milton - origin and development of concept laws of nature 1981

J O H N R. M I L T O N

The origin and development of the conceptof the Haws of nature'

i

T H E I D E A of explaining natural phenomena by appealing tolaws of nature is one that is thoroughly familiar to the modern mind.This idea does not perhaps appear quite as natural as it did a centuryago, when Engels proclaimed to the mourners at Marx's funeral thatjust as Darwin had discovered the law of development of organicnature so Marx had discovered the law of development of humanhistory. Twentieth-century historians do not in general conceivetheir task as including the formulation of laws of history, and thediscoveries of modern physics since Maxwell have for the most partbeen expressed in terms of principles and equations rather thanlaws. Nevertheless, despite these changes, we are still quite accus-tomed to thinking in terms of laws of nature; and just because itseems natural it is easy to assume that it is natural for human beingsseeking to explain the phenomena of nature to do so by enquiringafter the laws by which these phenomena are governed.

It ought however to be clear to any reasonably attentive reader ofwhat survives of Greek science and philosophy that the Greeks didnot conceive of physical explanation in this way. There are two mainreasons why this is not always realised. One is that many modernwriters talk about laws in places where the Greeks themselves didnot: thus we find references in writers such as Marshall Clagett andS. Sambursky to Aristotle's laws of motion, to the law of the lever, tosublunary and celestial bodies obeying different laws, and so on (i).To avoid altogether expressions such as these is far from easy. Therecan be no doubt that historians of the standing of Clagett and Sam-

(i) Cf. the accounts of Aristotelian and Physical World of the Greeks (Londonlater dynamics in M. CLAGETT, Greek 1956), pp. 92-94 and The Physical WorldScience in Antiquity (New York 1955), of Late Antiquity (London 1962), pp. 62-70.pp. 64-72, 169-177, in S. SAMBURSKY, The

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Arch, turop. tociol., XXII (1981), 173-195 — 0003-9756/81/0000-0440 $02.50 © 1981 A.E.S.

JOHN R. MILTON

bursky are fully aware that they are using modern concepts as an aidin exposition, but their more innocent readers (perhaps largelyunacquainted with the original texts) might easily be misled.

A second and far more insidious danger is mistranslation. InThe Open Society and its Enemies, Sir Karl Popper quotes one of hisheroes, Democritus, as saying that he 'would rather find a singlecausal law than be the King of Persia' (2). How many of the numer-ous readers of that highly influential book are aware that there isnothing in the original corresponding to Popper's 'law' ? (3). To befair to Popper, even classical scholars are not always immune from thiskind of error: there are several instances in the Oxford translation ofAristotle, for example at Physics 253b2Jj, and De Generatione etCorruptione 336327.

By the time that we eliminate all these translational artefacts thenumber of genuine references in classical Greek thought to a law orlaws of nature can be seen to be very small indeed. If we excludethose that are concerned purely with morality rather than naturalscience there remain only one in the whole of Plato (4) and one inAristotle (5). Neither is typical. Plato was concerned with theworking of the human body, Aristotle with Pythagorean numbermysticism. Aristotle's own thought about nature is entirely freefrom legal concepts and even legal metaphors.

It is not difficult to discover why no distinct notion of a law ofnature ever came to be developed in the classical period. The sophistshad made the antithesis between nomos and phusis part of the mentalfurniture of the age, and any attempt that might be made to combinethe two and speak of a 'law of nature' would inevitably carry an airof self-conscious paradox. This artificiality is clearly present in thefirst surviving use of the phrase, by Callicles in the Gorgias, in thecourse of an argument to justify the rule of the strong over theweak (6).

Conceptual antitheses such as this frequently bring about a modifi-cation in the meaning of one or both terms. The contrast withphusis shifted the meaning of nomos in such a way that in many caseswhere it occurs the correct translation cannot possibly be 'law' butinstead must be 'convention' or something similar. Democritus,

(2) K. R. POPPER, The Open Society and sokratiker (Berlin 1903; 6th edition, rev.its Enemies (London 1945; 5th edition, W. Kranz, 1951. Henceforth cited as Diels-1966), vol. II, p. 27. Kranz), 68 B 118.

(3) A. [...] gAsye PoiiXeofiai liSAXov ixiav (4) Timaeus, &3e.eupstv aE-noAoytav ft •rtv Ilspooiv ot PaoiXelav (5) De Caelo, 268314.-fev£a6ai, H. DiELS, Die Fragmente der Vor- (6) Gorgias, 483c.

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for example, maintained that bitter, sweet, hot and cold exist nomd—byconvention, relatively to the human senses (7); and Empedoclesremarked that, though what men think of as birth and death are reallyonly the assembly and dispersal of pre-existing parts, nevertheless healso will continue to speak nomo—in accordance with the (mistaken)conventions of men (8).

The extent to which the antithesis was taken for granted amongthe educated can be seen from Aristotle's characteristically detachedaccount of how best to go about confusing your opponent in debate.This whole topic of nomos and phusis, he remarked, provides quiteexceptionally good ground for generating paradoxes: when youropponent starts talking in terms of nature, you reply in terms of law,and vice versa (9).

It is therefore hardly surprising that (apart from the one, verymarginal, passage in the De Caelo already mentioned) Aristotle neverused the notion of a law of nature at any point in all his scientificinvestigations or in the formal discussion of scientific method in thePosterior Analytics.

We can therefore say with certainty that the concepts of a (scien-tific) law of nature came into use at some time after Aristotle (10).It is also apparent that by the end of the seventeenth century the ideaof explaining natural phenomena by appealing to laws had becomefamiliar and generally acceptable, at least among the scientificallyeducated. We can see this from the supreme achievement of the age,Newton's Principia. The formal structure of Book I of the Principiais Euclidean, but there is one major difference. After the initialdefinitions and associated scholia, we find the next section headednot simply Axioms but Axioms or laws of motion (11). The oldfamiliar Aristotelian-Euclidean word and the new word stand side byside. Newton used the latter because it was appropriate but alsobecause it would be readily understood and accepted by his contem-poraries. In this he was certainly not mistaken. To give one exampleamong many, in the earlier discussions between Wren, Wallis, Huygens

(7) Diels-Kranz, 68 B 9. anticipates the science of Aristotle and(8) Diels-Kranz, 31 B 9. Archimedes, not of Descartes and Newton.(9) De Sophisticis Elenchis, 17337-18. (11) Isaac NEWTON, Philosophiae Natu-(10) Juridical notions do appear among ralis Principia Mathematica, edited by A.

the Presocratics in connection with nature, KOYIUS and I. B. COHEN (Cambridge 1972),e.g. in Anaximander (Diels-Kranz, 12 B 1) pp. 55-56. On the early drafts of thisand Heraclitus (Diels-Kranz, 22 B 94) but section, see I. B. COHEN, An Introductionthe thought is very unlike the later concep- to Newton's Principia (Cambridge 1971),tion. This line of thought, associating pp. 62-66.justice in nature with balance and harmony,

JOHN R. MILTON

and Oldenburg concerning the motion of colliding bodies the phrase'law of motion' was in constant use (12).

