the composition of economic causes - daniel hausman
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The Composition of Economic CausesAuthor(s): Daniel M. HausmanReviewed work(s):Source: The Monist, Vol. 78, No. 3, The Metaphysics of Economics (JULY 1995), pp. 295-307Published by: Hegeler InstituteStable URL: http://www.jstor.org/stable/27903438 .Accessed: 22/06/2012 09:32
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The Composition of Economic Causes*
Although John Stuart Mill is an empiricist and an inductivist, he believes that inductive methods are not directly applicable to most subject matters. He believes that his methods of induction are suitable only to
domains in which few causal factors are at work, and most subject matters
are complex and involve the simultaneous action of many causal factors.
The possibilities of experimental intervention increase the range of direct
inductive inquiry, but that range is still limited.
Mill believes that scientific knowledge of complex subject matters
can be attained by deducing from inductively attained knowledge of the
action of single causes what the consequences of multiple causes acting
simultaneously will be. Mill calls this procedure "the deductive method" or "the method a priori" but both names are misleading. The deductive
method is, in fact, an indirect inductive method, in which the laws of in
dividual causes are separately determined by inductive methods. The role
of deduction is to determine what follows from these laws in complex cir
cumstances. The evidence that inductively supports the premises of a
deductive argument is supposed to be the inductive basis for one's belief
in the argument's conclusions.1 In Mill's words:
When an effect depends on a concurrence of causes, these causes must be studied one at a time, and their laws separately investigated, if we wish, through the causes, to obtain the power of either predicting or controlling the effect; since the law of the effect is compounded of the laws of all the causes which determine it. {Logic, 6.9.3)
If one wants to "obtain the power of predicting or controlling" an effect
such as projectile motion through understanding its causes, one needs to
investigate separately the separate causal factors (gravity, momentum,
friction) and their laws.
This notion of "compounding of the laws of all the causes," of de
ducing the consequences of the concurrence of a plurality of causes, is
"The Composition of Economic Causes" by Daniel M. Hausman, The Monist, vol. 78, no. 3, pp. 295-307. Copyright? 1995, THE MONIST, La Salle, Illinois 61301.
296 DANIEL M. HAUSMAN
problematic. Mill takes explanations in dynamics as paradigmatic and
does not pause over the notion of adding up the effects of different causes.
But the notion of "compounding" is not simple or straightforward even in
the case of classical mechanics. I shall disentangle some of the principles Mill invokes in attempting to explain how scientific knowledge of
complex subject matters is possible, and I shall argue that his account
fails. Some of the problems in acquiring knowledge of complex subject matters arise from details of Mill's philosophy of science, but some
remain for non-Millians to grapple with, too.
As Mill recognized, one can find regularities in complicated
phenomena. But these regularities, which Mill called "empirical laws," are not explanatory, and they are a precarious basis for prediction. Until
empirical laws are linked to underlying causal laws, one does not know
when the empirical laws can be relied upon and when they are likely to
break down. Empirical laws are nevertheless a valuable part of science, because they constitute data which theories should explain and because,
despite their precariousness, they may be of use. Scientists should not,
however, rest content with empirical laws. They should seek to uncover causal laws, and they cannot succeed in doing so by applying direct
inductive methods to complex subject matters. When in this paper I shall
speak of "laws," I shall be referring to causal laws.
Social phenomena are particularly inappropriate candidates for the method of "specific experience" or "the method a posteriori" because
they are complex, available in limited varieties, and not subject to appre ciable experimental manipulation. If Mill were a physicist, he might stop there with expressions of pity for the plight of the social theorist. But social phenomena and especially economics are Mill's main interest, and
he wants to explain how one can acquire scientific knowledge of them.
The explanation lies in Mill's direct deductive method.2 This method is not applicable to the general science of society, because there are too
many causes for us ever to ascertain all their laws and to determine their
combined effects, but it will work in subject matters such as economics in
which, in Mill's opinion, there are few really significant causes.
When Mill first introduces the deductive method in Book III of A
System of Logic, he envisions scientists deriving the laws governing
complex phenomena from the laws of all the relevant causes. Suppose, for
example, Wilson is sick, and we would like to know whether penicillin
THE COMPOSITION OF ECONOMIC CAUSES 297
will help cure Wilson.3 The method a posteriori would have us inquire whether others with symptoms resembling Wilson's recovered more often or more rapidly when given penicillin. The method a priori in contrast
would have us draw upon our knowledge of the causes of Wilson's
symptoms and upon our knowledge of the operation of penicillin to decide
whether penicillin will help cure Wilson. Both methods are "empirical" and involve testing. The difference is that the former attempts to use ex
periment or observation to learn about the complex phenomenon directly, while the latter employs observation to study the relevant component causal factors.
