Online research in philosophy

The realization relation that allegedly holds between mental and physical properties plays a crucial role for so-called non-reductive physicalism because it is supposed to secure both the ontological autonomy of mental properties and, despite their irreducibility, their ability to make a causal difference to the course of the causally closed physical world. For a long time however, the nature of realization has largely been ignored in the philosophy of mind until a couple of years ago authors like Carl Gillett, Derk Pereboom, or Sydney Shoemaker proposed accounts according to which realization is understood against the background of the so-called ‘causal theory of properties’. At least partially, the hope was to solve the problem of mental causation, in particular the kind of causal exclusion reasoning made famous by Jaegwon Kim, in a way acceptable to non-reductive physicalists. The paper asks whether a proper explication of the realization relation can indeed help explain how physically realized mental properties can be causally efficacious in the causally closed physical world and argues for a negative answer: it is important for the non-reductive physicalist to understand what exactly the realization relation amounts to, but it does not solve the problem of mental causation.

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.

causal relevance, a three-place relation between event types, and circumstances, and argue for a logical independence condition on properties standing in the causal relevance relation relative to circumstances. In section 3, I apply these results to show that functionally defined states are not causally relevant to the output or state transitions in terms of which they are defined. In section 4, I extend this result to what that output in turn causes and to intervening mechanisms. In section 5, I examine the implications of this result for functional theories of mental states. In section 6, I distinguish between functional descriptions of properties and functional definitions of properties, and argue the former present no obstacle to mental states being causally relevant to behavior, but that this is so because they do not treat mental states as functional states. In section 7, I examine the nature of explanations that appeal to functional states or properties. section 8 identifies some difficulties that arise in thinking about specifically conscious mental states as functional states. section 9 is a brief conclusion.

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.

Emergent properties are intended to be genuine, natural higher level causally efficacious properties irreducible to physical ones. At the same time they are somehow dependent on or 'emergent from' complexes of physical properties, so that the doctrine of emergent properties is not supposed to be returned to dualism. The doctrine faces two challenges: (i) to explain precisely how it is that such properties emerge - what is emergence; (ii) to explain how they sidestep the exclusion problem - how it is that there is room for these properties to be causally efficacious, given the causal completeness of the physical. In this paper I explain how functional properties can meet both challenges.

In a recent paper, Bird (in: Groff (ed.) Revitalizing causality: Realism about causality in philosophy and social science, 2007 ) has argued that some higher-order properties—which he calls “evolved emergent properties”—can be considered causally efficacious in spite of exclusion arguments. I have previously argued in favour of a similar position. The basic argument is that selection processes do not take physical categorical properties into account. Rather, selection mechanisms are only tuned to what such properties can do, i.e., to their causal powers. This picture seems ultimately untenable in the light of further exclusion problems; but at the same time, it meets our explanatory demands. My purpose is therefore to show that there is a real antinomy with regard to evolved emergent properties. I develop a physicalist exclusion argument and then I go on to consider an argument that seems to establish that evolved emergent properties are causally efficacious, and propose a compatibilist solution. Finally, I very briefly consider what the proposed model may imply for the issue of mental causation.

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.

This paper argues that the non-reductive monist need not be concerned about the ‘problem’ of mental causation; one can accept both the irreducibility of mental properties to physical properties and the causal closure of the physical. More precisely, it is argued that instances of mental properties can be causally efficacious, and that there is no special barrier to seeing mental properties whose instances are causally efficacious as being causally relevant to the effects they help to bring about. It is then shown that the causal relevance of mental properties is consistent with there being no downward causation, so the dilemma of ‘epiphenomenalism or reduction’ can be avoided. Non-reductive monism lives on as a viable position in the philosophy of mind.

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.

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.