The change to the modern conception of a scientific law thereforetook place at some time between the late fourth century B.C. and theseventeenth century of our era. The questions which naturally nowarise are two in number. First when did the change occur and over(approximately) what space of time? Secondly what particularexplanation, and more generally what type of explanation can beprovided for it ?

It might seem that we ought to leave aside the second of thesequestions until we have answered the first. After all, explaining achange which has not even been securely dated appears to be a hazard-ous and indeed potentially futile proceeding. Dangers such as theseare certainly not to be despised, but it can be shown that the alternativeprocedure also has considerable, though less obviously visible, disad-vantages. Suppose, for example, that we decide to start by assem-bling as many references to laws of nature as we can find within theperiod from Aristotle to Newton. The resulting pile might be largeenough to dishearten all but hardened lexicographers, but that wouldbe one of the least of our problems. The real difficulty would be indeciding what ought and what ought not to be included. We mightdecide to include every occurrence of the phrase 'law of nature', lexnaturae, vojxo? ir\c, cpuosac, and their modern equivalents. This wouldclearly bring in many wholly non-scientific occurrences (particularlyof lex naturae); it would also clearly leave much out, especially whenthe qualifier 'of nature' is absent. Laws of motion are unquestionablyrelevant, for example. Again, should the occurrences of lex naturalis(usually found in moral and legal contexts) be omitted from such adeliberately Baconian initial survey ? Most perplexing of all is thequestion of what should be done with words which may or may notbe equivalent to lex and nomos. Thesmos (roughly, ordinance) oughtcertainly to be included in the Greek list, but what about logos or ius?Two examples, one ancient, one modern, should make clear the serious-ness of this difficulty.

Lucretius used the word lex on three occasions in connection withthe natural world, though scarcely in a modern sense (13). He alsoused foedus naturae on a further six occasions (14). Should theselatter be included ? The answer turns on whether the conceptual

(12) The Correspondence of Henry Olden- (13) De Rerum Natura, ii. 719, iii. 687,burg, edited by A. R. HALL and M. B. HALL v.58.(Madison 1967-), vol. V, pp. 103, 117, 125, (14) Ibid. 1.586, ii.302, v.57, 310, 924,167, 193, 221, 319-20, 358. vi.906.

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difference between foedus and lex is important or not, and this cannotbe established merely by studying the dictionary definitions of thetwo words.

Huygens also used a variety of words. On some occasions hefollowed Descartes in speaking of the laws governing collisions, butmore often than not he preferred to speak of regies or regulae. Is thedistinction of any significance? Sometimes, almost certainly it isnot. For example, in successive letters to R.F. de Sluse, Huygensreferred first to the rules and then to the laws of motion (15); it isunlikely that he intended to make a distinction of any kind. On theother hand, if we consider lex and regula to be equivalent in general,then, we create further difficulties, in particular with writers likeGalileo who use the latter expression (16) but not (in their strictlyscientific work) the former.

It appears therefore that an adequate collection of material cannotbe made in advance of any attempt to discuss its significance. Thesituation is familiar to natural scientists, and especially to historiansof science. The idea of beginning by compiling a natural history ofthe relevant material is chimerical, because what is and what is notrelevant can only be discovered in the course of investigation. Historyis not a science, and would-be historians who ignore this do so at theirperil, but it can be appropriate under some circumstances to imitatethe methods of the natural sciences and put forward a hypothesis.

II

Before one proposes a new hypothesis it is in general advisable toexplain why those hypotheses already in the field appear to be in-adequate. Of these two are particularly important: one is socio-logical (17), looking for an explanation in the social and economicchanges of the sixteenth and seventeenth centuries; the other isperhaps best described as pragmatic, in that it supposes that scientistsin the seventeenth century first made discoveries that could best be

(15) Christiaan HUYGENS, (Euvres com- Marxist thought is obvious, it does not seemplites (The Hague 1888-1950), vol. II, appropriate to classify as Marxist the type ofpp. 79, 115. explanation he offers. Analogous social

(16) La regola dell'accelerazione ne i explanations are sometimes widely acceptedgravi cadenti, Discorsi, in A. FAVARO (ed.), by non-Marxist historians—for exampleOpere di Galileo Galilei (Florence 1929- Zeller's explanation of the character ofI939)> vol. VIII, p. 374 (cf- P- 275). post-Aristotelian thought by reference to

(17) This is not, of course, to say that the changed political world after the rise ofall or even most sociologists would find it Macedon and the conquests of Alexander,plausible. Although Zilsel's debt to

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thought of as laws, and as a result came (almost by accident) to theidea of laws of nature.

i. The classic formulation of the sociological hypothesis was madeby Edgar Zilsel in his 1942 paper (18). His analysis is taken over, witha little additional material, by Needham in volume II of Science andCivilization in China (19), though Needham adds nothing to Zilsel'smain argument.

Zilsel's thesis is that the idea of applying legal concepts to natureis ultimately of Jewish origin (20). It lay dormant in the uncongenialclimate of the Middle Ages and revived with the development ofearly capitalism:

How could medieval theologians speak of the legislature of God, when the power ofthe prince was very limited ? The idea, however, had not originated in feudalism.It had been conceived under entirely different sociological conditions. Its authorswere Jews who had outgrown their past of Bedouin clan-organization centuriesago, and its sociological pattern was the despotism of ancient oriental states. Theidea could be preserved in a rudimentary form through two thousand years, eventhrough a period in which it did not fit the sociological conditions, till it awoke tonew life in early capitalistic absolutism (21).

What, one might reasonably ask, was it about early capitalism thatwas so propitious ? Zilsel provided two different and not obviouslycompatible answers. One is in terms of the activity of artisans:

We cannot explain here why at the time of Galileo the idea of mechanical regularitiesarose. This explanation exceeds our present task, since it is linked with the muchmore general problem of the origin of experimental science and the quantitativespirit, and will be attempted at another place. Here it may be indicated only thatin all civilizations experimentation originates in handicraft. In the period of nascentcapitalism experimenting artisans began to look for quantitative rules of operation.The roots of these mechanical rules, therefore, must be searched for in the socio-logical and technological conditions of handicraft in the early modern era. They roseto science in Galileo (22).

The other explanation is of a quite different character:

It is not a mere chance that the Cartesian idea of God, the legislator of the universe,developed forty years after Bodin's theory of sovereignty. Perhaps it is not even acoincidence that both thinkers were French: France was the native country ofcentralized absolutism. At any rate the doctrine of universal natural laws of divineorigin is possible only in a state with rational statute law and fully developed centralsovereignty (23).