In an example such as this one, the deductive method seems unob
jectionable, but in economics, causal factors that are known to be
significant are left out of the story. As Mill was well aware, economic
agents may be motivated by all sorts of passions?whether they be
patriotic, malevolent, benevolent, or neurotic?which are left out of
economics. Mill seems to be of two minds about whether this is scientifi
cally acceptable. On the one hand, he criticizes members of the "school of
Bentham" (including his father, James Mill) for theorizing about govern ment without incorporating all the causes, whether significant or not
{Logic, 6.8.3). But when it comes to economics, Mill apparently recom
mends just the methodological practice that he condemns in his father. For the correct method of including all the causes "within the pale of the science" is not feasible. Economists must set their sights lower and aim
only at a hypothetical science of tendencies which is, in Mill's view,
generally "insufficient for prediction" yet "most valuable for guidance"
{Logic, 6.9.2). Let us call this sort of deductive method, that so closely resembles
the method of Mill's father, "the inexact deductive method," because it in
corporates only some of the causes. J. S. Mill defends this method as
follows:
The motive which suggests the separation of this portion of the social
phenomena from the rest, and the creation of a distinct branch of science
relating to them, is, that they do mainly depend, at least in the first resort, on one class of circumstances only; and that even when other circumstances interfere, the ascertainment of the effect due to the one class of circumstances alone is a sufficiently intricate and difficult business to make it expedient to
perform it once for all, and then allow for the effect of the modifying cir
298 DANIEL M. HAUSMAN
cumstances; especially as certain fixed combinations of the former are apt to recur often, in conjunction with ever-varying circumstances of the latter class. (Logic, 6.9.3)
The defenses Mill offers here for employing this inexact deductive
method seem to be (1) practical?there is no alternative, (2) metaphysi
cal?although the results are only hypothetical, the tendencies persist even when there are other disturbing causes, and (3) pragmatic?this is an
efficient way of theorizing, and more order can be found this way than in
any other.4 I shall be questioning these defenses.
In the case of economics, theorists following the deductive method
first borrow basic "laws" from the natural sciences or from psychology, which Mill regards as an introspective experimental science. Then
theorists deduce what follows from them in various circumstances.
Finally, verification is essential (though not in order to test the basic laws, which are already established and could hardly be cast in doubt by the
empirical vicissitudes of a conclusion deduced from a partial set of
causes). It is unclear whether verification is necessary in order to regard the deductively derived laws as economic laws at all, or whether verifica tion merely determines the applicability of these laws.5
Applying the deductive method in economics is much messier than
the discussion so far suggests. The laws that one derives are inexact and sometimes drastically in conflict with the phenomena. This inexactness is
only to be expected, since many causal factors are left out of the deriva tion. But the problems lie deeper, because the premises in the deductions are not established laws or true descriptions of the relevant circumstances.
The non-law premises are frequently extreme simplifications, such as
claims that commodities are infinitely divisible or that knowledge is perfect. The evidential weight of a deductive derivation of a causal law for a complex system would, it would seem, depend on whether such simpli fications are dispensable or in some sense reasonable approximations.
A more serious difficulty concerning the deductive method involves the supposed "laws" of the component causes, since it is questionable, at
least in the case of political economy, whether they are really laws. For
example, Mill believes that the most basic law of political economy is that
people seek more wealth, yet he asserts that it is absurd to maintain that
people do in fact always seek more wealth (Logic, 6.9.3)! What's going on?
