The Southern Journal of Philosophy (1993) Vol. XXXI, No. 3

SOME ANOMALIES IN KIM’S ACCOUNT OF DAVIDSON Alexander Miller University of Michigan

Davidson’s thesis of psychophysical anomalism is the view that there are no strict laws connecting the mental with the physical. In this paper I shall look at one recent and initial- ly attractive attempt to pin down and clearly state Davidson’s argument for the nonexistence of strict psychophysical link- ages, that presented by Jaegwon Kim in his “Psychophysical laws” ([5]).’ I shall argue that no matter how hard we try to make something of Kim’s interpretation, it either portrays Davidson as proposing a fundamentally implausible argument, or misrepresents important facets of Davidson’s position.

Kim suggests that the skeletal structure of Davidson’s argu- ment is as follows:

The mental system has a certain essential characteristic X and the physical system a certain essential characteristic Y, where X and Y are mutually in- compatible. Laws linking the two systems, if they exist, would “transmit” these characteristics from one system to the other, leading to incoherence. Therefore, there can be no laws connecting the mental with the physical so long as the two systems are to retain their distinctive identities. (p. 375)

Briefly, attributions of mental states are governed by consti- tutive principles of rationality, consistency, and coherence, principles which have no counterparts (or “echo,” as Davidson puts it ([2], p. 231)) in the constitutive principles governing the construction of physical theories: the mental and physical realms are governed by constitutive principles that aim a t dif- ferent sorts of intelligibility. If there were strict psychophys- ical laws, attributions of mental states could be decided by the nonrational principles governing physical science-this would result in incoherence because we would have preempted the constitutive principles of rationality, and so on, which are sup- posed to be definitive of the mental realm.

Alexander Miller is a graduate of the Universities of Glasgow, St. Andrews, and Michigan. He is currently completing a doctoral thesis on the philosophy of language and metaphysics at the University of Michigan, Ann Arbor. His previous publications have appeared in The Southern Jour- nal of Philosophy, Analysis, and Mind.

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Kim provides us with a couple of detailed examples in order to throw the problem into sharper relief (section IV). Suppose that m l and m2 are mental states such that the constitutive principles governing interpretation imply that whenever the attribution of one is warranted, the attribution of the other is not. Suppose also that there are neural states n l and n2 which are nomologically coextensive with m l and m2, respectively, and that n l and n2 have C1 and C2 as their respective at- tribution conditions.2 We would thus have

(1) Necessarily, if C1 obtains, then n l occurs, (2) Necessarily, m l occurs iff n l occurs,

which together would allow us to generate

(3) Necessarily, if C1 obtains, m l occurs.

Similar reasoning from the relevant psychophysical law for m2, and the attribution condition for n2, would allow us to generate

(4) Necessarily, if C2 obtains, m2 occurs.

We would thus have purely physical attribution conditions for m l and m2, and, as Kim puts it,

the constitutive principles of the mental] as essential constraints on the attribution of mental states are in danger of being preempted, or seriously compromised, for the determination of whether these physical attribution conditions obtain is not subject to the constraint of this principle. (3) and (4) would permit us to attribute intentional mental states independently of [e.g.] the rationality maximisation rule; a t least, they would force this rule to share its jurisdiction over mental attributions. (pp. 378-379)

Because the attribution of m l and m2 would no longer be gov- erned by the constitutive principles of the mental, we would in effect no longer be dealing with anything that could prop- erly be called mental-we would have “changed the subject.”

Another example: suppose that p is the statement “Ypsilanti is within 10 miles of Ann Arbor,” and that q is the statement “Ypsilanti is within 20 miles of Ann Arbor.” Then it is plaus- ible that the following counterfactual is grounded in the prin- ciple of rationality maximization:

(5) If S were to believe p, he would also believe q.

Now suppose that believing p and believing q are nomolog- ically coextensive with the purely physical states B1 and B2, respectively. Then, in addition to (5) , we also have

(6) Necessarily, a person believes p iff he is in state B1, (7) Necessarily, a person believes q iff he is in state B2.