(18) Edgar ZILSEL, The genesis of the ch. 18, esp. pp. 533-543.concept of physical law, Philosophical (20) ZILSEL, op. cit. pp. 247-249.Review, LI (1942), pp. 245-279. (21) Ibid. p. 279.

(19) J. NEEDHAM, Science and Civilisa- (22) Ibid. p. 276.tion in China (Cambridge 1954-), vol. II, (23) Ibid. pp. 278-279.

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Neither of these explanations seems plausible, (a) Highly skilledartisans and craftsmen have flourished in most civilizations. It isnot at all clear why the craft rules that had always existed should havetaken on a new significance in the sixteenth and seventeenth centuries.It is certainly not established that the activities of artisans had anyappreciable effect in bringing about the scientific revolution. Therelevance of craft-rules to the central discipline of astronomy isevidently minimal, and the prima facie rather more plausible case fora significant influence of practical gunnery on the other central disci-pline of dynamics evaporates on closer enquiry (24).

Even apart from these more general considerations, there is onefatal objection to the particular theses put forward by Zilsel. If itwere true that the modern idea of a law of nature has its roots in thetime when 'experimenting artisans began to look for quantitative rulesof operation' (25), then the first things to be called laws would be low-level generalisations derived from these craft rules. It is howeverclear from the evidence which Zilsel himself cites that the veryopposite was the case. As he rightly says (26), it was in Descartesthat the concept of a law of nature first occurs fully developed;and Descartes used it solely (27) for the fundamental laws of motion,which were not and indeed in the Cartesian system (in some cases)could not be reports of experience. The problem of arranging anyexperimental demonstration of Newton's first law is well known, butin the Cartesian system the same law has a positively counter/actualquality, insofar as the requirement that there should be no externalaction on the body is necessarily incapable of fulfilment if a vacuumis impossible.

When he was discussing empirical generalisations on the other hand,Descartes did not use any word meaning 'law'. We now think ofthe law of refraction: Descartes enquired instead for la raison ouproportion qui est entre ses angles (28). The same pattern of usage isfound in later writers in the century.

(b) The other explanation is more sophisticated: it could perhapsbe described as the pure Marxist explanation, in contrast with the

(24) A. R. HALL, Ballistics in the Seven- said that 'l'action de la lumiere suit en cecyteenth Century (Cambridge 1952), esp. les mesmes loix que le movement de cetepp. 36-56. bale'—the ball being a tennis ball projected

(25) ZILSEL, op. cit. p. 276. obliquely towards a surface. R. DES-(26) Ibid. p. 267. CARTES, CEuvres, edited C. ADAM and(27) Contrary to Zilsel's statement (p. 268 P. TANNERY (new edition: Paris 1965),

n. 83) Descartes did not describe the law Vol. VI, p. 100.of refraction as a law. In the place Zilsel (28) Ibid. p. 101.alleges (Dioptrique, ii) Descartes merely

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vulgar Marxist explanation just considered. It is more theoreticallysophisticated but its empirical basis in no more adequate. Absoluterule, unhampered by effective institutional constraints, is after allone of the most common of all kinds of government, and one that hasbeen experienced by much of the human race in forms far moreextreme than anything desired by Bodin or achieved by the Frenchmonarchy (29), without the concomitant appearance of any conceptof the world being governed by laws. Zilsel's rhetorical question,'How could medieval theologians speak of the legislature of God whenthe power of the prince was very limited ?' (30) can be very simplyanswered. They had no difficulty at all, and if Zilsel had read anymedieval authors other than Aquinas (31) he would have seen this.Elaborate discussions of the limits (if any) to the absolute power ofGod took place centuries before anything that can be described as anabsolute state began to exist in Western Europe; they are indeed oneof the most characteristic features of late medieval philosophy andtheology.

It is very misleading to imagine that in this period theologicalideas merely reflect political ideas, programmes or institutions.Very often the reverse is the case: ways of thinking first appear intheology and are only subsequently transposed to politics. In thelater Middle Ages some theologians had ascribed to God an absolutepower to choose moral laws, a doctrine which even Calvin describedas detestable (32). Only much later was a similar theory in politicsto appal the contemporaries of Hobbes.

2. The alternative, pragmatic, explanation is that the theoreticalacceptance of the notion of a law of nature resulted from its practicalemployment. On this view scientists began to think in terms oflaws of nature because they had discovered explanatory principleswhich could most appropriately be interpreted as laws (33). This

(29) K. WITTFOGEL, Oriental Despotism dropped this qualification and referred(New Haven 1957), passim. quite simply to irrational creatures obeying

(30) ZILSEL, op. cit. p. 279. laws, Of the Laws of Ecclesiastical Polity,(31) Zilsel did not read even Aquinas I. iii. 3-4.

carefully enough. He claims that 'the (32) The Institutes of the Christian Reli-metaphorical character of the term "law", gion, III. xxiii. 2.when applied to unreasonable beings was (33) This appears to be the thesis of Paolonot noticed before Suarez', op. cit. p. 279. Casini: ' Pour s*en tenir tout simplement aIn fact Aquinas explicitly said that the law la terminologie, on s'attendrait de voirin which irrational creatures participate apparaitre le mot " loi " en mSme tempsnon potest did lex nisi per similitudinem, que la chose : c'est-a-dire au moment ou lesSumma Theologiae, I* IIae, q.91 a.2 ad 3. cadres intellectuels de l'ancienne physiqueSuarez was following Aquinas, not making sont bouleverse's par le nouveau critere de laan innovation. What innovation there is quantity, par la ge'om&risation de l'imageis in the opposite direction, as when Hooker du monde. En r&lit^, la chose s'est imposee

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kind of explanation does have attractive features—not least becausesome of its analogues in neighbouring fields do appear to be right.It is at least plausible to think of modern scientific method as beingprimarily a creation of working scientists, something only subse-quently (and imperfectly) abstracted, articulated and developed byphilosophers of science. Certainly the much-trumpeted methodsannounced in the first half of the seventeenth century by Bacon andDescartes were at best only intermittently relevant to what scientistsactually needed to do.

This explanation has however to be rejected simply on historicalgrounds. Scientists and philosophers in the seventeenth centuryand even earlier referred quite freely to the laws of nature, even at atime when very few had been discovered and when those that hadbeen were not usually described as laws. Some examples may providean indication of this.

Galileo, to the best of my knowledge, never referred to any of thepropositions he had discovered in mechanics as laws—he spoke ofthem as theorems or propositions or rules. It is significant that the onlyreference to physical laws in all of Galileo's writings comes in aletter to his pupil Benedetto Castelli, the most important parts ofwhich were later incorporated almost without change in the morewell-known Letter to the Grand Duchess Christina, perhaps the nearestthing to a work of theology that Galileo ever wrote. In both lettershe described nature as 'the most observant executrix of the orders ofGod, obeying the laws (leggi) imposed on her' (34). The theologicalcontext and lack of scientific content of these phrases is significant.The idea of laws of nature was a theological inheritance quite foreignto the Archimedean paradigms Galileo followed in the formal exposi-tion of his mechanics.

