I7-20). Galileo's

approach here is certainly less formal than that which we find in Archimedes' On Floating

Bodies, but it must be remembered that the De motu does not have the character of a com-

pleted work; it is rather more in the nature of a preliminary draft.

117 Printed in Opelre I, 9-I77. The precise significance of these notes has not yet been

determined. Most Galileo scholars are of the opinion that they do not represent his origi-

nal thought, but are merely his professors' (especially Bonamici's) teachings which he

copied down. It is possible, however, that they with the logic Quaestiones might represent

an early Aristotelian phase against which he later reacted violently, e.g., in works such as

the De motu, as Giacomelli, op. cit., 6I2, seems to suggest.





ently the notes made by Galileo while attending classes in Aristotelian

philosophy, and the unpublished Quaestiones on logic,1l8 also Aristotel-

ian in the most traditional way, Galileo's pre-I5g2 writings are all

strongly oriented toward a matherrlatical approach to knowledge.1l9

118 See Opere IX, 279-282, 29I292 for a discussion of these Quaestiones, a listing of the

topics treated, and a sample question. These were excluded from the National Edition of

the Opere. It is hoped that a complete edition of them will be forthcoming shortly. It is

essential to study this material with greater care if we are to have a clearer understanding

of Galileo's methodological sources. It is presently MS. Galileo 27 of the Biblioteca

Nazionale of Florence. For descriptiolls see, in addition to the pages in the Opere, cited

above, A. Procissi, La collezione galileiana della Biblioteca Nazionale di Firenze, I (Rome,

I959), I06-I07. Among the authors whom Galileo cites in the Quaestiones are; Themis-

tius, Philoponus, Algazel, Avicenna, Averroes, Thomas Aquinas, Albertus Magnus, Caie-

tanus, Zimara, and Balduinus. The mentioning of the last three (e.g., f. 29V) indicates that

Galileo had at least some acquaintance with important Italian Aristotelian thinkers from

Padua, even during his Pisan period. The importance of this manuscript becomes even

more crucial for the resolution of the problem of the relation of Galileo to the Aristotelian

movement, when we note that the Tertia disputatio (fs. 29r-3 IV) is entitled 'De speciebus

demonstrationis' and that the Quaestio tertia of this has the title of 'An detur regressus

demonstrativus' (fs. 3 I r3 IV). It is unfortunate that Favaro omitted this material from his

edition, but since he has done so, we must not fall into the trap of following his judgment

as to its 'unimportance', as Gilbert seems to have done. See his 'Galileo and the School of

Padua', p. 224.

119 These include: La bilancetta (Opere I, 2II-220) of I586, the first extant work in

Italian and one which shows its dependence upon Archimedes even from the opening

sentence; a list of esperienze carried out with the balance (Opere I, 223-228); the Theore-

mata circa centrum gravitatis solidorum (Opere I, I 8 I-208) of I 5 87, also clearly under Archi-

medean influence; and some annotations on Archimedes' De sphera et cylindro of about the

same time (Opere I, 23 I-242).

In addition to these works of scientific and mathematical interest from the pre-Padua

period, we have also several works of primarily literary orientation. These include Due

tezioni all'accademiaforentina circa lafgura, sito egrasldezza dell'itlferno di Dante (Opere IX,

3I57) and his satirical poem, Capitolo contro ilportar la toga (Opere IX, 2I3-223). In the

first of these Galileo attempts to determine certain physical characteristics of Dante's In-

ferno, but rather than basing his estimates on observation and experience, he realizes that

a different approach is necessary: 'Se e stata cosa diSlcile e mirabile . . . l'aver potuto gli

uomini per lunghe osservazioni, con vigilie continue, con perigliose navigazioni, misu-

rare e determinare gl'intervalli de i cieli, i moti veloci ed i tardi e le loro proporzioni . . .