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These give us:

(8) If s were in state B1, he would also be in state BZ3

Kim suggests that the difficulty Davidson has in mind here for the advocate of psychophysical laws is that he has no account of what could ground or explain this purely physical dependency. He cannot plausibly claim that it is physically fundamental, “a basic law of physical theory requiring no ex- planation,” since we would not expect a fundamental law to connect physical states as complex as the neural correlates of beliefs. Nor can he claim that it is explainable in terms of other, more fundamental physical laws: such laws then would enable us to explain (via (€9, (6), and (7)) why (5) holds, pre- empting the role of the rationality maximization principle as a ground for (5), so that “the concept of belief has effectively been removed from the jurisdiction of this principle” (pp. 380- 381). Nor can he claim both that (8) is not basic and that it lacks any physical explanation, since “then we can explain it psychologically in terms of (5) via (6) and (7)’ as it was orig- inally derived. But this is absurd: to ground a purely physical dependency in considerations of rationality of belief would have to be taken as an intolerable intrusion on the closedness and comprehensiveness of physical theory” (p. 381). These con- siderations, Kim suggests, should make us sceptical about the likes of (6) and (7).

Kim finds these arguments “intriguing and appealing,’’ and they certainly do have the merit of stating in a n extremely clear form an otherwise somewhat obscure and difficult argu- ment. I want to suggest, however, that they are less plausible than Kim would have us believe, due to a crucial ambiguity which underlies his position.

It seems to me that there are two ways of reading the notion of a constitutive principle. In the first sense, a set of principles is constitutive for a given theory if those principles necessarily have to be used or applied in deciding the truth-values of the sentences or propositions that make up the output of the the- ory. The basic idea is that if we can decide the truth-values of the relevant sentences without even having to bother to consult a given set of principles, then the principles cannot be constitutive vis-a-vis the theory of which these sentences are a part. Using this interpretation of “constitutive principle” it is easy to see how Davidson’s argument would progress on Kim’s interpretation: the a priori principles of rationality and their kin could no longer be viewed as constitutive because we could gen- erate answers about the mental life of an agent by applying the new principles-ex hypothesi devoid of constitutive norms of

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rationality-instead. For example, we could attribute mental state m l to an agent on the basis of (3) alone, bypassing the constitutive principles of rationality-and on the current con- ception of “constitutive” this would indeed be incoherent.

Plausible as it initially sounds, this way of interpreting Davidson is unacceptable, for on this way of construing “con- stitutive” the argument turns out to be completely trivial-a mere analytic consequence of the adopted definition of “con- stitutive.” For, of course, of any group of two or more sets of principles each of which is sufficient for determining the rele- vant truth-values, it cannot be the case that both of them have to be used or applied in determining the truth-values: for ex hypothesi, each group is individually sufficient, thus preclud- ing the necessity of referring to the other set. An analogy with the notion of an essential property might help to make this clearer. Suppose we were to take the essential properties of a n object as those that had to be used in individuating it. Then it would follow trivially that no object could have more than one essential property: for, of any pair of putatively essential properties, we could always have simply used the other in individuating the object. Of course, such a conception of the notion of an essential property would be bizarre-what I am suggesting is that the first way of interpreting the notion of “constitutive principle,’’ though not obviously so, is neverthe- less equally outlandish.

Is there a n alternative and more plausible construal of the notion of constitutive principle that can do the job? There is a more plausible candidate, suggested in an obvious way by the more usual reading of a n essential property: according to this, a property is essential if the object in question necessarily possesses it-but there is no suggestion that whenever we in- dividuate the object we do so by means of that property. Thus, Jones is essentially a rational animal, since Jones is a man, and men are essentially rational animals. But there is no sug- gestion that the only way we individuate Jones is via his pos- session of the property of being a rational animal. J u s t as we say that a n essential property is simply a property which that individual must have, we can also say that a set of principles is constitutive with respect to a given theory if the output of that theory-the sentences which make up the body of the theory-have to satisfy the constraints laid down by those principles. In other words, we do not necessarily need to use the principles in generating the output, but once generated, by whatever means, the sentences in question have to at least satisfy those constraints.

