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Closet Dualism and Mental Causation

Published online by Cambridge University Press:  01 January 2020

Brian Leiter
Affiliation:
University of Texas at Austin, Austin, TX78705, USA
Alexander Miller
Affiliation:
University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom

Extract

Serious doubts about nonreductive materialism — the orthodoxy of the past two decades in philosophy of mind — have been long overdue. Jaegwon Kim has done perhaps the most to articulate the metaphysical problems that the new breed of materialists must confront in reconciling their physicalism with their commitment to the autonomy of the mental. Although the difficulties confronting supervenience, multiple-realizability, and mental causation have been recurring themes in his work, only mental causation — in particular, the specter of epiphenomenalism — has really captured the interest of philosophers in general in recent years.

This growing attention has spawned a large body of literature, which it is not our aim here to explore or assess. Rather, we want to call attention to what we believe is a new and quite different argumentative strategy against epiphenomenalism voiced in some recent articles by Tyler Burge and Stephen Yablo. Each has challenged two central assumptions of the existing mental causation debate.

Type
Research Article
Copyright
Copyright © The Authors 1998

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References

1 We use ‘physicalism’ and ‘materialism’ interchangeably.

2 See, e.g., ‘Causality, Identity, and Supervenience in the Mind-Body Problem,’ Midwest Studies in Philosophy 4 (1979) 31-50; Physicalism and the Multiple Realizability of Mental States,’ in Block, N. ed., Readings in Philosophy of Psychology, Volume One (Cambridge, MA: Harvard University Press 1980)Google Scholar; ‘Concepts of Supervenience,’ Philosophy and Phenomenological Research 45 (1984) 153-76; ‘The Myth of Nonreductive Materialism,’ Proceedings and Addresses of the APA 63 (1989) 31-47; ‘Mechanism, Purpose, and Explanatory Exclusion,’ Philosophical Perspectives 3 (1989) 77-108; ‘Multiple Realization and the Metaphysics of Reduction,’ Philosophy and Phenomenological Research 52 (1992) 1-26. A number of these papers are now re printed in his Supervenience and Mind (Cambridge: Cambridge University Press 1993).

3 We are hopeful that supervenience and multiple realizability will soon come in for similar scrutiny.

4 ‘Philosophy of Language and Mind, 1950-1990,’ Philosophical Review 101 (1992) 3-51, esp. 36-9; Mind-Body Causation and Explanatory Practice,’ in Heil, J. & Mele, A. eds., Mental Causation (Oxford: Clarendon Press 1993), 97120Google Scholar. All further citations will be included in the body of the text; the former article will be cited as PLM; the latter, as MBC.

5 ‘Mental Causation,’ Philosophical Review 101 (1992) 245-80. All further citations will be included in the body of the text.

6 We shall sometimes speak of ‘explanatory relevance’ and ‘explanatory primacy.’ We will assume (controversially, but not implausibly) that explanations must identify causes.

7 We shall speak only of ‘causal relevance’ in what follows, with the understanding that we always mean relevance relative to event-types.

8 More precisely, ‘type-epiphenomenalism’ about the mental: ‘Events can be causes in virtue of falling under physical types, but events cannot be causes in virtue of falling under mental types’ (McLaughlin, BrianType Epiphenomenalism, Type Dualism, and the Causal Priority of the Physical,’ Philosophical Perspectives 3 [1989] 109–10)CrossRefGoogle Scholar.

9 Formulated aptly by Yablo: ‘If a property x is causally sufficient for an event y, then no property x* distinct from x is causally relevant to y’ (247). Read x as a physical property and x* as a non-identical (but supervening) mental property, and you have the argument for epiphenomenalism of the mental. Kim summarizes the exclusion argument this way: ‘a cause, or causal explanation, of an event, when it is regarded as a full, sufficient cause or explanation, appears to exclude other independent purported causes or causal explanations of it’ (‘The Myth of Nonreductive Materialism,’ 44).