quanto piu maravigliosa deviamo noi stimare l'investigazione e descrizione del sito e

figura dell'Inferno, il quale, sepolto nelle viscere della terra, nascoso a tutti i sensi, e da

nessuno per niuna esperienza conosciuto . . .' (p. 3I). The method to be used again turns

out to be that of Archimedes: 'Ma volendo sapere la sua grandeza rispetto a tutto l'aggre-

gato dell'aqqua [sic] e della terra, non doviamo gia seguitare la opinione di alcuno che

dell'Inferno abbia scritto, stimandolo occupare la sesta parte dello aggregato; pero che

facendone il conto secondo le cose dimostrate da Archimede ne i libri Della sfera e del

cilindro, troveremo che il vano dell'Inferno occupa qualcosa meno di una delle I4 parti

di tutto l'aggregato' (p. 34). The whole approach to this problem is mathematical and

one might observe that, not only is 'the book of nature' written in mathematical terms,

but, in this case at least, the 'book of the supernatural' is as well. Whereas we might ex-




CHARLES B. SCHMITT

1 31

Moreover, all of Galileo's extant correspondence frorn the pre-Paduan

period, which does not concern personal rnatters, deals with rnathemat-

ics.120 Essentially the only scholarly topic discussed by Galileo and his

correspondents in the early letters which have survived is mathenlatics.

His early writings reveal that not only was his primary concern with

mathematics, but with early that is to say, Greek mathematics: Ar-

chimedes, Euclid, Eutocius, and Pappus are the mathematicians dis-

cussed.

The only documentary evidence which we have of a direct concern

with or knowledge of any sort of craft tradition during the pre-Paduan

period is to be found in his La bilancetta. Here Galileo appends a brief

descriptiotl at the end of the treatise on just how the balance might be

constructed.12l The table of data which he derived from utilizing his

pect the analysis to contain some elements ofthe technology and craftsmanship so vividly

and graphically portrayed by l)ante himself in the description of the inferno, they are

wholly absent. Rather, the point of departure, besides Archimedes, is from Euclid's Ele-

ments: '. . . se tale Inferno fosse una intera sfera, sarebbe una delle mille parti di tutto

l'aggregato, come da gli Elementi d'Euclide facilmente si cava' (p. 48).

Although his poem, strictly speaking, contains nothing to allow us to decide whether

Galileo was, at that time, experimentally or mathematically oriented, one might draw a

certain significance from the following passage, jocose as it may be:

'Perche, secondo l'opinion mia,

A chi vuol una cosa ritrovare,

Bisogna adoperar la fantasia,

E giocar d'invenzione, e 'ndovinare;

E se tu non puoi ire a dirittura,

Mill'altre vie ti posson aiutare

Questo par che c' insegni la natura,

Che quand'un non puo ir per l'ordinario,

Va dret' a una strada piu sicura.' (pp. 2I3-2I4)

For further information on the purely literary aspects of Galileo's works and his influence

on Italian literary style see especially Enrico Falqui, 'Galileo Galilei e la prosa scientifica

del Seicento', inLetteratura italiana: Iminori, I (Milan, I96I), I523-I572, where further

bibliography will be found. For a valuable summary of Galileo's Florentine background

literary and intellectual see Eric Cochrane, 'The Florentine Background of Galileo's

Work', in Galileo Man of Science, pp. II8-I39.

120 Opere x, 22-50. This includes correspondence with Christophorus Clavius (2 let-

ters by Galileo, 2 by Clavius), Guidobaldo dal Monte (one by Galileo, I2 by Guidobaldo),

and one letter in Latin to Galileo froln Michael Coignet, a luathematician at Antwerp.

121 Opere I, 2I9-220. The description here is quite detailed, even going into how to

overcome some of the practical diSlculties which may be encountered in constructing a

balance. One does not find any such practical hints in the writings of Archimedes which

have come down to us. The Pseudo-Archimedean work, De insidentibus in humidum,

however, gives a number of practical details, as do other medieval treatises on weights.