THE COMPOSITION OF ECONOMIC CAUSES 299
A simple example from physics may be helpful here. Suppose that a
ball-bearing is falling straight down through a column of water, and
suppose that it is subject to only two forces. There is a downward force of
gravity, mg, which is constant, and an upward force of resistance that
depends on several factors and varies with the speed of the ball. These two
forces are the two component causes. Galileo's law describes the
operation of one of these component causes, and hydraulics provides the
law of the other. If Galileo's law is formulated as the claim, "All bodies near the surface of the earth fall toward the center of the earth with a
constant acceleration," it is, of course, just as false as is the claim that
people always seek more wealth. Galileo's law is instead usually under
stood as making a qualified or modal claim: in the absence of any other
forces, bodies (would) fall with a constant acceleration. Similarly one
might interpret the claim that people seek more wealth as maintaining that
in the absence of any other causes (or ceteris paribus), people seek more
wealth.6
Read this way, Galileo's law tells us what happens in the absence of
the resistance, and the laws of fluid mechanics tell us what happens in the
absence of forces such as gravity. Newton's first law tells us what happens when both causes are absent. That leaves only the problem that we started with: What happens when both causes are present? How are the laws of the component causes supposed to tell us this? How are we supposed to
"compound the laws"? No amount of knowledge of the separate component causes is going to tell us what will happen when they act
together. We need to know something extra about their joint action.
Suppose that this something extra is that the net force is the vector sum of the component forces. If the forces are described as above in for
mulations that state how things would be if the forces were acting alone, then there is no way to "compound the laws." To make sense of the notion
of adding component forces, we thus need to reformulate the laws of the
component causes. We should replace Galileo's law with the claim (GO that the net force on the ball is larger by mg in the downwards direction than if gravity is not present. (C) should not, however, be identified with Galileo's law, for, unlike Galileo's law, (G') is true only if forces are
additive. If forces were not additive, (G') would be false, even if Galileo's law were true.7
At any instant, then, the net force downwards will be mg minus the
force of resistance, though calculating the rate at which the downward ac
300 DANIEL M. HAUSMAN
celeration diminishes and what terminal velocity the ball reaches requires much more than simple arithmetic. To make possible the "deduction" of
the net force, one needs to know more than just how the causes act sepa
rately?one needs to know the law governing their combination, and this
law cannot be derived merely from knowledge of how they act separate
ly. To speak, as Mill does, of a deductive method, is misleading because
the law governing the conjoint operation of causes cannot be deduced
from the laws governing the component causes separately. Given the additivity of forces, it is natural to describe the component
causes as giving rise to "tendencies." This is the interpretation of Mill
defended by Nancy Cartwright.8 On this interpretation, claims such as
"People seek more wealth" express "tendencies" or "capacities" rather
than laws. Such tendencies give rise to regularities such as Galileo's law
and G', and it is by virtue of the connections between tendencies and reg ularities that claims about tendencies can be tested. The tendencies are not
however themselves equivalent to regularities. For example, people's
tendency to seek more wealth might give rise to nearly universal wealth
seeking behavior in circumstances such as those that characterize stock markets. But the claim that people tend to seek more wealth is not
reducible to any of the regularities to which it gives rise. For the tendency claim is not restricted in scope, and the tendency is supposed to remain
"operative" even when it is not reflected in any known regularity. I am not sure whether one understands methodology and explanation
better if one focuses on laws or if one focuses on tendencies or even
whether it turns out to matter. Talk of tendencies or capacities has little
point unless tendencies persist and can be added, balanced, weighed, or
otherwise combined. Talk of tendencies is only useful when we have in
mind some principles (such as additivity in the example above), which describe the ways in which tendencies manifest themselves in different
circumstances. Once we have such principles, we can, however, focus on
generalizations (such as G' above). I do not think that Mill's writings clearly commit him to either a tendency or a ceteris-paribus law view of
component causes, and indeed I do not think that Mill distinguished
clearly between these interpretations of "laws" of component causes. I
tentatively prefer the ceteris-paribus law view of component causes, because it seems to me the most modest metaphysically and because I'm
leery of taking the revolutionary step of demoting laws from their central
THE COMPOSITION OF ECONOMIC CAUSES 301
role in the understanding of science. But the decision ultimately depends on what theories of scientific explanation and theory construction are most
satisfactory. At a superficial level both accounts appear to be capable of
explaining how people's pursuit of more wealth can be a fundamental
cause, even though there is no universal law saying that people seek more
wealth. Both interpretations also permit one to describe the difficulties
that arise in "compounding" causes. So without resolving this metaphys ical conundrum, let me expand upon these difficulties.
