Online research in philosophy

This paper is about a puzzle which lies at the heart of contemporary physicalist theories of mind. On the one hand, the original motivation for physicalism was the need to explain the place of mental causation in the physical world. On the other hand, physicalists have recently come to see the explanation of mental causation as one of their major problems. But how can this be? I-low can it be that physicalist theories still have a problem explaining something which their physicalism was intended to explain in the first place? lf physicalism is meant to be an explanation of mental causation, then why should it still face the problem of mental causation? Disentagling this puzzle will cast light both on the recent mental causation debate and on physicalism itself. We can make a broad distinction between those forms of physicalism which identify mental and physical items and those which claim that there is some weaker relation of ’constitution’ between the mental and the physical. This latter view is now the orthodox version of physicalism. I shall argue that the problem of mental causation is only a problem for this orthodox physicalism, and not for identity theories. ln itself, this is not a particularly unusual claim. But I shall also argue that the real lesson of the mental causation debate is that orthodox physicalism is either unstable or unmotivated. It is unstable because (unlike the identity theories) it cannot reconcile mental causation with its other physicalist assumptions. It is unmotivated because in attempting to solve this mental causation problem, orthodox physicalism typically abandons one (or more) of the assumptions which form part of the original motivation for physicalism. To establish this, I need to explain (a) the nature of the arguments for physicalism, (b) the problem of mental causation, and (c) the standard solutions to the problem. These three tasks will form the main substance of this paper. But first I need to make some preliminary remarks about physicalism..

The anti-reductionist who wants to preserve the causal efficacy of mental phenomena faces several problems in regard to mental causation, i.e. mental events which cause other events, arising from her desire to accept the ontological primacy of the physical and at the same time save the special character of the mental. Psychology tries to persuade us of the former, appealing thereby to the results of experiments carried out in neurology; the latter is, however, deeply rooted in our everyday actions and beliefs and despite the constant opposition of science still very much alive. Difficulties, however, arise from a combination of two claims that are widely accepted in philosophy of mind, namely, physical monism and mental realism, the acceptance of which leads us to the greatest problem of mental causation: the problem of causal exclusion. Since physical causes alone are always sufficient for physical effects mental properties are excluded from causal explanations of our behaviour, which makes them “epiphenomenal”. The article introduces Van Gulick’s solution to the exclusion problem which tries to prove that physical properties, in contrast to mental properties, do not have as much of a privileged status with respect to event causation as usually ascribed. Therefore, it makes no sense to say that physical properties are causally relevant whereas mental properties are not. This is followed by my objection to his argument for levelling mental and physical properties with respect to causation of events. I try to show that Van Gulick’s argument rests on a premise that no serious physicalist can accept.

The paper argues that mental causation can be explained from the sufficiency of counterfactual dependence for causation together with relatively weak assumptions about the metaphysics of mind. If a physical event counterfactually depends on an earlier physical event, it also counterfactually depends on, and hence is caused by, a mental event that correlates with (or supervenes on) this earlier physical event, provided that this correlation (or supervenience) is sufficiently modally robust. This account of mental causation is consistent with the overdetermination of physical events by mental events and other physical events, but does not entail it.

Sydney Shoemaker has proposed a new definition of `realization’ and used it to try to explain how mental events can be causes within the framework of a non-reductive physicalism. I argue that it is not actually his notion of realization that is doing the work in his account of mental causation, but rather the assumption that certain physical properties entail mental properties that do not entail them. I also point out how his account relies on certain other controversial assumptions, including analytical filler-functionalism for mental properties, and the assumption that causes must be proportional to their effects. I conclude by pointing out that Shoemaker has provided no explanation of why, on his view, certain physical properties entail mental properties.