See Ernest A. Moody and Marshall Clagett, eds., The Medieval Science of Weights (Madi-




132 TWO TERMS IN ZABARELLAANI) GALILEO

bilancetta does indicate a certain incipient experimentalism on his part and

probably represetlts his closest approach, before moving to Padua, to

what later became 'experimental science'. There is, it is true, a passage

in Viviani's Racconto istorico della vita di Galileo which attributes to him a

great technological and manual prowess even at an early age.122 This

passage, however, was written by Viviani in I654 about events which

had occurred seventy or eighty years previously (i.e. forty years before

Viviani's birth) and must be considered subject to the same doubts

which scholars have expressed regarding Galileo's supposed observa-

tions of a 'sanctuary-lamp pendulum' and the supposed 'leaning tower'

experiments at Pisa.123 Consequently there is no strong evidence to

support the view that Galileo's primary methodological motives de-

rived from his knowledge of the technological, craft tradition and from

detailed experience of natural phenomena. His early orientation was

essentially mathenlatical; all that he wrote between I584, the date of his

first acquaintance with mathematics, and I 592, when he went to Padua

for a new career, confirms this.

His orientation seems to have changed quite significantly in the course

of his eighteen years at Padua. During this time he built his own tele-

scope, he visited the Arsenal and the shipyards of Venice, his house took

on the characteristics of a craftsman's workshop, and he began writing

treatises both of a more practical and of a more experimental cast. One

should perhaps not dramatize this change in attitude too much, but even

the first letter extant from his Paduan period illustrates this. In this doc-

son, I952), pp. 40-53, esp. definitio I, p. 40. As Moody points out in his introduction (p.

39) this work was printed in the I6th century, but was not attributed to Archimedes ex-

cept in a French translation of I565. Blasius of Parma's Tractatus de ponderibus (Moody

and Clagett, ed. cit., pp. 229-279) gives numerous practical details, e.g., p. 275.

122 'Comincio questi [i.e., Galileo] ne' prim'anni della sua fanciullezza a dar saggio

della vivacita del suo ingegno, poiche nell'ore di spasso esercitavasi per lo piu in fabbri-

carsi di propria mano varii strumenti e machinette, C011 imitare e porre in piccol modello

cio che vedeva d'artifizioso, come di molini, galere, et anco d'ogni altra maccllina ben

volgare. In difetto di qualche parte necessaria ad alcuno de' suoi fanciulleschi artifizii

suppliva con l'invenzione, servendosi di stecche di belena in vece di molli di ferro, o

d'altro in altra parte, secondo gli suggeriva il bisogno, adattando alla macchina mlovi

pensieri e scherzi di moti, purche non restasse imperfetta e che vedesse operarla.' Opere

XIX, 60I . Gherardini's Vita (Opere XIX, 63 3-646), however, strongly emphasizes Galileo's

great love for mathematics during the time he was at Pisa (pp. 636-637).

123 Opere XIX, 603, 606. For a summary of the problems see Giacomelli, op. cit., 6-I2.

See also Lane Cooper, op. cit.; Antonio Favaro, 'Sulla veridicita del "Racconto istorico

della Vita di Galileo" ', Archivio storico italiano, LXXIII (I9I5), 323-380; idem, 'Di alcune

illesattezze nel "Racconto istorico della Vita di Galileo" ', ibid., LXXIV (I9I6), I27-I50.