Kepler also referred on a number of occasions to laws of nature (35),but he never used the word for what we now call Kepler's laws.

Descartes never described the sine law of refraction as a law,even though he did refer very frequently to laws of motion, bothvaguely and generally and in precisely specified terms, especiallyin Part II of the Principles of Philosophy (36).

More than anyone else, Descartes established and made respectable

avant le mot; l'usage du terme " loi " s'est 283, 316.generalise de facon curieusement tardive'. (35) J. KEPLER, Gesammelte Werke (Mu-P. CASINI, La loi naturelle : reflexion nich 1937-1975), vol. VII, p. 328. I owepolitique et sciences exactes, Studies on this reference to Casini (n. 36 above), whoVoltaire and the eighteenth century, CLI however wrongly attributes it to pp. 326-327.<i976), pp. 423-424. (36) The Principles of Philosophy, ii.

(34) GALILEO, Opere, vol. V, pp. 282- 37ft; Le Monde, ch. vii.

JOHN R. MILTON

the new terminolgy. Boyle used the word very frequently indeed inhis physico-theological writings (37). The exact content of theselaws of nature or laws of motion is usually left unspecified, thoughBoyle did occasionally refer to the Cartesian laws of inertia andimpact (38). The proposition which he never referred to as a lawwas what we now know as Boyle's law: this, with suitable modesty,he described as a hypothesis (39).

In fact it is not until Hooke that we find someone describingan empirically determined regularity of their own discovery as 'arule or law of nature' (40). By this time (De Potentia Restitutivawas published in 1678) the appropriateness of thinking in terms oflaws of motion was accepted by almost everyone, and the newterminology was beginning to be applied in other contexts than thatfor which it had first been devised.

This suggestion that scientists discovered laws of nature becausethey were already thinking of nature in law-like terms, and not theother way round, is further confirmed by the fact that talk of lawsof nature (in a physical, not a moral sense) was current among Euro-pean thinkers before the scientific discoveries of the seventeenthcentury had even begun to be made. Going back in time we findsome conception of physical laws of nature in Francis Bacon (41),Richard Hooker (42), Calvin (43) and Melanchthon (44). James 1,according to Bacon (for our purposes the correctness of the attributionis irrelevant) announced to his courtiers 'that kings ruled by thelaws, as God did by the laws of nature; and ought as rarely to put in

(37) The fullest treatment is in section (42) Of the Laws of Ecclesiastical Polity,vii of A Free Enquiry into the commonly I. iii.4.Received Notion of Nature, in Works (Lon- (43) The Institutes of the Christian Reli-don, 1772), vol. V, pp. 219-227. See also gion, I. xvi.5. Calvin on the whole avoidedvol. IV, pp. 161-164, vol. V, pp. 139-140, law terminology, even though he thoughtpp. 413-414 and pp. 520-521. of the world as a machine obeying the direct

(38) BOYLE, Works, vol. V, p. 399. commands of God; the reason appears to(39) Ibid. vol. I, p. 151. be that he thought of all God's commands(40) Robert HOOKE, De Potentia Resti- as special commands regulating particular

tutiva (London 1678), reproduced in fac- events. Every single year, month and daysimile in R. GUNTHER, Early Science in is regulated by a new and special providenceOxford (Oxford 1921-1945), vol. VIII, of God (I. xvi.2). The existence of excep-PP- 334> 336- tionless universal laws would suggest,

(41) Bacon's use of the word 'law' is contrary to Calvin's intentions, that God isnumerous and not obviously consistent. more interested in the broad outline ofThe most apparently modern uses are in what happens than in particular events.De Principiis atque Originibus, in J. SPED- (44) Francis OAKLEY, Christian theologyDING, R. L. ELLIS and D. D. HEATH (eds), and Newtonian science: the rise of theThe Works of Francis Bacon (London 1874), concept of the laws of nature, Churchvol. Ill, p. 115 (English translation, vol. V, History, XXX (1961), p. 455 n. 84. This isp. 496); and in Novum Organum, i. 75, an invaluable piece of research which deser-ii.2, ii.5, ii.17. ves to be better known than it apparently is.

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use their supreme prerogative, as God doth his power of workingmiracles' (45). James 1 was certainly in no position to state any ofthe laws of nature, but neither he nor his audience would have regardedthis as any reason to avoid such legal language.

Even in the Middle Ages, pace Zilsel, we can find similar ideas.There are references to laws ordained by God for the regulation ofnature in several later medieval authors, notably in Gabriel Biel (46),Jean Gerson (47), Pierre d'Ailly (48), Nicole Oresme (49) and Williamof Ockham (50)—and, further back into the thirteenth century, inRoger Bacon (51). A few isolated references might be brushed aside,but hardly a list such as this, incomplete as it certainly must be.Men were thinking of nature as governed by laws long before theywere in a position to state any of the laws themselves.

Ill

Laws of nature were not the first explanatory principles to bedevised for the purpose of understanding the phenomena of nature.The growing acceptance of the idea of a world governed by laws wasnecessarily accompanied by a rejection of the Aristotelian physicsof substantial forms and real qualities. It is therefore more appro-priate and useful to ask not simply how the idea of laws of naturearose, but rather how this new principle of explanation was ableto displace the old and well-established Aristotelian theory.

Historians and philosophers of science are now quite familiarwith the idea that theories are not abandoned as soon as they failto account for phenomena. Anomalies are clearly unwelcome andstrenuous attempts are usually made to remove them, but quite largenumbers can be tolerated if there appears to be no alternative todoing so. Broadly speaking, a theory will be discarded only whensome superior replacement becomes available. The changes thattake place in philosophy can be thought of in a similar manner, the

(45) Francis BACON, The Advancement n. 25.of Learning, Works, vol. Ill, p. 429. (48) OAKLEY, op. cit., p. 444 & n.

(46) G. B:EL, Collectorium super quattuor (49) Oresme uses 'ordenance' ratherlibros sententiarum, lib. I, d. 17 q. 1 art. 3, than 'loi'. Livre du Ciel et du Monde, ed.ed. W. WERBECK and U. HOFMANN (Tiibin- A. D. MENUT and A. J. DENOMY (Madisongen 1973-). vol. I, p. 419. I9<>8). P- 228.

