Online research in philosophy

The paper sets out a new strategy for theory reduction by means of functional sub-types. This strategy is intended to get around the multiple realization objection. We use Kim's argument for token identity (ontological reductionism) based on the causal exclusion problem as starting point. We then extend ontological reductionism to epistemological reductionism (theory reduction). We show how one can distinguish within any functional type between functional sub-types. Each of these sub-types is coextensive with one type of realizer. By this means, a conservative theory reduction is in principle possible, despite multiple realization. We link this account with Nagelian reduction, as well as with Kim's functional reduction.

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.

In numerous papers Jaegwon Kim argues that nonreductive materialists (i.e., those philosophers who believe that there are no irreducible non-physical objects in the universe, and yet there are irreducible psychological properties which are indispensable in intentional psychological explanations) face two problems. One is that intentional mental properties are not causally relevant; the other is that explanations appealing to these properties are excluded by explanations appealing to physical, in particular, microphysical, properties.1 The first problem can be called the problem of epiphenomenalism. The second problem is what Kim calls the problem of explanatory/causal exclusion. Epiphenomenalism is not just a problem for nonreductive materialists, but a problem for psychology (as a science of psychological explanation), and for anyone who believes that our thought is the cause of our action. Kim argues that the exclusion problem, on the other hand, is especially a problem for nonreductive materialists. Nonreductive materialists typically buy into the principle of the causal closure of the physical domain, according to which "any physical event that has a cause at time t has a physical cause at t..... [I]f we trace the causal ancestry of a physical event, we need never go outside the physical domain." [Kim 1989b, p. 280] One cannot reject this principle unless one is willing to go back to Cartesian dualism. But the problem is, if all causation is done at the physical level, then there is no causal work left for mental kinds. If mental kinds do not play any causal role, then intentional psychological explanations that appeal to mental properties are not warranted. Therefore, Kim concludes, nonreductive materialism is an untenable position. Some nonreductionists (Davidson, Dretske, LePore & Loewer, Jackson & Pettit, for example) have tried to argue for the causal relevancy of mental properties from an..

Jaegwon Kim has recently[1] argued that a solution to the exclusion argument against the intelligibility of mental causation is to found if mental properties can be shown to be reducible to physical properties.

The importance of downward causation lies in showing that it shows that functional properties such as mental properties are real, although they cannot be reduced to physical properties. Kim rejects nonreductive physicalism, which includes leading functionalism, by eliminating downward causation, and thereby returns to reductionism. In this paper, I make a distinction between two aspects of function—functional meaning and functional structure and argue that functional meaning cannot be reduced to the physical level whereas functional structure can. On this basis, I further distinguish between the integer of the function, which includes the functional meaning and the functional structure, and the whole of the functional realization, and also among the strong, medial, and weak supervenience relations. So-called downward causation is indeed the relationship between the whole of the functional realization and its physical realizer, which is a whole-part relation instead of a relation between levels. As a result of understanding downward causation in this way and abandoning the principle of the causal closure of the physical world, Kim’s argument becomes invalid and nonreductive functionalism, justified.

In this paper I examine Jaegwon Kim’s view that emergent properties are irreducible to the base properties on which they supervene. Kim’s view assumes a model of ‘functional reduction’ which he claims to be substantially different from the traditional Nagelian model. I dispute this claim and argue that the two models are only superficially different, and that on either model, properly understood, it is possible to draw a distinction between a property’s being reductively identifiable with its base property and a property’s being reductively explainable in terms of it. I propose that we should take as the distinguishing feature of emergent properties that they be truly novel properties, i.e., ontologically distinct from the ‘base’ properties which they supervene on. This only requires that emergent properties cannot be reductively identified with their base properties, not that they cannot be reductively explained in terms of them. On this conception the set of emergent properties may well include mental properties as conceived by nonreductive physicalists.

The paper defends Functionalism against the charge that it would make mental properties inefficacious. It outlines two ways of formulating the doctrine that mental properties are Functional properties and shows that both allow mental properties to be efficacious. The first (Lewis) approach takes functional properties to be the occupants of causal roles. Block [1990] has argued that mental properties should not be characterized in this way because it would make them properties of the ?implementing science?, e. g. neuroscience. I show why this is not a problem. The second way of formulating the doctrine takes functional properties to be causal role properties. I claim that mental properties so understood would only be inefficacious if a law-centred rather than a property-centred approach is adopted to the introduction of efficacy into the world. I develop a property-centred account that explains how mental properties can be efficacacious without introducing systematic overdetermination. At the close, I provide a better characterization of the difference between these two approaches and offer an explanation as to why my way of resolving the problems has been missed.

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.

The view that special science properties are multiply realizable has been attacked in recent years by Shapiro, Bechtel and Mundale, Polger, and others. Focusing on psychological and neuroscientific properties, I argue that these attacks are unsuccessful. By drawing on interspecies physiological comparisons I show that diverse physical mechanisms can converge on common functional properties at multiple levels. This is illustrated with examples from the psychophysics and neuroscience of early vision. This convergence is compatible with the existence of general constraints on the evolution of cognitive systems, and does not involve any ad hoc typing of coarse-grained higher level properties. The mechanisms that realize these common higher level properties are really distinct by the criteria laid down by critics of multiple realizability. Finally, I present an account of how such functional properties might constitute special science kinds by playing a central explanatory role in a range of cognitive models. Behavioral science kinds in particular are the functionally defined constituents picked out by our most successful models of the multilevel systems and mechanisms that explain cognitive capacities.

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.