10 Note that the problem does not arise for someone who accepts the type-identity of the mental and physical, since then CT would be false: things that are the same cannot compete for causal relevance.

11 See, e.g., LePore, Ernest and Loewer, BarryMind Matters,’ Journal of Philosophy 84 (1987) 630–42Google Scholar; Fodor, JerryMaking Mind Matter More,’ Philosophical Topics 17 (1989) 5979CrossRefGoogle Scholar.

12 ‘Mind Doesn't Matter Yet,’ Australasian Journal of Philosophy 72 (1994) 220-8

13 Burge almost says as much (cf. PLM 38-9), though he never actually utters the ‘D’ word. By contrast, Yablo keeps his dualism in the closet, presenting his argument as one made on behalf of the mere property dualism of the nonreductive materialist.

14 Burge does remark that he thinks mental causation can be accounted for within the traditional nonreductive ‘materialistic framework’ (PLM 38; MBC 97, 117-18).

15 Burge finds this characterization appropriately vague, and points out that it ‘does not entail an identity theory in ontology. It does require some sort of materialism about the mind’ (PLM 31). He goes on to distinguish nonreductive materialisrns which hold only token-identity (PLM 34) and those ‘more liberal materialism[s)’ which hold that mental events ‘are always constituted of events that are instances of physical natural kinds’ (PLM 35).

16 Cf. MBC 117: ‘As long as mentalistic explanation yields knowledge and understanding, and as long as that explanation is (sometimes) causal, we can firmly believe that mind-body causation is a part of the world … mentalistic explanation and mental causation do not need validation from materialist metaphysics.’

17 Cf. Philip Kitcher's claim that the ‘rejection of the a priori’ is a central component of naturalism in ‘The Naturalists Return,’ Philosophical Review 101 (1992) 113. See also the discussion of ‘methodological naturalism’ in Railton, PeterNaturalism and Prescriptivity,’ in Paul, E. et al., eds., Foundations of Moral and Political Philosophy (Oxford: Basil Blackwell 1990), 156–7Google Scholar and Laudan, LarryNormative Naturalism,’ Philosophy of Science 44 (1990) 4459, esp. 44CrossRefGoogle Scholar. For a general overview of recent naturalisms, see Leiter, BrianNaturalism and Naturalized Jurisprudence,’ in Bix, B. ed., Analyzing Law: New Essays in Legal Theory (Oxford: Oxford University Press 1998)Google Scholar.

18 Cf. MBC 116: ‘we know that the two causal explanations [one physicalistic, one mentalistic] are explaining the same physical effect as the outcome of two very different patterns of events. The explanations of these patterns answer two very different types of inquiry. Neither type of explanation makes essential, specific assumptions about the other.’

19 Cf. Büchner, Ludwig Force and Matter, trans. Collingwood, J.F. (London: Trubner 1870)Google Scholar; Lange, Friedrich The History of Materialism, trans. Thomas, E.C. (New York: Harcourt, Brace 1925; Humanities Press 1950)Google Scholar, esp. Book Two, 3rd Sec., Ch. II (‘Brain and Soul’). Büchner, a medical doctor, wrote his book in 1855 as a popular guide to the new scientific developments of the day, and how they must change our concept tions of consciousness, free will, and human character; it became one of the most successful books of the nineteenth century, earning the reputation as the ‘Bible’ of materialism (it was even the book that sparked the young Einstein's interest in science [cf. Gregory, Frederick Scientific Materialism in Nineteenth Century Germany (Dordrecht: D. Reidel 1977), 155])CrossRefGoogle Scholar. Lange's book, originally written in 1866, was a similarly influential, if more critical, account of materialist positions from antiquity through the nineteenth century. Readers of Büchner and Lange will quickly recognize crude versions of materialist positions that we now associate with the likes of Smart and the Churchlands.