Over the past few decades, Jaegwon Kim has argued that non-reductive physicalism is an inherently unstable position. In his view, the most serious problem is that non-reductive physicalism leads to type epiphenomenalism—the causal inefficacy of mental properties. Kim suggests that we can salvage mental causation by endorsing functional reduction. Given the fact that Kim’s goal in formulating functional reduction is to provide a robust account of mental causation it would be surprising if his position implies eliminativism about mental properties or leads to a view that is similar to one of the versions of non-reductive physicalism that he criticizes. We will show that depending on how certain key claims are interpreted, there are reasons for thinking functional reduction has these implications, in which case either Kim fails to provide a robust account of mental causation or there is reason to suspect that some of his criticisms of non-reductive physicalism are misguided.

Orthodox physicalism has a problem with mental causation. If physics is complete and mental events are not identical to physical events (as multiple-realisation arguments imply) it seems as though there is no causal work for the mental to do. This paper examines some recent attempts to overcome this problem by analysing causation in terms of counterfactuals or conditional probabilities. It is argued that these solutions cannot simultaneously capture the force of the completeness of physics and make room for mental causation.

Over the past few decades, Jaegwon Kim has argued that non-reductive physicalism is an inherently unstable position. In his view, the most serious problem is that non-reductive physicalism leads to type epiphenomenalism—the causal inefficacy of mental properties. Kim suggests that we can salvage mental causation by endorsing functional reduction. Given the fact that Kim’s goal in formulating functional reduction is to provide a robust account of mental causation it would be surprising if his position implies eliminativism about mental properties or leads to a view that is similar to one of the versions of non-reductive physicalism that he criticizes. We will show that depending on how certain key claims are interpreted, there are reasons for thinking functional reduction has these implications, in which case either Kim fails to provide a robust account of mental causation or there is reason to suspect that some of his criticisms of non-reductive physicalism are misguided.

This paper is an attempt to understand the content of, and motivation for, a popular form of physicalism, which I call ‘non-reductive physicalism’. Non-reductive physicalism claims although the mind is physical (in some sense), mental properties are nonetheless not identical to (or reducible to) physical properties. This suggests that mental properties are, in earlier terminology, ‘emergent properties’ of physical entities. Yet many non-reductive physicalists have denied this. In what follows, I examine their denial, and I argue that on a plausible understanding of what ‘emergent’ means, the denial is indefensible: non-reductive physicalism is committed to mental properties being emergent properties. It follows that the problems for emergentism—especially the problems of mental causation—are also problems for non-reductive physicalism, and they are problems for the same reason.

This paper is about the causal exclusion argument against non-reductive physicalism. Many philosophers think that this argument poses a serious problem for non-reductive theories of the mind — some think that it is decisive against them. In the first part I will outline non-reductive physicalism and the exclusion argument. Then I will distinguish between three versions of the argument that address three different versions of non-reductive physicalism. According to the first, the relation between mental and physical events is token-identity. According to the second, mental events are distinct from physical events, but the latter metaphysically include and determine the former. And on the third version, mental and physical events are entirely distinct. I will argue that the causal exclusion argument is not decisive against non-reductive physicalism in any of the three versions. According to non-reductive physicalism, mental events are dependent on physical events. Causal exclusion and overdetermination, however, requires distinct and independent causes. I will argue that the burden of proof lies with the opponents of non-reductive physicalism, who have to explain how metaphysically dependent events can possibly overdetermine an effect or exclude each other from being causally efficacious.

Consider the following dilemma for non-reductive physicalism. If mental events cause physical events, they merely overdetermine their effects, given the causal closure of the physical. And if mental events cause only other mental events, they do not make the kind of difference we want them to. This dilemma can be avoided once the dichotomy between physical and mental events is dropped. Mental events make a real difference if they cause actions. But actions, I will argue, are neither mental nor physical events. Actions are realized by physical events, but they are not type-identical with them. This gives us non-reductive physicalism without downward causation. The tenability of such a view has been questioned. Jaegwon Kim, in particular, has argued that every version of non-reductive physicalism is committed to downward causation. But the nature action, I will argue, allows us to avoid this commitment.