(47) Quoted by H. OBERMAN, Reforma- (50) OCKHAM, Quodlibetae Septem (Stras-tion and revolution: Copernicus' discovery bourg 1491), VI. q.i.in an era of change, in J. E. MURDOCH and (51) There are numerous references inE. D. SYLLA (eds), The Cultural Context of Opus Maius, part. IV, dist. ii, 4.Medieval Learning (Dordrecht 1975), p. 425

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most important difference being that the problems associated withphilosophical positions are primarily internal and conceptual ratherthan external and empirical. There are two conditions which mustin general be fulfilled if a philosophical position is to be abandoned:severe internal difficulties, and the existence of some superior (orat least potentially superior) alternative. In the absence of the latterany well-developed philosophical outlook will usually retain its hold,despite a general acknowledgement of puzzles, obscurities and evenincoherences.

The requirements for the replacement of explanation in terms ofessences and substantial forms by explanations in terms of laws ofnature are therefore two: the first is a rejection of the realistic meta-physics on which both Aristotle's theory of demonstration and hisnatural philosophy are unmistakably (though somewhat obscurely)grounded; the second is a conception of the world which makes itpossible and indeed appropriate to speak of nature obeying laws,not just poetically or in daring metaphor, but in literal and prosaictruth.

These considerations suggest the hypothesis that the beginningsof the change in thought which led men to think of the physicalworld as being governed by laws can be found in the early fourteenthcentury. It was then that a series of thinkers, the first and greatestof whom was the English Franciscan, William of Ockham, developeda philosophy which included among its main elements both a completerejection of the metaphysical realism maintained by Aristotle and theearlier scholastics and an exceptionally strong emphasis on the absolutefreedom and omnipotence of God, especially in relation to the worksof creation (52). This school of thought has been given a numberof names, none of them entirely satisfactory. It has most often beendescribed, especially by historians, as the Nominalist movement.This name is perhaps the least unsatisfactory, but one caveat isnecessary. It is not only the nominalist element which is of historicalsignificance; the voluntarist emphasis on divine sovereignty is equallyimportant.

Nominalism has often been misunderstood in the past, perhapsbecause of the associations of the word itself. Properly conceived,nominalism has nothing to do with names. It is, quite precisely,

(52) The most detailed exposition of nately no full translation exists, but aOckham's nominalistic metaphysics is in critical edition of the Latin text can now bedistinction ii, questions 4-8 of the Ordinatio, found in his Opera Theologica (St. Bona-the first book of his commentary on the venture, N.Y., 1967-), vol. II, pp. 99-292.Sentences of Peter Lombard. Unfortu-

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the thesis that everything which exists is an individual, and is moreoveran individual in itself, and not merely as a result of any metaphysicalprocess by which something originally non-individual is made individ-ual through the agency of a principle of individuation. The dis-tinction between nominalists and realists is therefore quite sharp.Particular philosophers may be difficult to classify as nominalistsor realists, either because they are muddled, inconsistent, vague ordeliberately evasive, or else because they simply had no views on thequestion; nevertheless one cannot properly be a semi-nominalist,a moderate nominalist or an ultra-nominalist.

The metaphysics involved in the dispute between nominalistsand realists is certainly difficult and may well appear obscure—mostnominalists are indeed likely to deny that their opponents' positioncan even be coherently formulated. The consequences of nominalismon the other hand are clear enough. For a nominalist the worldcontains only individuals, and nothing else.

Voluntarism is less capable of precise definition. Its centralidea (here names are, for once, not misleading) is of things beingmade by some exercise of the will. Hence ethical voluntarism basesethics on moral rules chosen either by God or by human beings. Asfar as the physical world is concerned the only will that could be relevantis the will of God. The world was made either by God or by nobody,but in any case certainly not by us. In the present context, therefore,voluntarism may be thought of as the view that the world owes bothits existence and its nature to a free choice of God.

Some element of voluntarism is clearly a part of any theologywith even the most tenuous claims to Christian orthodoxy, althoughit is certainly possible for two people to put very different emphaseson a doctrine which they officially hold in common. In fact thecharacter of voluntarist theology becomes most clearly apparentwhen it is set beside the thought of a philosopher who rejected itcompletely. Spinoza held that the nature of everything necessarilyflows from God's nature in the very same way that theorems abouttriangles flow from the nature of a triangle (53), and therefore thatthings could not have been produced by God in any other manneror order than that in which they were produced (54).

This association with a voluntaristic theology explains the fact,noted earlier, that the word 'law' was originally used only in connectionwith the most fundamental processes of nature, and not with mere

(53) Ethics, book I, prop, xvii, note.(54) Ethics, book I, prop, xxxiii.

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regularities among phenomena. The memory of this reservation ofthe word 'law' survived long enough for J. Stuart Mill to record it:

The expression law of nature has generally been employed with a sort of tacit referenceto the original sense of the word 'law', namely the expression of the will of a superior.When therefore it appeared that any of the uniformities which were observed innature would result spontaneously from certain other uniformities, no separate act ofthe creative will being supposed necessary for the production of the derivative uni-formities, these have not usually been spoken of as laws of nature (55).

It was the combined impact of these nominalist and voluntaristcurrents of thought that slowly undermined the old Aristotelianphilosophy and prepared the way for the new idea of divinely imposedlaws of nature. These changes first began to be visible in the earlyfourteenth century. By then voluntaristic and nominalistic waysof thinking each possessed a long history.

Belief in a divine legislator for nature was not characteristic ofGreek thought. The gods and goddesses of the Homeric pantheon aresuperhuman rather than supernatural. They are themselves partof nature, as are the remote unconcerned deities postulated byEpicurus. Aristotle's God is supernatural if anything is, but he(or perhaps it—the personal pronoun hardly appears appropriate)is related to the world only as a final cause. The demiurge of theTimaeus is an efficient cause of a kind, but he does not induce orderin the world through the imposition of laws. The God of the Stoicsinterpenetrates and organizes everything like a wise, benevolent gas,but is neither transcendent nor a lawgiver. Cleanthes, it is true,did describe Zeus as the ruler of nature, governing all things by law (56),but here the context—the Hymn to Zeus—must be taken into account.The terms in which Zeus is conceived owe at least as much to ordinaryunphilosophical piety as to Stoic physics. Apart from this the nearestapproach in pagan Greek thought to the later conception of a divinelawgiver to nature is in the part-Aristotelian, part-Stoic De Mundo(written, it is thought, at some time between 40 B.C. and A.D. 140).Here the unknown author does (once) describe God as ruling theworld by means of laws (thesmois) (57). He also describes God asactually being a law (notnos) a few lines earlier (58). This lack ofprecision is an indication of the marginal character of the conceptin his thought. God is in any case not conceived as a transcendentcreator: he is literally situated at the circumference of the world and

(55) A System of Logic, IH.iv.i. Henceforth abbreviated to SVF.(56) H. von ARNIM, Stoicorum Veterum (57) [Aristotle], De Mundo, 4013/0.

Fragmenta (Leipzig 1903-24), I. 537. (58) Ibid. 4oobz8.

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manipulates it as a puppet-master manipulates his puppets, influenc-ing the more remote parts such as the earth only indirectly (59).