CTTAn TEC1 C-TT\fTTT

JlALiJ1 . i tJllVl 1 1

133

ument, addressed to Giacomo Contarini and dated 22 March I593,

Galileo discusses the practical problem of the motion of a ship (not the

motion of theoretical bodies through theoretical media as in the De

tnotu).l24 Moreover, the first works which have come down to us from

the Paduan period, the Breve instruzione all' architettura militare and the

Trattato difortificazione, assignable to the academic year I592-I593, deal

with one of the most practical of all Renaissance disciplines, military

engineering.125 The next work from his pen, Le meccaniche of I597-

I598, gets back to a somewhat more theoretical approach, but still has

strongly practical overtones, evidenced already by the title of tlle open-

ing section: 'Delle utilita che si traggono dalla scienza mecanica e dai

suoi instrumenti.'l26 About the same titne as he was working on the

Meccaniche, he became increasingly interested in and involved with the

Copernican theory, a concern which dominated much of his later life

and which, among other things, led him to develop the telescope. It was

also during the Paduan period that he came to have more confidence in

esperiealza as a technique of scientific investigation. As Stillman Drake

has recently pointed out, Galileo's mature methodological views first

appear in the Discorso intorno alle cose che stanno in su l'acqua o che in quella

si muovono (written in I6II, printed in I6I2), 'in which experiments are

designed for and applied to the refutation of verbal explanations and

arguments'.127 In this work his polemic is still against Aristotle,128 as it

124 Opere x, 55-57. After a long involved discussion, Galileo says: '. . . et tutto questo

e manifestissimo per l'esperienza' (p. 57) . A further avenue of exploration with regard to

Galileo's dependence upon experience, and one which remains largely unstudied, is the

empirical musical background of his father Vincenzo Galilei. Careful study could perllaps

elucidate whether Galileo was influenced by Vincenzo's attitude toward music. Much

important material is collected by Claude V. Palisca, 'Scientific Empiricism in Musical

Thought', in H. H. Rhys, ed., Seventeenth Century Science a>d the Arts (Princeton, I96I),

pp. 9I-I37. See also Olschki, op. cit., III, I35-I39. Dr.J. R. Ravetz has called this material

to my attention; his illcisive criticisms of an earlier draft of this paper have added im-

measurably to its improvement.

125OpereI 7-46-

126 Opere II, I55. The treatise opens as follows: 'Degno di grandissima considerazione

mi e parso, avanti che discendiamo alla speculazione delli strumenti mecanici, il conside-

rare in universale, e di mettere quasi inanzi agli occhi, quali siano i commodi, che dai

medesimi strumenti si ritraggono: e cio ho giudicato tanto piu doversi fare, quanto (se

non m'inganno) piu ho visto ingannarsi l'universale dei mecanici . . . perche, quando

niuno utile fusse da sperarne [i.e., of the science of mechanics], vana saria ogn; fatica che

nell'acquisto suo s'impiegasse' (pp. I55-I56).

127 In his article 'Galileo Galilei', Encyclopedia of Philosophy (New York, I967), III,

262-267, at 26sb. The work is printed in Opere IV, 5-I4I.

128 'E perche la dottrina che io seguito nel proposito di che si tratta e diversa da quella





had been in the De motu, and, moreover, his pro-Archimedean orienta-

tion seems to have lost none of its force.129 However, he seems content

not only to show that Archimedes' positions are true by virtue of rea-

son, but also that they are in accord with esperienza.l30 Experience much

less frequently has the dubious nature which it had in the De motu, but

rather it acts as a positive aid in developing scientific truth.13l This

treatise seems certainly to mark a turning point in Galileo's career, at

least with regard to his development of a methodology for the study of

problems of dynamics. Here for the first time the mathematical-Archi-

medean approach developed in the De motu is coupled with a more

positive attitude toward experimentation and the manual ability to

actually carry out the necessary experimental procedures. The latter ele-

d'Aristotile e da' suoi principii, ho considerato che contro l'autorita di quell'uomo gran-

dissimo, la quale appresso di molti mette in sospetto di falso cio che non esce dalle scuole

peripatetiche, si possa molto meglio dir sua ragione con la penna che con la lingua, e per

cio mi son risoluto scriverne il presente discorso: nel quale spero ancor di mostrare che,

per capriccio, o per non aver letto o inteso Aristotile, alcuna volta mi parto dall'opinion

sua, ma perche le ragioni me lo persuadono, e lo stesso Aristotile mi ha insegnato quietar

l'intelletto a quello che m'e persuaso dalla ragione, e non dalla sola autorita del maestro

. . .', Opere IV, 65. Cf. pp. 80-86 where there is an extended refutation of positions ad-

vanced in Bonamici's De motu.