Now it is not, on this interpretation, a trivial definitional

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consequence that a given domain or theory cannot be subject to two sets of constitutive principles: just as there is nothing incoherent in the idea of Jones having both the essential property of being a rational animal and the essential property of being a featherless biped, there is nothing incoherent per se in the claim that the output of a given theory has to satisfy two sets of constitutive principles. Unless, that is, the two sets of constraints or principles are incompatible themselves, or can generate incompatible results. So in the case of the men- tal/physical we would need an argument from Kim or Davidson to the effect that the constitutive principles governing interpre- tation and the constitutive principles governing physical science are incompatible, or could together generate incompat- ible results.

I think there are a t least two comments that we can make on this. First, Davidson actually seems to deny this at one point. At the beginning of “The Material Mind” whilst dis- cussing Art, “a machine that, when exposed to the lights and sounds of the world, mimics the motions of a man” ([3], p. 245), and which has been constructed such that we “could explain in physical terms why Art moved as he did when subjected to various stimuli’’ (ibid., p. 246), and whose construction Davidson certainly thinks is a t least in principle possible, he says, “Art would prove that however different they may be, there is no conflict between the modes of explanation of phys- ical science and of psychology” (ibid., p. 247, my emphasis). Thus we seem to have Davidson here denying a premise that would be crucial for his argument, if indeed he were arguing as Kim suggests. This should begin to make us doubt Kim’s interpretation.

Secondly, the argument as it stands does not seem to work anyway. To see this, we can go back and re-examine the first of Kim’s two detailed examples. Remember in that example we supposed that the constitutive principles of interpretation enjoined that whenever we had grounds for attributing ml , we thereby had grounds for refusing to attribute m2, and vice ver- sa. Now, could our attribution conditions (3) and (4) generate a result incompatible with this deliverance of the constitutive principles of rationality? Well, suppose empirical investigation told us that the conditions C1 and C2 obtained simultaneous- ly-then (3) and (4) would commit us to the simultaneous as- signment of m l and m2, contrary to the deliverances of the constitutive principles of rationality. But note that there is a hostage to fortune here: for might it not be the case that there is, as a matter of empirical fact, a nomological correlation

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between C1 and C2? That is to say, might it not be the case that the following is a lawlike truth of physical science:

(9) Necessarily, C1 obtains iff C2 does not.

If something along the lines of (9) obtains, the nomological interrelationships of our attribution conditions will mirror the rationally grounded relationships among our propositional attitudes, in such a way that conflict between the constitutive principles of physics and interpretation could not be forthcom- ing.4 Of course, there might still be a question as to whom the onus of proof is on here-wouldn’t the argument still pose a problem for the defender of psychophysical laws, in the sense that he would now have the burden of establishing a body of laws like (9)? Or maybe the onus is on the Davidsonian to show that there are in fact no such laws? Either way, each of these questions seems to be beside the point in the context of trying to find a suitable interpretation of Davidson, for an- swering them would definitely require some kind of a posteriori investigation, whereas Davidson’s argument against the exis- tence of strict psychophysical laws is supposed to stem from purely a priori considerations.5 Again, this makes Kim’s inter- pretation of Davidson look somewhat doubtful.

However, maybe Kim could claim that there is a n argument of the requisite sort available to Davidson here-maybe we could re-use the line of argument from the second of Kim’s detailed examples, and ask: what could ground or explain the purely physical dependency (9)? Again, it seems implausible to suggest that it is a fundamental physical law: we would ex- pect such laws to correlate physical states a good deal simpler than the attribution conditions of propositional attitudes. And for similar reasons as before, the claim that it is neither fundamental nor physicalistically explicable is unappealing. But what now of the claim that it is a nonfundamental law, explicable in terms of more fundamental physical laws and states? The original objection to this would be that such fun- damental physical laws would then allow us to explain why (5) holds, preempting the role of the rationality principles as grounds for (5). But it should be clear that this line of argu- ment is not available in the present context, for the question at issue is whether such a situation would indeed preempt the role of the constitutive principles of rationality: the claim is, that if the nomological relations within that part of physical theory dealing with the attribution conditions of propositional attitudes mirror the structural interrelationships posited among our beliefs by the constitutive principles of rationality,

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there won’t be such preempting. So the preempting argument can only be used here on pain of begging the question.