In Roman thought references to laws in connection with natureare slightly more common. In addition to the references in Lucretius,quoted earlier, there are others in Manilius (60) and in Ovid (61).The reason for these is not entirely clear. Roman law may havesome influence, but so would the greater detachment of these authorsespecially Ovid, from the mainstream of the Greek philosophicaltradition. The poetic character of all these references is in any caseapparent. None of them derives from any even remotely systematicphilosophy of nature.

The barrier which must inevitably prevent any systematic attemptto think of natural phenomena as governed by laws is the absence ofa belief in creation ex nihilo. If the world does not owe its wholeexistence to God, then no divine law can provide the fundamentalexplanation of the nature of things.

The idea of an utterly transcendent divine lawgiver creating theworld ex nihilo was, and was felt to be, an alien intrusion into Greekthought from outside, first from Judaism, later from Christianity.This idea was eventually to be of great importance in the emergenceof modern natural science, but initially it had surprisingly littleeffect even on the philosophy of those who accepted it. The writersof the Old Testament had no interest in (or indeed conception of)a science of nature of any kind, and their outlook was shared by thewriters of the New Testament and the earlier Church Fathers. Thefirst Greek author to speak with any frequency of laws of naturewas Philo Judaeus (62). Philo was concerned however more withmorality and religion than with the natural world; his attitude tothe latter owes much to contemporary Platonism, for which he isone of our main sources. The later Church Fathers also foundPlatonism the most congenial of the pagan philosophies, for thereasons summed up with admirable lucidity by Augustine in BookVIII of De Civitate Dei: the Platonists conceived of God as an imma-terial, self-existent being outside time and space, on whom the worldwholly depends but who is entirely independent of the world; andthey saw as the chief end of man the love and imitation of God.

Despite his Platonism, there are voluntaristic elements in Augus-

(59) Ibid. 398bi7-23. in Greek thought, in Jacob NEUSNER (ed.),(60) Astronomica, i.479. Religions in Antiquity: essays in memory of(61) Metamorphoses, xv. 71. Erwin Ramsdell Goodenough (Leyden 1968),(62) On Philo see Helmut KOESTER, pp. 530-540.

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tine's thought. (One of his statements, Creatoris voluntas rerumnecessitas est (63), could stand as an epigram for the entire movement).On the whole, however, these voluntaristic remarks and his occasionalreferences to laws of nature (64) occur in places where Augustinewas thinking primarily as a theologian, not as a philosopher. Thephilosophical world in which he moved was that of the Neoplatonists,and every kind of Platonism places the ultimate explanation of thingsnot in the will of a creator but in the intelligible relations of the Ideas,conceived by Augustine (as by all contemporary Platonists) to bethe thoughts of God.

This tension between a theology which emphasized the free-creative will of God and a philosophy in which explanations wereultimately grounded on the intrinsic necessity of the Ideas was neveradequately resolved by Augustine. Christian and Pagan alike wereturning away from the sensible to the intelligible world. The intellec-tual energy that would have been needed to create a new philosophyof nature had not vanished but was being employed elsewhere.John Philoponus tried, but even one remarkable man can effectlittle by himself against the intellectual current of his age.

Nominalism was very far from being unknown in the ancientworld. Indeed most of the Hellenistic philosophical schools (and theirimmediate precursors) explicitly or implicitly denied the existenceof universals. Antisthenes' worries about the possibility of definitionand predication, reported by Aristotle, can be most intelligiblyexplained by the supposition that he admitted the existence only ofindividuals (65), and the same philosophy is presumably the back-ground of his remark to Plato: 'I see the horse, but not the horse-ness' (66). A similar dictum is also attributed to Diogenes theCynic (67). Antisthenes' doubts about the possibility of predicationwere repeated by Stilpo of Megara, probably for the same reason (68).

There was also no room for universals in the materialistic physicsof the Stoics, and Zeno held that the Platonic Ideas should be thoughtof purely as mental images (69). Chrysippus and others attemptedto frame a semantic theory which would suppose the existence ofimmaterial lekta (literally, things said), but which would not require

(63) De Genesi ad Litteram, vi. 15. Fragmenta, edited F. D. CAIZZI (MilanQuoted by CALVIN, Insitutes, III. xxiii. 8. 1966)).A less epigrammatic version appears in De (67) DIOGENES LAERTIUS, The Lives ofCivitate Dei, xxi. 8. the Philosophers, vi. 53.

(64) De Civitate Dei, xv.12, xxi.8 (twice). (68) PLUTARCH, Adversus Colotem, 1119C-(65) Metaphysics, 102^132-34, 1043025- 1120B.

28; Topics, 104D2/. (69) SVF, I.65, 494.(66) ANTISTHENES, Fr. 50 (Antisthenis

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reference to any entities in the world other than purely materialindividuals. This lekton theory, whatever its merits or demerits, isirrelevant to the study of nature. One of the cardinal principlesof Stoic physics is that only bodies are capable of acting or beingacted upon (70).

Epicurus must also be classified as a nominalist. He was notinclined by temperament to discuss the views of his predecessors, andthose letters and fragments which have come down to us contain noexplicit discussion of the universals of Plato and Aristotle. Never-theless it is quite clear that there is no place for universals in a systemin which only atoms and the void in which they move are allowedto exist.

Most of the Hellenistic schools of philosophy therefore rejectedthe realistic metaphysics underlying the Aristotelian theory of demon-stration and the related conceptions of form and essence. Neverthelessthe idea of a natural science directed towards discovering laws ofnature did not arise to take its place, as it did when Aristotelianphilosophy was again discarded in the seventeenth century. Onereason for this is that none of these Hellenistic schools was interestedin research for its own sake, as Aristotle had been and as his successorsin the Lyceum (notably Strato) still were. Needham's descriptionof the Epicureans as the most scientific of all the schools of anti-quity (71) could scarcely be more mistaken. Epicurus' systemwas naturalistic, not scientific. His approach was wholly and inten-sely dogmatic, and this dogmatism, coupled with a lack of desireto advance beyond the Founder, remained a uniform characteristicof the school (72). The study of nature was undertaken by Epicurusin order to provide a defence against the myths and bogies of traditionalreligion; it was neither disinterested research nor (as for most scientistsin the seventeenth century) an exploration of the works of God.

In the mechanical philosophy of the seventeenth century thereare two distinct levels of explanation: the (internal) structure ofbodies and the laws of motion (and, after Newton, of forces also).The ancient atomists also aimed at explaining the macroscopicproperties of bodies in terms of the arrangement of their componentatoms. It can therefore seem to us quite a small step to move on toenquiring after the laws governing the motions of these parts. SinceDescartes it seems natural to pay particular attention to collision

(70) SVF, I.90, II.387. was called the Leader (hSgemon), J. M.(71) NEEDHAM, op. cit. p. 536. RIST, Epicurus: an introduction (Cambridge(72) Epicurus's followers took an oath to 1972), p. 9.