20 It thus seems false to assert, as Burge does, that ‘Materialism is not … even clearly supported, by science’ (MBC 117). But surely the whole of modern science supports the claim, as we put it in the text, that ‘disembodied spirits and immaterial properties’ did not turn out to be explanatorily fruitful posits. Burge's shaky grasp of the relevant science is suggested when he goes so far as to claim, falsely, that it is ‘very unlikely’ that chemistry and physiology are reducible to physics (MBC 102).

21 We can put this point in more explicitly Burgean terms. On Burge's MN we draw ‘the relevant methods … from reflection on what works in actual explanatory practice’ (PLM 39). But Burge does not tell us what to do when methods that work in different domains presuppose different ontologies. The explanatory practices of the neuroscientist simply may not jibe with the explanatory practices of the psychologist. That is precisely what creates the philosophical problem in the first place! It seems philosophically unsatisfying to simply accept, uncritically, the ontological presuppositions of each explanatory practice, which is what Burge would have us do.

22 Cf. Suppe, Frederick The Structure of Scientific Theories, 2nd ed. (Urbana: University of Illinois Press 1977), 119–90, 617-730Google Scholar.

23 These are ruled out by the requirement of a biconditional bridge law, rather than allowing for reduction via material conditionals alone.

24 Cf. Schwartz, JustinMaterialism and the Unity of Science’ (Unpublished dissertation, University of Michigan, 1989)Google Scholar: ‘as kinds and laws are used in actual science, they are not inconsistent with accepting disjunctive predicates as kind terms or disjunctive generalizations as laws’ (303). See generally, Causey, Robert Unity of Science (Dordrecht: D. Reidel 1977)Google Scholar; Enc, BerentIn Defense of the Identity Theory,’ Journal of Philosophy 76 (1983) 279–97CrossRefGoogle Scholar.

25 Cf. Kim, ‘The Myth of Nonreductive Materialism,’ 39Google Scholar. In a recent paper (‘Multiple Realization and the Metaphysics of Reduction’), Kim has made a further point about multiple realizability:

It may be that these [physical] structures [which are to form the reduction bases] are so finely individuated and so few actual individuals fall under them that research into the neural bases of mental states in these structures is no longer worthwhile, theoretically or practically. What we need to recognize here is that the scientific possibility of, say, human psychology is a contingent fact (assuming it is a fact); it depends on the fortunate fact that individual humans do not show huge physiological-biological differences that are psychologically relevant. But if they did, that would not change the metaphysics of the situation one bit; it would remain true that the psychology of each of us was determined by, and locally reducible to, his neurobiology. (21)

This strikes us as correct: but it means that the most influential consideration counting against the metaphysical doctrine of reductive materialism — namely, multiple realizability — is actually irrelevant.

26 Cf. Yablo, 247-8 & 247 n. 5.

27 As Jaegwon Kim has pointed out to us, one might wonder even about this claim — and, indeed, Yablo presents no real argument in its favor. For purposes of the argument here, we shall grant Yablo's intuitive sense that determinates and determinables do not compete for causal relevance.

28 Note that it is not entirely clear that this can be what is involved in nonreductive materialism, or at least those versions which incorporate the thesis of the anomalism of the mental. The inclusion of strong supervenience (part [i]) would collapse into the claim that there can be laws which connect the mental and the physical, unless the nonreductive materialist is provided with some conception of law other than that which characterizes laws as counterfactuals supporting generalizations. (We are indebted here to John Divers.)

29 See especially, ‘Mental Events,’ ‘Psychology as Philosophy,’ and ‘The Material Mind,’ all reprinted in Davidson's, Essays on Actions and Events (Oxford: Clarendon 1980)Google Scholar.

30 Here we follow Kim's, Jaegwon interpretation of Davidson in ‘Psychophysical Laws,’ in LePore, E. and Loewer, B. eds., Actions and Events: Perspectives on the Philosophy of Donald Davidson (Oxford: Basil Blackwell 1985)Google Scholar. But for some worries about Kim's interpretation, see Miller, AlexanderSome Anomalies in Kim's Account of Davidson,’ Southern Journal of Philosaphy 31 (1993) 335–44CrossRefGoogle Scholar.