Where does this leave Kim’s interpretation of Davidson? On one reading of “constitutive principle,” the argument he attrib- utes to Davidson works, but in a completely trivial manner. On the more plausible reading of “constitutive principle,” the argument rests on an assumption that Davidson appears to deny, and if it worked-and it is by no means clear that it does-it would work only a posteriori. I will finish by looking a t two suggestions Kim might make in order to stop up the gaps in the argument he attributes to Davidson.

Firstly, Kim could suggest that underlying the argument for psychophysical anomalism is what he terms the explanatory- exclusion thesis: the thesis that no phenomenon can have more than one complete and independent explanation.6 If psychophysical laws were possible, for a given event explica- ble in terms of the constitutive principles of psychology, we would have, courtesy of those physical properties nomologi- cally coextensional with the relevant psychological properties, deductive-nomological explanations of the same event in terms of the laws of physical science. If the explanatory-ex- clusion thesis were correct, and if it could be argued that the relevant explanations were complete and independent, then this would be sufficient to rule out the possibility of the ex- istence of strict psychophysical laws.

Obviously, this argument could do with a deal of sharpening up and defense-for one thing, it is not transparently clear that the relevant explanations are really independent. But as I am about to independently reject it as an interpretation of Davidson, I shall not take upon myself the burden of shar- pening it up.

The above suggestion won’t do as an interpretation of Davidson for the following simple reason: Davidson makes it quite clear (and Kim acknowledges this in his exposition) that the argument for psychophysical anomalism hinges on the fact that the mental and the physical owe allegiance to dif- ferent sorts of constraints and constitutive principles. But an argument from the explanatory-exclusion thesis to psycho- physical anomalism would not take this into account, for that thesis would rule out any two complete and independent ex- planations of a phenomenon regardless of whether those ex- planations were furnished by theories which owed allegiance to different types of constitutive principle-the explanatory- exclusion thesis would even rule out two complete and inde- pendent explanations of a phenomenon from within the same domain or t h e ~ r y . ~ This should be sufficient to make the claim

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that the explanatory-exclusion thesis underlies Davidson’s argu- ment for anomalous monism implausible.8

Secondly, Kim might attempt to argue as follows. The char- acteristic feature of constitutive principles is that they are explanatorily fundamental, as opposed to explanatorily deriv- ative. Now, if we could explain every instantiation of the con- stitutive principles without reference to constitutive principles, then it would seem that you would thereby have the explan- atory resources a t your disposal to explain constitutive prin- ciples themselves by other means-in direct contradiction to the assumption of explanatory basicness. So we should read the claim of explanatory basicness as implying that all prin- ciples are not also explainable without reference to constitu- tive principles. But then, armed with this reading of “constit- utive principle,” we could block the crucial move in the argu- ment we gave above. Toward the end of that argument, we claimed that the fact that more fundamental physical laws could be used to explain why (5) holds could be not be taken to show that the constitutive principles of rationality had been preempted on pain of begging the question. This move could now be blocked, because given the suggested construal of “con- stitutive principle,” the situation envisaged-the explanation of (5) in terms of more fundamental physical laws-would indeed “preempt the role of rationality principles as grounds for (3,” since this would demonstrate that such principles were only explanatorily derivative: their essentially explana- tory role would have been compromised.

This is an interesting suggestion, and it might have some plausibility as an argument in its own right. But again I would reject it here on the grounds that it fails to capture the essence of Davidson’s argument against psychophysical laws. To see this, reflect again that Davidson’s argument for psy- chophysical anomalism turns on the claim that the mental and physical realms owe allegiance to different sorts of con- straints and constitutive principles-principles that aim at different kinds of intelligibility. But again, we could use the suggested reading of “constitutive principle” to rule out the possibility of strict laws obtaining even between separate re- gions of physical science. Consider the case of psychochemical laws. Clearly, there are constitutive principles of chemistry, dealing with molecular recombination and so on, which are jointly definitive of what chemistry is about. But given the suggested reading of “constitutive principle” we could run an analogous argument to the effect that the existence of strict psychochemical laws would preempt the essential explanatory role of the constitutive principles of chemistry. The conclusion