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JOHN R. MILTON

phenomena and to ask what law connects the velocities of the collidingbodies before and after impact. It would be a mistake to supposethat the step would have been small in Antiquity. Epicurus wasquite uninterested in a quantitative discussion of physical problems,and in this instance he lacked the concept of inertial motion necessaryif the problem is even to be clearly stated. Moreover nothing wouldhave led Epicurus to admit divine government of the world, andany physical concept which even involved a hint of such governmentwould have been left unused, whatever its potential usefulness inresearch.

In contrast to the Epicureans, the Stoics felt no hostility towardsthe idea of divine providence—indeed quite the contrary. Godwas not however conceived as a transcendent creator ruling by law,but rather as an all-pervading material pneuma. The world as awhole is animate and even intelligent because of this divine elementpervading every part of it. This active divine element is related tothe passive matter of the world in the way that the human soul isrelated to the body, and it no more controls the world by laws thanwe do our bodies (73). The Stoics had a profound influence, throughCicero, on the juridical idea of Natural Law but very little on the ideaof physical laws of nature.

The Stoics, the Epicureans and the other nominalist schoolsgradually lost ground in the first few centuries of the Christian era,first to the Middle Platonists, then to the Neoplatonism of Plotinusand his successors. The voluntaristic element in Christianity waspushed to some extent into the background by the Platonic modesof thought current among the more philosophically sophisticated ofthe Church Fathers. Nominalism reappeared in the West with therevival of philosophy in the late eleventh and early twelfth century,but the philosophers involved were concerned with logic and seman-tics, not with natural philosophy. The subsequent reception ofalmost the entire body of Aristotle's writings made these earlierenquiries appear narrow and inadequate; they were largely forgotten,just as the later medieval writers were to be forgotten in their turn.It was not until the beginning of the fourteenth century that nominalisttheories were again revived and combined with a thoroughly volun-tarist interpretation of Christian theology. The synthesis of thesetwo streams of thought helped to create a philosophy of naturewhich was to be characteristic not only of Ockham and his medievalsuccessors, and of Calvin and others among the sixteenth-century

(73) CICERO, De Natura Deorum, ii. 23-39; DIOGENES LAERTIUS, The Lives of thePhilosophers, vii. 134-157.

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Reformers, but also of many of the scientists and philosophers ofthe seventeenth century. This is especially the case in England,where Bacon, Hobbes, Boyle, Locke and Newton (74) all show clearsigns of the influence of nominalist or voluntarist ideas; it is alsothe case in France, where similar influences strongly affected thethought of Descartes (75), Gassendi (76) and Mersenne (77).

Since the time of Duhem much work has been done on the scienceof the fourteenth century and its connection (or lack of connection)with the new inertial mechanics of Galileo and his successors. Thephilosophical innovations of the fourteenth century did influencethe natural science of the period, and hence perhaps indirectly thescience of the seventeenth century; nevertheless the major influenceof Ockham and his successors was less on the content of the scientificideas themselves than on the new metaphysics and philosophy ofnature which they began and which was further developed by theadvocates of the new mechanical philosophy. It was this philosophyof nature that provided a context within which the idea of a law ofnature was both comprehensible and natural. Its main elements areas follows:

/. There exists a very sharp and infinitely wide distinction betweenGod and the created world. There is nothing divine about eitherthe world as a whole or any part of it; divinity can be ascribed solelyto its maker.

This conception of the relation of God to the world is fundamen-tally in opposition both to any Neoplatonizing account of the originof the material world by emanation from the divine substance, andto any Stoic or Platonic picture of the world as the body of a divineanimal, of which God is the soul. Newton vigorously expressedhis rejection of this unworthy conception of God:

This being governs all things, not as the soul of the world, but as Lord over all; andon account of his dominion he is wont to be called Lord God pantokrator or Universal

(74) The influence of Henry More's and activate it'. The changing World oftheory of space should not mislead anyone the Newtonian Industry, Journal for theinto considering Newton as a Platonist. History of Ideas, XXXVII (1976), p. 179.The following verdict by R. S. Westfall (75) Descartes's extreme voluntarism ap-appears to me to be entirely accurate. pears most clearly in his correspondence,'Try as I may, I am unable to perceive a see especially the letters to Mersenne,neoplatonic hierarchy in the natural philo- 15 April 1630, 6 May 1630, 27 May 1630sophy of the mature Newton. I perceive and to Mesland a May 1644.instead a sharply dichotomized universe (76) Olivier BLOCH, La philosophie dewith God Pantocrator, on the one hand, Gassendi (The Hague 1971), Chs. iv, v.and on the other, inert matter which is (77) R. LENOBLE, Mersenne ou la nais-moved and activated only insofar as the sance du mtcanisme (Paris 1943), esp.omnipresent God acts immediately to move pp. 275-279, 321, 325.

JOHN R. MILTON

Ruler; for God is a relative word, and has a respect to servants; and Deity is thedominion of God not over his own body, as those imagine who fancy God to be thesoul of the world, but over servants (78).

2. Everything which exists (and to which appeal in explanationcan therefore legitimately be made) is an individual. Although wemay continue to speak of forms, nevertheless in nature, accordingto Francis Bacon, nothing exists except individual bodies actingaccording to laws (79). In Boyle's words,

For, for aught I can clearly discern, whatsoever is performed in the merely materialworld, is really done by particular bodies acting according to the laws of motion,rest, etc., that are settled and maintained by God among things corporeal [...] (80).

3. The omnipotence of God, always an element of orthodoxChristian theology, is given particular emphasis. Appeal was freelymade to this doctrine (regarded, in general, as a truth of naturaltheology), not only by scholastic theologians but also by relativelyuntheologically-minded philosophers. Descartes's main argumentagainst the existence of atoms relies wholly on the unlimited powerof God: God could unquestionably make a particle too small forany creature to subdivide, but he could not deprive himself of thepower of sub-dividing it further (81).

In discussing the power of God the medieval nominalists made useof a distinction between his potentia absoluta and his potentia ordi-nata (82). The meaning of these terms is largely self-explanatory.Anything that God can do at all lies within his absolute power;something lies within his ordained power if it can be done withoutbreaking the laws he has freely chosen to establish. God's absolutepower is not quite unlimited: he cannot sin or die (83), or makeanother God (84). Nevertheless with respect to his creation it iscomplete: God can suspend the causal powers of created things (85),give them unnatural properties (for example by making fire cold (86),and in general make any one real thing exist in the absence of anyother (87).