129Eg bd p 67-

130 '. . e sara l'una e l'altra esperienza molto ben concorde alla dottrina d'Archimede

. . .', ibid., p. 82; '. . . potremo con sicurezza dire, la dottrina d'Archimede esser vera,

poiche acconciamente ella s'adatta alle esperienze vere . . .', ibid., p. 83.

131 'Ma perche tali cose, profferite cosl in astratto, hanno qualche diSlculta all'esser

comprese, e bene che vegniamo a dimostrarle con esempli particulari: e, per agevolezza

della dimostrazione, intenderemo, i vasi, ne'quali s'abbia ad infonder l'acqua . . .', ibid.,

p. 7I; '. . . qualunque volta noi vogliamo far prova di cio che operi circa questo effetto la

diversita della figura, sara necessario far l'esperienza con materie nelle quali la varieta delle

gravezze non abbia luogo . . .', ibid., p. 88. The second passage cited above is interesting in

so far as it seems to distinguish betweenfarprova andfar l'esperienza,something we cannot

discuss in detail here. For the present context, however, it is perhaps of interest to note

thatfacere periculum may be the Latin usage behind the former. We find periculum and ex-

perifelentum given as Latin equivalents for prova in Giacomo Pergamino, II memoriale della

lingua italiana (Venice, I6I7), p. 434 and Vocabolario degli accademici della Crusca, 2nd ed.

(Venice, I763), III, 529. Other relevant lexicographical information includes: Ambrosius

CaIepinus, Dictionarium in quo restituendo atque exornando haec praestitimus . . . (Venice,

I57I), II, 66VX which reads: 'Periculum . . . Aliquando accipitur pro experimento [Esperi-

enza, prova] . . .', and Luc'Antonio Bevilacqua, Vocabulario volgare et latino . . . (Venice,

I57I), 52r, which reads: 'Prova, et pruova, sperienza.] periculum, experimentum. pro-

batio. Far prova.] facere periculum.' A further interesting example, this time in a French-

Latin dictionary, is to be found in Robert Estienne, Dictionarium Latinogallicum (Paris,

I538), 533, which reads as follows: 'Periculum, periculi, Peril, Danger . . . Facere pericu-

lum, Faire l'experience de quelque chose, Experimenter, Esprouver, Essayer.'




CHARLE S B . S CHMITT 135

ment seems certainly to stem from his eighteen years at Padua, while the

former is a carry-over from his days in Tuscany. Our treatment of this

latter material has admittedly been sketchy and must be studied in

greater detail elsewhere.

Let us now briefly recapitulate. In the De motu of I589-I592, Galileo

made a clear-cut distinction between experientia (experience in a general

and passive sense) and periculum (experiment or test in a sense in which

the investigator takes an active role). However, both experience and

experiment (or testing) are of limited value, for they often fail to give

the information which is expected of them; a more theoretical, mathe-

matical approach, which can make use of idealized conditions, not acces-

sible through experiment, is necessary. After his eighteen years at Padua,

he gave a more important and more positive role to experiment, so that

the mathematically oriented approach of the De motu was conjoined

with controlled and carefully designed experiment, consequently pro-

ducing the famous 'scientific method' so apparent in Galileo's best

known works of maturity.