One serious problem for the deductive method is, as we have seen, that it is not possible to deduce what happens when causes act jointly from
knowledge of what happens when they act singly. How could Mill have
thought otherwise? In Book 3 of his Logic Mill writes:
Now, if we happen to know what would be the effect of each cause when
acting separately from the other, we are often able to arrive deductively, or a
priori, at a correct prediction of what will arise from their conjunct agency. To render this possible, it is only necessary that the same law which
expresses the effect of each cause acting by itself shall also correctly express the part due to that cause of the effect which follows from the two together. This condition is realised in the extensive and important class of phenomena, commonly called mechanical, namely, the phenomena of the communication of motion (or of pressure, which is the tendency to motion) from one body to another.. In this important class of cases of causation, one cause never, properly speaking, defeats or frustrates another; both have their full effect .... This law of nature is called, in dynamics, the principle of the Composi tion of Forces: and, an imitation of that well-chosen expression, I shall give the name of the Composition of Causes to the principle which is exemplified in all cases in which the joint effect of several causes is identical with the sum of their separate effects. (Logic, 3.6.1)
Mill is claiming that one can deduce what will happen when causes are
combined from the laws of their separate action plus the principle of the
Composition of Causes, which says that "the joint effect of several causes
is identical with the sum of their separate effects." I shall call this
principle, "the additivity assumption." In mechanical phenomena like the
falling ball-bearing, one "adds up" the forces (or the accelerations they cause) and gets the right answer. It would be more informative to call the method Mill is espousing "compositional" rather than "deductive" for the
derivation of the combined effect is a process of adding and subtracting. If one assumes additivity, then the deductive method can work, but
we're not yet out of the woods, for it is not clear what additivity means
302 DANIEL M. HAUSMAN
outside of the special case of mechanics. In some instances one can take
it literally as, for example, when one interprets a change in quantity demanded as a sum of an income and a substitution effect.9 But how is one
supposed to "add up" the consequences for behavior of, for example, un
certainty, time preference, diminishing marginal rates of substitution and
diminishing returns? What goes on in much of economics is more like
deducing than adding, and it is unlike what Mill envisioned. Even if one could make clear what was involved in "adding" causal
factors in economics, it is hard to see what justification there might be for
assuming that the causes for some particular set of phenomena are in some
sense additive. In the case of the ball-bearing, it seems to be easy to
defend the assumption that the causes are additive. One can alter the
viscosity of the liquid within which the ball is falling and even, at great expense, alter the gravitational force. The predictions of the combined
formula are in good agreement with the data. But the same possibilities of
experimentation that show us that we have got the combined law right also make the deductive method unnecessary: Mill's methods of induction can be applied directly to the combined law. Proceeding by studying the component causes separately might of course have many advantages, but
it is not needed in order to justify the claim that the formula combining
gravitational and frictional forces is indeed a causal law.
What justifies the compositional assumption when one cannot
directly establish the combined law? The effect of multiple causal factors
acting together might be completely different from the "sum" of their
separate effects. Causal factors may interact, and Mill has provided little reason to believe that tendencies, such as the tendency to seek more
wealth, are still "acting" in the presence of other causes. One might think
that one could answer this skepticism about the possibility of developing economics deductively merely by successfully carrying out the steps of the deductive method. And I think that in fact Mill is confident of the pos sibility of developing economics deductively because of how neatly his and Ricardo's economics follows from simple and plausible premises. For
example, given the capitalist's drive for profits, the worker's inclination to
breed, and diminishing returns in agriculture, Ricardo and Mill held that rates of profit should decline and population and rents should increase.
But the classic argument for diminishing rates of profits and increasing
population and rents is not aptly described as a procedure of adding
THE COMPOSITION OF ECONOMIC CAUSES 303
component causes, because none of the three factors violate any of the
ceteris paribus conditions attached to the other factors. For example, di
minishing returns is not a force that needs to be added or subtracted from
the drive to maximize profits, and the latter does not need to be added to
or subtracted from the propensity to propagate. One thus needs no addi
tivity assumption to derive the economic conclusion concerning profits and rents, and so the success (such as it was) of an economics based on
such a derivation does not support the additivity assumption.10 Furthermore, even if Mill's economics followed his compositional
method or the more straightforward deductive method much of economics
actually follows, its apparent success would not vindicate the method.
Suppose that the derivation of diminishing rates of profit and increasing rents did exemplify Mill's deductive method and suppose (contrary to
19th-century data), one found that the rate of profit did diminish and rents
and population did increase. Would one then be justified in regarding this
trend as a causal law? The demands of the deductive method would have
been met, but what reason is there to believe that the factors mentioned cause the diminishing rates of profit and increasing rents? Empirical studies only establish the existence of an empirical law. To believe that one has a causal law, one has to believe that the deduction correctly
displays how the individual causes act together. But this is what needs
showing. Mill has no answer for those who doubt whether causal laws of
complex phenomena such as economies can be deduced from the laws of the separate causes.