(78) Isaac NEWTON, The Mathematical of it.Principles of Natural Philosophy, trans. (83) OCKHAM, Ordinatio, d.42 q.i, OperaA. Motte, rev. F. Cajori (Berkeley i960), Theologica, vol. IV, p. 610.p. 455. (84) OCKHAM, Ordinatio, d.20 q.i, Opera

(79) Novum Organum, ii. 2. Theologica, vol. IV, p. 36.(80) BOYLE, Works, vol. V, p. 218. (85) OCKHAM, Ordinatio, prologue q.8,(81) The Principles of Philosophy, ii. 20. Opera Theologica, vol. I, p. 221.(82) This distinction can be found in (86) OCKHAM, Ordinatio, d.i q. 3, Opera

earlier writers (e.g. Aquinas, Summa Theolo- Theologica, vol. I, p. 423.giae, I* q.25 a.sadi); Ockham was however (87) OCKHAM, Ordinatio, prologue q.i,the first philosopher to make extensive use Opera Theologica vol. I, p. 38.

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A very similar account of God's power can be found in Boyle.The only limits to God's power are in connection with his own natureand with what is logically impossible. 'There are some notionsor propositions, that are therefore impossible to be true, becausethey are repugnant. I say, not to the changes of the textures, orother modifications of things, but to their essential ideas, if so I maycall them' (88). God was entirely free in his choice of the lawsof nature and 'by with-holding his concourse, or changing theselaws of motion, which depend perfectly upon his will, he may invalidatemost, if not all the axioms of natural philosophy' (89).

4. God governs the world, not by means of intermediaries of anykind, but directly, by regulating the motion of every single body,however tiny and unimportant. In physics, God not only gives animpulse to matter at the beginning but also conserves this impulseby means of exactly the same action as that which first created it (90).Indeed, according to Descartes the difference between creation andconservation is nothing more than a difference of reason, made byour minds but not found in reality (91).

Because God acts directly on matter everywhere, all the inter-mediaries proposed by the various schools of Greek philosophy andabsorbed into the world-picture of the Middle Ages and Renaissanceare to be discarded without exception. As Boyle put it, one mustnever think of God and Nature as two co-ordinate governors, likethe two Roman consuls (92). The idea of Nature as a natura naturansor semi-deity needs to be rejected completely as encroaching on thesovereignty of God (93).

5. The distinctions between natural and artificial bodies andbetween natural and violent motion, both quite central in Aristotle'snatural philosophy, lose their importance. The fundamental anti-thesis in Christian theology is not between violence and nature orart and nature, but between grace and nature. Miracles are allowedto be contrary to the laws of nature, but such exercises of God'sabsolute power are restricted to the order of grace. All movementswhich occur in the ordinary running of the world, whatever theircharacter and direction, are fully natural because they take place inaccordance with the laws of nature. The idea that there exists afundamental difference between natural and artificial bodies, an ideacentral to Aristotle's philosophy, is therefore abandoned. The

(88) BOYLE, Works, vol. VI, p. 677. (91) Meditations, iii, (Euvres, Vol. VII,(89) BOYLE, Works, vol. IV, p. 161. p. 49.(90) DESCARTES, The Principles of Philo- (92) BOYLE, Works, vol. V, p. 185.

sophy, ii.36, 4Z. (93) Ibid. pp. 167, 169.

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modern distinction between natural and synthetic substances is adistinction of origin, not of nature. The older distinction could notbe retained in a world in which all things were at the same time arti-ficial, because they had been made by God, and natural, becausethey were governed by the laws of nature. In the middle of theseventeenth century, Sir Thomas Browne could savour a view thatwas becoming the new orthodoxy, but which still retained an air ofparadox: 'All things are artificial, for Nature is the Art of God' (94).

6. Finally, and in some ways most importantly of all, there isa belief in the radical contingency of the world, and hence of thelaws of nature also. Outside astronomy the most remarkable achieve-ments of the Greeks in the physical sciences had been in disciplinessuch as statics and hydrostatics, in which apparently self-evidentand necessary axioms could be found which would serve as premisesfor subsequent deduction. To think of such axioms as laws wouldhave been quite unnatural, and no-one did so. A 'science' whosefirst premises were not self-evident and incapable of proof would not,for Aristotle, have been a science at all (95). Laws of nature freelyestablished by God could not have this necessary character. Ourworld is only one of many possible; its laws are contingent and canbe discovered, not by reasoning but only by experimental enquiry.Newton's disciple Roger Cotes was guided by this tradition when hemade his severe judgement on those who, like Leibniz, supposedthat they could discover a priori the laws of nature:

Without all doubt this world, so diversified with that variety of forms and motionswe find in it, could arise from nothing but the perfectly free will of God directing andpresiding over all.

From this fountain it is that those laws, which we call the laws of Nature, haveflowed, in which there appear many traces indeed of the most wise contrivance, butnot the least shadow of necessity. These therefore we must not seek from uncertainconjectures, but learn them from observations and experiments. He who is pre-sumptuous enough to think that he can find the true principles of physics and thelaws of natural things by the force alone of his own mind, and the internal light ofhis reason, must either suppose that the world exists by necessity, and by the samenecessity follows the laws proposed; or if the order of Nature was established bythe will of God, that himself, a miserable reptile, can tell what was fittest to bedone (96).

It is perhaps the acknowledged contingency of its ultimate principleswhich, more than anything else, separates the science of Newtonfrom the science of Archimedes.

(94) Sir Thomas BROWNE, Religio Medici, (96) Roger COTES, Preface to the 2nd edi-j.16. tion of Newton's Principia, trans. A. Motte,

(95) Posterior Analytics, 7465-13, 83D32- rev. F. Cajori (Berkeley 1960), p. xxxii.8436.

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IV

Once the idea of laws of nature had become generally accepted, itwas possible (for those who so wished) to reject the theological stand-point which had originally made the idea acceptable. The attemptto do this began quite early: already in the 1680s Boyle found itnecessary to argue that it is only possible for a world to be governedby laws if God is constantly active within it (97). Inanimate bodiescannot understand laws and hence cannot by themselves follow them.Bodies can move and transfer their motion to other bodies only becauseGod continuously guides and regulates their movements. A law-governed world superintended by God is possible, as is a chaos; alaw-governed world in which God does not act (either because hedoes not exist or for some other reason) cannot coherently be sup-posed to exist.

Boyle's works continued to be widely read in the century after hisdeath, but this particular argument failed to secure any generalacceptance. The same was true of the similar though more complexand ambitious arguments put forward by Malebranche and by Ber-keley. By the middle of the eighteenth century, if not before, theconcept of a physical law of nature had become one of those most basicof all concepts, which apparently require no metaphysical justificationfor their use and which are therefore employed with complete confi-dence. The idea of laws of nature could now appear to be natural;the slow changes of thought that had led to its genesis could beforgotten.

(97) A Free Inquiry into the Commonly received Notion of Nature, section ii, Works,vol. V, esp. p. 170.

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milton - origin and development of concept laws of nature 1981

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