Online research in philosophy

The recent literature on mental causation has not been kind to nonreductive, materialist functionalism (‘functionalism’, hereafter, except where that term is otherwise qualified). The exclusion problem2 has done much of the damage, but the epiphenomenalist threat has taken other forms. Functionalism also faces what I will call the ‘problem of metaphysically necessary effects’ (Block, 1990, pp. 157-60, Antony and Levine, 1997, pp. 91-92, Pereboom, 2002, p. 515, Millikan, 1999, p. 47, Jackson, 1998, pp. 660-61). Functionalist mental properties are individuated partly by their relation to the very effects those properties’ instantiations are thought to cause. Consequently, functionalist causal generalizations would seem to have the following problematical structure: The state of being, among other things, a cause of e (under such-andsuch conditions) causes e (under those conditions).3 The connection asserted lacks the contingency one would expect of a causal generalization. Mental states of the kind in question are, by metaphysical necessity, causes of e; any state that does not cause e is thereby a different kind of state. Yet, a mental state’s being the sort of state it is must play some causal role if functionalism is to account for mental causation.4 In what follows, I first articulate more fully the problem of metaphysically necessary effects. I then criticize three functionalist attempts to solve the problem directly. Given the failure of functionalist efforts to meet the problem head-on, I consider less direct strategies: these involve formulating functionalism or its causal claims in such a way that they appear not to generate the problem of metaphysically necessary effects. I argue against these indirect solutions, in each case concluding either that the problem still arises or that avoiding it requires the adoption of an unorthodox form of functionalism (itself a surprising result). In the final..

The functionalist conception of mental properties, together with their multiple realizability, is often taken to entail their irreducibility. It might seem that the only way to revise that judgement is to weaken the requirements traditionally imposed on reduction. However, Jaegwon Kim has recently argued that we should, on the contrary, strengthen those requirements, and construe reduction as what I propose to call “logical reduction”, a model of reduction inspired by emergentism. Moreover, Kim claims that what he calls “functional reduction” allows one to reduce (at least some) mental properties by these new standards. I argue against both theses. First, I present a counterexample to the emergentist model of reduction: The model judges irreducible certain properties which are clearly reducible. Second, I contestthat functional reduction as construed by Kim satisfies the emergentist constraints. Functional reduction implies, over and above a functional definition of the reduced property, the indication of its realizers. But the latter information corresponding to the discovery of a (local) bridge law, is empirical and not purely logical.

Recent discussions of mental causation have focused on three principles: (1) Mental properties are (sometimes) causally relevant to physical effects; (2) mental properties are not physical properties; (3) every physical event has in its causal history only physical events and physical properties. Since these principles seem to be inconsistent, solutions have focused on rejecting one or more of them. But I argue that, in spite of appearances, (1)–(3) are not inconsistent. The reason is that 'properties' is used in different senses in the principles. In (1) and (3), 'properties' should be read as 'tropes' (properties here are particulars), while in (2) 'properties' should read as 'types' (properties here are universals or classes). Although mental types are distinct from physical types, every mental trope is a physical trope. This allows mental properties to be causally relevant to physical effects without violating the closed character of the physical world.

Functional reductionism concerning mental properties has recently been advocated by Jaegwon Kim in order to solve the problem of the 'causal exclusion' of the mental. Adopting a reductionist strategy first proposed by David Lewis, he regards psychological properties as being 'higher-order' properties functionally defined over 'lower-order' properties, which are causally efficacious. Though functional reductionism is compatible with the multiple realizability of psychological properties, it is blocked if psychological properties are subdivided or crosscut by neurophysiological properties. I argue that there is recent evidence from cognitive neuroscience that shows that this is the case for the psychological property of fear. Though this may suggest that some psychological properties should be revised in order to conform to those of neurophysiology, the history of science demonstrates that this is not always the outcome, particularly with properties that play an important role in our folk theories and are central to human concerns.