If the derivation of economic laws were a matter of strict logical deduction from a set of true premises, these qualms would be unfounded. But the derivation of economic laws depends on incomplete premises, simplifications concerning initial conditions, and a vague additivity as
sumption. So there are ample grounds for skeptical doubt. The difficulty for Mill seems insuperable. Although a messy derivation of an economic
generalization from simplifications, plausible ceteris paribus laws, and an
additivity assumption can increase one's confidence in the correctness of
the generalization, the deductive method does not provide the sort of
decisive supporting argument that Mill thought sciences ought to provide for their conclusions, unless there are grounds to take the component causes as additive.
304 DANIEL M. HAUSMAN
Mill might appear to close this gap in his argument for a deductive economics in the following famous passage:
The laws of the phenomena of society are, and can be, nothing but the laws of the actions and passions of human beings united together in the social state. Men, however, in a state of society, are still men; their actions and
passions are obedient to the laws of individual human nature. Men are not, when brought together, converted into another kind of substance, with different properties; as hydrogen and oxygen are different from water. . . .
Human beings in society have no properties but those which are derived from, and may be resolved into, the laws of the nature of individual man. In social phenomena the Composition of Causes is the universal law. (Logic, 6.7.1)
There are two serious problems with this quotation. First, since one is not, in Mill's view, able to acquire appreciable knowledge of social
phenomena without employing the deductive method, one cannot know
whether Mill's claims about the relations between social phenomena and
human nature are true without taking for granted what Mill is trying to
show. Second, this passage is stronger on assertion than on argument. Mill
argues only that the psychological laws governing human beings in
society are the psychological laws governing individual human beings, but nothing follows from this concerning the character of social laws in
general. To reach the conclusion that "the laws of the phenomena of
society are, and can be, nothing but the laws of the actions and passions of human beings united together in the social state" Mill needs to show
that all laws of social phenomena derive from the laws of psychology and
of the natural sciences. Mill has not provided such an argument, and by
addressing the different question of the relations between the properties of
compounds and constituents, he has muddied the waters. For many prop erties of societies (consider, for example, social mobility or rate of
increase of the money supply) resemble properties of individual human
beings as little as the properties of water resemble those of hydrogen. Mill does not believe that the additivity of effects always obtains, and
he goes on immediately after the passage just quoted to write,
This principle [of the Composition of Causes], however, by no means
prevails in all departments of the field of nature. The chemical combination of two substances produces, as is well known, a third substance with proper ties different from those of either of the two substances separately, or of both
THE COMPOSITION OF ECONOMIC CAUSES 305
of them taken together. Not a trace of the properties of hydrogen or of oxygen is observable in those of their compound water. (Logic, 3.6.1)
The composition of causes is here identified with a third principle, which one might call "the summation of properties." Mill finds that the
phenomena of chemistry are not mechanical, because many of the prop erties of compounds are not "sums" of the properties of their constituents, even though they might be literally deducible from generalizations governing their constituents and how they combine. Mill slides back and
forth between questions concerning (1) what can be deduced about
complex subject matters from a knowledge of the "laws" governing indi
vidual causal factors and principles of combination, (2) whether effects of causes can be "added," and (3) whether the properties of compounds are
similar to those of their constituents.
Although the composition of causes is not true of all phenomena, nevertheless
The former case, that of the Composition of Causes, is the general one; the other is always special and exceptional. There are no objects which do not, as to some of their phenomena, obey the principle of the Composition of Causes; none that have not some laws which are rigidly fulfilled in every combination into which the objects enter. The weight of a body, for instance, is a property which it retains in all the combinations in which it is placed. (Logic, 3.6.2)
Mill's grounds for making the general metaphysical claim of the prepon derance of additivity are that all objects "obey the principle of the Composition of Causes" with regard to some of "their phenomena," but this is just what one would expect if physical properties are mechanical and all objects have some physical properties. This fact, if it is a fact, would not justify the conclusion that "The former case, that of the Com
position of Causes, is the general one." And even if this conclusion were
justified, it would not in turn provide a strong reason to regard the messy deductions from simplifications and psychological laws as social laws.
There is nothing here to fill the gap for Mill and to justify employing the deductive method.