31 ‘Psychology as Philosophy,’ 231

32 Remember that our central claim is only that the nonreductive materialist can not avail himself of Yablo's argument; we are not passing judgment here on the soundness of the Davidsonian argument as a defense of nonreductive materialism.

33 In a sense, we can view this talk about the nature of the governing constitutive ideals as after all providing a conceptual element to the traditional relation of determination. Yablo quite rightly rejects the conceptual entailment condition, but that is only one way of inserting a conceptual component into the determination relation. Our condition is another way of doing this, immune to the sorts of considerations Yablo cites against the conceptual entailment condition. Even though we discover that, e.g., salt and sodium chloride are identical by a posteriori investigation, we can still know a priori whether the constitutive ideals which govern their ascription aim in each case at the same sort of intelligibility.

34 Of course, Yablo might claim that what is crucial here is an even more restricted version of the exclusion principle which trades not in determination as such, but rather in the weaker relation of asymmetric necessitation, i.e. something like this: If a property X is causally sufficient for an event y, then no property x* distinct from X is causally relevant to y; but if X and x* stand in the asymmetric necessitation relation, it does not follow that x* is causally irrelevant toy. The failure of the conceptual component in the mental-physical case just invoked would of course be impotent against an argument driven by a more restricted exclusion principle of this nature. But we shall not attempt to deal with this point here. For one thing, it is not the principle actually used by Yablo in his paper. More importantly, Yablo attempted to back up his original exclusion principle by appealing to uncontroversial and paradigmatic examples of the determination relation in order to pump our intuitions concerning causal relevance. But if he moves to the more restricted version, he will no longer be entitled to these intuitions as such. So he would still face the (non-trivial) task of finding some new intuitive backing for the more restricted version of the exclusion principle.

35 Yablo actually goes on to say, ‘Overladen as they are with physical details far beyond the effects causal requirements, it is the physical phenomena which are liable to disqualification on grounds of superfluity’ (250). This would be a startling departure from physicalism. But we needn't discuss this here. If our objections to Yablo's attempts to save the causal relevance of mental properties are sound, this strong dualist claim is already undercut: if mental properties are causally irrelevant they can't even compete with physical properties vis-a-vis Yablo's ‘commensuration constraint’ (274), let alone win that competition.

36 Burge is, of course, more explicit regarding his ambivalence about materialism, though even he resolutely avoids speaking of ‘dualism.’ And while Yablo speaks of ‘dualism,’ it is merely the familiar property dualism of the nonreductive materialist.

37 Cf. ‘Concepts of Supervenience’ and ‘The Myth of Nonreductive Materialism,’ Section IV. See also Schiffer, Stephen Remnants of Meaning (Cambridge, MA: The MIT Press 1987), 153–4Google Scholar.

38 Namely, reduction or eliminativism.

39 Cf. ‘The Myth of Nonreductive Materialism,’ Section III and ‘Multiple Realization and the Metaphysics of Reduction,’ esp. 20-1.

40 Mental causation just would be physical causation.

41 The Antichrist, Section 14

42 More precisely, Burge has given an unsuccessful ‘naturalistic’ argument for what is, in effect, dualism; while Yablo's dualism has masqueraded as nonreductive materialism, and thus has received no independent defense.

43 McDowell, John Mind and World (Cambridge, MA: Harvard University Press 1994)Google Scholar. McDowell, of course, regards his brand of anti-materialism as avoiding the pitfalls of Cartesianism.

44 See also our ‘Mind Doesn't Matter Yet.’

45 For useful comments or discussion, we are grateful to anonymous referees for this journal and to John Divers, Ken Gemes, Frank Jackson, Jaegwon Kim, William Lycan, Philip Pettit, and Stephen Yablo — none of whom, it goes without saying, should be presumed to agree fully with our conclusions.