One final word regarding Galileo's peculiar term periculum. There

seems to be little if any trace of this word in Galileo's writings after the

De motu. Just why he abandoned it is not a question which we have

been able to answer. The distinction between experientia and periculum

which is so clear cut in the De motu, as we have seen, apparently becomes

lost in his later works, where the single term esperiealza is used, some-

times qualified as sensata esperiealza. This latter usage, however, does not

seem to have a clearly fixed meaning and does not always indicate a

sharp distinction from esperienza in the general sense. One thing which

Galileo's use of periculum-rather than experimentum, the preferred me-

dieval usage-seems to indicate is a turning back to antiquity rather

than to the Middle Ages for inspiration. This is admittedly a rather

minor instance of such a tendency in Galileo, but is by no means atypical.

In Galileo we find a strong tendency, ultimately an outgrowth of his

humanist heritage, to go back to ancient sources for materials for his

thought.132 It is not unlikely that periculum reflects this and the word ex-

perimentum represents to him a medieval form from which he would

prefer to dissociate himself. It is also possible that he disliked the occult

overtones which the latter word had, for quite differently from many

sixteenth- and seventeenth-century scientists Galileo seems to have rela-

tively little use for occultism, mysticism, and the pseudo-science of the

132 Eugenio Garin, 'Gli umanisti e la scienza'.




136 TWO TERMS IN ZABARELLAAN:) GALILEO

theologians.133 All of this, however, does not help to determine why

Galileo later abandoned the distinction. Perhaps as his attitude toward

'experiment' became more favorable; and as he worked out the details

of individual experiments in a more precise way, he felt that his verbal

explanation of experiments (e.g. of the inclined plane 'experiment' in

the Discorsi e dimostrazioni) was adequate in each individual case to dis-

tinguish between ordinary experience and scientific experiment.

Finally, what are some of the broader implications of our investiga-

tion? Although it seems obvious that the 'experimental method' which

errlerged in the seventeenth century was in some way or another all out-

growth of the observationalist and experientialist tradition of the pre-

ceding centuries, it is not at all clear precisely holv. To see it as 1nerely an

outgrowth of technological practice on the one hand or of Aristotelian

empiricism on tlle other, seems to oversimplify the situation to the point

of distortion.134 At the same time, one must be careful not to dismiss

entirely the significance of observation and experience and to make the

'scientific revolution' merely a conceptual revolution in which a Pla-

tonic view of the tuliverse replaced an Aristotelian one.l35 It seems

clearly to have been a more complex process than either of these inter-

pretations would seem to suggest. It is the belief of the present writer

that more light could be shed on this subject through a detailed study of

sixteenth-century writings on natural philosophy, both scholastic and

133 The case with Newton was, of course, different as is becoming increasingly appar-

ent. See especially J. E. McGuire and P. M. Rattansi, 'Newton and the "Pipes of Pan" ',

Notes and Records of the Royal Society of London, XXI (I966), I08-I43. Even Galileo, how-

ever, did not entirely escape from such influences, especially during the early part of his

life before I597-as much as the positivistically oriented historians of science would like

to lead us to believe he did. E.g., see the recent and influential book by Ludovico Gey-

monat, Galileo Galilei (Turin, I957; English trans. by Stillman Drake and Foreword by

Giorgio de Santillana, New York, I965). For a more accurate analysis of the situation see

Garin, Scienza e vita civile . . ., pp. I47-I70 (Galileo filosofo), esp. pp. I56-I58, I63, I67.

134 It must be noted, as has been pointed out by A. Koyre, 'An Experiment in Measure-

ment', Proceedings of t1ze American Philosophical Society XCVII (I953), 222-237, at 222-223

that the 'empiricism of modern science is not encperiential; it is encperimental' and that 'its

"empiricism" differs toto caelo from that of the Aristotelian tradition'.

135 In the opinion of tlle present writer Alexandre Koyre sometimes tended to do this.

Consequently, an empirically oriented thinker such as Gassendi, with only a limited in-

terest in mathematics and Platonic philosophy seems to be consistently underestimated.