Someone who follows Mill's prescriptions for economics identifies a
set of potentially significant causes of the phenomena of interest, ascer
tains their separate laws, and, assuming additivity, "adds up" their sepa rate effects to determine their joint effects. If the results fit the data, then
306 DANIEL M. HAUSMAN
one concludes that one has causal knowledge of the phenomena of
interest. Even in the best of cases, this method is precarious because of the
additivity assumption. Deriving generalizations in this way surely gives one some further reason to believe that they are true and explanatory, but
the process only provides secure justification for the derived laws when
the deductive method turns out not to be necessary after all.
Daniel M. Hausman
University of Wisconsin, Madison
NOTES
*I am indebted to Elliot Sober for a very helpful conversation concerning these matters, and to Nancy Cartwright and Uskali M?ki for helpful criticism of a rough draft. An ancestor of this paper was delivered at a conference at Notre Dame University in 1991, and I profited from criticism from the audience there and especially from Wade Hands.
1. A System of Logic (1843) (London: Longmans, Green & Co., 1949), Bk. 2, ch. 3, sec. 3. References to A System of Logic will be incorporated into the text in the form,
"Logic, 2.3.3."
2. The so-called inverse deductive method seems a strained attempt to defend large scale historical speculation of the sort that Mill admired in Comte. In principle there is nothing strained or questionable about the inverse deductive method. Like the direct
deductive method, one "deduces" a social regularity from the underlying causal laws and a description of the particular circumstances. What makes Mill call it the "inverse
deductive method" is just that the social regularity is first derived from observation, rather than obtained from the deduction, so that the deduction rather than the observation serves
as a verification that the regularity is indeed a derivative causal law. But in his discussion of the inverse deductive or historical method, Mill greatly relaxes the demand that the social regularity be deduced from underlying causal laws. Mill argues that merely showing that empirical social regularities are not ruled out by the causal laws is enough to lend some weight to them (Logic, 6.10).
3. Compare this to Mill's own example in Logic, 3.10.6. 4. Surely Mill's father might have given the same argument in his own defense. There
is an irony here in the fact that recent extensions of neoclassical economic models to
politics largely recapitulate James Mill's account of political behavior. See, for example, James Buchanan, The Limits of Liberty: Between Anarchy and Leviathan. (Chicago: Uni versity of Chicago Press, 1975).
5. Compare J. S. Mill, On the Definition of Political Economy and the Method of In vestigation Proper to It" (1836), reprinted in Collected Works of John Stuart Mill, vol. 4 (Toronto, Canada: University of Toronto Press, 1967), pp. 325-26 and Logic, 3.9.3 and 6.9.1, and see Neil De Marchi, "Discussion: Mill's Unrevised Philosophy of Economics: A Comment on Hausman," Philosophy of Science, 53 (1986), 89-100. Mill writes, "To
THE COMPOSITION OF ECONOMIC CAUSES 307
verify the hypothesis itself a posteriori, that is, to examine whether the facts of any actual case are in accordance with it, is no part of the business of science at all, but of the appli cation of science' ("On the Definition of Political Economy," p. 325). It is not clear from
the text of Mill's writings whether Mill regarded the deductive method as a distinctive method of theory appraisal or whether he regarded it as the implementation of standard inductive methods when theorizing about complex phenomena. I am indebted to Abraham Hirsch for my understanding of these problems.
6. This is the interpretation of economic "laws" I defend in ch. 8 of The Inexact and
Separate Science of Economics (Cambridge: Cambridge University Press, 1992). 7. For further discussion of the peculiarities involved in "adding" component forces,
see Nancy Cartwright, "Do the Laws of Physics State the Facts?" In How the Laws of Physics Lie (Oxford: Clarendon Press, 1983), pp. 54-73, Lewis Creary, "Causal Explana tion and the Reality of Natural Component Forces," Pacific Philosophical Quarterly, 62 (1981), and Malcolm Forster, "The Confirmation of Common Component Causes," In A.
Fine and J. Leplin, eds. PSA 1988, vol. 1 (East Lansing: Philosophy of Science Associa tion, 1988), pp. 3-9.
8. See Natures Capacities and their Measurement (Oxford: Oxford University Press,
1989), esp. ch. 4.
9. But note that demand curves are decomposed into income and substitution effects
rather than built up from them. As I discuss below, much of economics does not in fact
involve "adding" of the sort that Mill has in mind. 10. Additivity is assumed in the treatment of technological improvements, but that part
of the theory is so unsuccessful that no support for the deductive method can be found in it.
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