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would be that there can therefore be no psychochemical laws. So here we have an argument, exactly analogous to the one that uses the reading of “constitutive principle” suggested above, that would rule out the possibility of strict lawlike link- ages even between different regions within physical science. I t should be clear that this argument is much stronger than that adumbrated by Davidson: the suggested argument turns merely on the fact that there are different constitutive prin- ciples involved in each of the regions under consideration, rather than on the much stronger claim that the two regions owe allegiance to constitutive constraints that aim at different sorts of intelligibility. The constitutive principles of physics and chemistry aim at the same sort of intelligibility, but the suggested construal of Davidson’s argument would still rule out the possibility of there being strict lawlike linkages be- tween them. Since Davidson’s argument explicitly turns on the claim that the constitutive principles of the mental and physical realms aim at different sorts of intelligibility, the sug- gested construal of “constitutive principle” is out of place in a construal of the Davidsonian a r g ~ m e n t . ~

It seems then that Kim has provided us with no plausible interpretation of Davidson’s attack on the possibility of psy- chophysical laws-or at least no interpretation on which that attack itself is credible when construed as a n a priori argument. We are thus still lacking a clear and satisfying interpretation of Davidson’s argument for psychophysical anomalism.1°

NOTES

1 All references in the text and in the notes are to this paper, unless specified otherwise.

2 For the notion of an attribution condition, see p. 378. 3 Kim admits (p. 380) that this sort of inference is “tricky”-I won’t

question it here, as I claim the objection I am about to give works even if we grant Kim all of these inferences.

4 This notion of mirroring obviously owes something to the discussions of the “mirror constraint” that have been featured in Martin Davies’ work. See [4] for an account of this constraint.

5 Something which Kim himself notes with approval-see p. 373. 6 I should note that Kim nowhere (as far as I can see) actually envisions

such a role for the explanatoryexclusion thesis-this is just my own suggestion as to one way in which Kim might attempt to proceed.

Kim himself makes this quite clear in [7]. 8 And this is perhaps just as well, since it has been claimed that the

exclusion thesis is instrumental in establishing the causal inefficacy of mental properties. See e.g. [6] and [7].

9 We might also argue that the reading of “constitutive principle” is itself unappealing. Clearly, there are such things as constitutive principles of chemistry-principles which are definitive of the subject matter of that

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science. And we also think that there are strict psychochemical linkages. Chemists think that there are constitutive principles of their science, but they can also believe in the explanatory completeness of physics. But such a combination of views would be incoherent given the suggested reading of “constitutive principle,” and that should be sufficient to cast doubt on that reading. But to reiterate: my main argument against the suggested argument in the present context is tha t it cannot be Davidson’s argument, as it does not turn on the claim tha t the constitutive principles tha t are involved aim a t different sorts of intelligibility.

l o I would like to thank John Divers, J im Edwards, Brian Leiter, Joe Mendola, and a n anonymous referee for useful comments on a n earlier draft of this paper.

REFERENCES

[ l ] Davidson, Donald. Essays on Actions and Euents. Oxford, 1980. [2] Davidson, Donald. “Psychology as Philosophy,” reprinted in [l], 229-238. [3] Davidson, Donald. “The Material Mind,” reprinted in [l], 245-260. [4] Davies, Martin. “Tacit Knowledge and Semantic Structure: Can a 5%

[ 5 ] Kim, Jaegwon. “Psychophysical Laws,” in E. LePore and B. McGlaughlin

[6] Kim, Jaegwon. “Explanatory Realism, Causal Realism, and Explanatory

[7] Kim, Jaegwon. “Mechanism, Purpose, and Explanatory Exclusion,” Philo-

Difference Matter?,” Mind 96 (1987): 433-462.

(eds.), Actions and Euents. Basil Blackwell, 1985, 369-386.

Exclusion,” Midwest Studies in Philosophy 12 (1988): 225-240.

sophical Perspectives 3 (1989): 77-108.

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