See his Frolzz the Closed World to the Infiltite Universe (New York, I958), 290 and his paper

'Gassendi: le savant', in Pierre Gassendi: sa vie et son oeljvre, I592-I655 (Paris, I955), 60-

69, esp. 60. For the importance of Gassendi see especially Richard H. Popkin, The History

of Scepticisstfronl Erasmus to Descartes (Assen, I960), IOI-III, I42-I48 and Tullio Greg-

ory, Scetticisnzo ed entpirislo: studio su Gassendi (Bari, I96I).




CHARLES B SCHMTT

137

non-scholastic. A reading of the texts would undoubtedly hold many

surprises and could even invalidate the old excuse for not reading these

texts: viz. 'there is really nothing there, just the same old-fashioned

Aristotelianism.'136 The present investigation seems to reveal more than

anything else how little we really know of sixteenth-century philosophy

and science once we go beyond a few well-known figures, who are of-

ten not intrinsically the most important, but rather have certain ro-

mantic, national, or ideological associations to which attention has been

drawn.

The classical 'scientific method' which emerged in the seventeenth

century involves aborre all else two main factors: the application of

mathernatics and the use of experiment. The fornler was already in

possession of Galileo at Pisa, the latter he developed at Padua; the two

he colljoined ila his mature works. Consequently, the Galileo who be-

carrle a symbol to all parts of Europe in the seventeenth century emerged

only after he went to Padua. On the other hand, however, it is remark-

able how much of lasting signif1cance can be traced to Galileo's works

even before he arrived at Padua.137 Chiefamong these are (I) a realiza-

tion that nature must be read in mathematical terms and that a mathe-

matical method is eminently applicable to problems of natural philoso-

phy, and (2) the realization that there is a clear distinction to be drawn

between 'experience' and 'experiment', although the full potentiality of

136 In addition to the above analysis of Zabarella see my 'Gulio Castellani (I528-

I586): A Sixteenth Century Opponent of Scepticism', esp. 36, 39, where we see a I6th-

century Aristotelian siding with Lucretius to defeat scepticism. The present writer is not

at all certain whether Professor Randall's statement, viz. 'It is significant that the atomism

of Lucretius was always held at Padua to be crudely unscientific', Tlle School of Padua . . ..

p. 85, iS entirely accurate. I plan to publish elsewhere the evidence for the influence of

Lucretius and Atomism upon the Aristotelian natural philosophy of the Renaissance.

137 This, of course, disagrees fundamentally with the Cassirer-Randall thcsis, which

traces the dominant factors of Galileo's methodology to Paduan influences. I also find it

difilcult to see how the contention of William A. Wallace, op. cit., p. 263 n. 2 ('Galileo,

of course, studied at the School of Padua and learned his methods of investigation there.')

is to be substantiated. If anything, Galileo studied at the 'school of Pisa' and learned his

methods there. All too often in the literature, the 'School of Padua' seems to have an ideo-

logical, rather than a geographical reference-not wholly unlike the 'School of Hard

Knocks'. For an attempt to defend the Randall thesis against the substantial criticisms

which it has received see William F. Edwards, 'Randall on the Development of Scientific

Method in the School of Padua-A Continuing Reappraisal', in Naturalism and Historical

Understandislg: Essays isl the Philosophy of Jolln Herman Rasldall, Jr., ed. John P. Anton

(State University of New York Press, BuflHalo, I967), pp. 53-68. It sllould be noted that

later in his life Cassirer tended to see Galileo more as a type of'Platonist.' See for exam-

ple, his papers cited above in n. IO9.





the latter technique is not yet completely realized. In fact, esperienza is

never insisted upon by Galileo, even in the mature works, as a key

method for penetrating the riddles of nature to the extent that it is, for

example, by Bacon.138

University of Leeds CHARLES B SCHMTT

138 See Gilbert, Renaissance Concepts of Method, pp. 230-23I. There is much to be said

for Fr. Dubarle's argument that 'Galilee, contrairement, a ce que l'on dit souvent, n'est pas

charles schmitt experience and experiment

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