It has been argued that nonreductive physicalism leads to epiphenominalism about mental properties: the view that mental events cannot cause behavioral effects by virtue of their mental properties. Recently, attempts have been made to develop accounts of causal relevance for irreducible properties to show that mental properties need not be epiphenomenal. In this paper, I primarily discuss the account of Frank Jackson and Philip Pettit. I show how it can be developed to meet several obvious objections and to capture our intuitive conception of degrees of causal relevance. However, I argue that the account requires large-scale miraculous coincidence for there to be causally relevant mental properties. I also argue that the same problem arises for two apparently very different accounts of causal relevance. I suggest that this result does not show that these accounts, on appropriate readings, are false. Therefore, I tentatively conclude that we have reason to believe that irreducible mental properties are causally irrelevant. Moreover, given that there is at leastprima facie evidence that mental properties can be causally relevant, my conclusion casts doubt on nonreductive physicalist theories of mental properties.

According to functionalism, mental state types consist solely in relations to inputs, outputs, and other mental states. I argue that two central claims of a prominent and plausible type of scientific realism conflict with the functionalist position. These claims are that natural kinds in a mature science are not reducible to natural kinds in any other, and that all dispositional features of natural kinds can be explained at the type-level. These claims, when applied to psychology, have the consequence that at least some mental state types consist not merely in relations to inputs, outputs, and other mental states, but also in nonrelational properties that play a role in explaining functional relations. Consequently, a scientific realist of the sort I describe must reject functionalism.

The aim of this paper is to defend the causal homogeneity of functional, mental properties against Kim’s attack. It is argued that (a) token identity is sufficient for mental causation, that (b) token identity implies a sort of functional reduction, but that (c) nonetheless functional, mental properties can be causally homogeneous despite being multiply realizable: multiple composition is sufficient for multiple realizability, but multiple composition does not prevent the realizers from having their pertinent effects in common. Thus, the causal exclusion problem provides no argument for abandoning the position that there are functional, mental properties that are natural kind properties.

Semifactuals and Epiphenomenalism

Mental properties are said to be epiphenomenal because they do not pass the counterfactual test of causal relevance. Jacob (1996) adopts the defence of causal efficacy of mental properties developed by LePore and Loewer (1987). They claim that those who argue for the epiphenomenalism of the mental place too strong a requirement on causal relevance, which excludes causally efficacious properties. Given a proper analysis of causal relevance, the causal efficacy of mental properties is saved. I defend the counterfactual test and epiphenomenalism of the mental against this critique. In causal counterfactuals we hold everything the same, take out the causal property and see if the effect property occurs. We do not replace the causal property with a barely different property as presupposed by LePore and Loewer. But I recognize some general problems in making counterfactual claims about mental events, which raise doubts about the usefulness of the counterfactual test in general.

The type-type reductive identity of the mental to the physical was once the dominant position in the mental causation debate. In time this consensus was overturned, largely due to its inability to handle the problem of multiple realizability. In its place a nonreductive position emerged which often included an adherence to functionalism. Functionalism construes mental properties as functional states of an organism, which in turn have specific physical realizers. This nonreductive form of functionalism, henceforth called role functionalism, has faced a number of criticisms itself. Chief among these is the concern that the realizer of the functional role is causally sufficient, so the role property does not make a contribution of its own. In this paper I argue that there is a way for unreduced functional properties to play a role after all. This is done by conceiving of functional properties as higher level functional properties of a macro system which determine that its realizers will play the roles that they play.

Stephen Yablo has recently argued for a novel solution to the mental causation problem: the mental is related to the physical as determinables are related to determinates; determinables are not causal rivals with their determinates; so the mental and the physical are not causal rivals. Despite its attractions the suggestion seems hard to accept. In this paper I develop the idea that mental properties and physical properties are not causal rivals. Start with property dualism, supervenience, multiple realizability, and the claim that no more than one supervenience base for a mental property can be had by a single instance of the mental property. Then a probabilistic account of causation will be unable to certify either mental properties or physical properties as causal factors for effect types. I suggest that this shows that we should not count mental properties as causal rivals with physical properties.