Online research in philosophy

Nonreductive physicalism provides an appealing solution to the nature of mental properties. But its success as a theory of mental properties has been called into doubt by claims that it cannot adequately handle the problems of mental causation, as it leads either to epiphenomenalism or to thoroughgoing overdetermination. I argue that these apparent problems for the nonreductivist are based in fundamental confusion about causation and explanation. I distinguish two different types of explanation and two different relations to which they appeal: causation and determination. I argue that these types of explanation do not compete with one another, nor do these relations jointly result in overdetermination. In closing I develop a nonreductivist solution to mental causation which avoids both the hazards of epiphenomenalism and of overdetermination and so demonstrates a way to save nonreductive physicalism from the problems of mental causation.

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.

Kim argues that we can never have more than one complete and independent explanation for a single event. The existence of both mental and physical explanations for behavior would seem to violate this principle. We can avoid violating it only if we suppose that mental causal relationships supervene on physical causal relationships. I argue that although his solution is attractive in many respects, it will not do as it stands. I propose an alternate understanding of supervenient causation which preserves the advantages of Kim's account while avoiding the problems. My analysis involves appeal to counterfactuals. Any counterfactual analysis must confront the problem that mental states appear to be screened off from causal relevance by physical states. I argue that screening off is not a problem, because cases in which mental states appear to be screened off are cases in which background conditions are not held constant.

The paper argues against systematic overdetermination being an acceptable solution to the problem of mental causation within a Humean counterfactual theory of causation. The truth-makers of the counterfactuals in question include laws of nature, and there are laws that support physical to physical counterfactuals, but no laws in the same sense that support mental to physical counterfactuals.

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 Exclusion Problem (EP) for mental causation suggests that there is a tension between the claim that the mental causes physical effects, and the claim that the mental does not overdetermine its physical effects. In response, Karen Bennett (2008, 2003) puts forward an extra necessary condition for overdetermination: if one candidate cause were to occur but the other were not to occur, the effect would still occur. She thus denies one of the assumptions of EP, the assumption that if an effect has two sufficient causes, it is overdetermined. If sound, her argument does two things: it solves EP, and it shows how to use counterfactuals in order to make the notion of overdetermination precise. However, the argument is not sound.

It seems to be generally accepted that (a) counterfactual conditionals are to be analysed in terms of possible worlds and inter-world relations of similarity and (b) causation is conceptually prior to counterfactuals. I argue here that both (a) and (b) are false. The argument against (a) is not a general metaphysical or epistemological one but simply that, structurally speaking, possible worlds theories are wrong: this is revealed when we try to extend them to cover the case of probabilistic counterfactuals. Indeed a type of counterfactual probability exists which cannot be expressed in possible worlds terms at all. The argument against (b) emerges when we look at the form of an adequate account of both probabilistic and non-probabilistic counterfactuals. I do this by sketching and defending an approach to counterfactuals that, first, invoke a generalized notion of cause as primitive and, secondly, is algorithmic in form: counterfactuals are evaluated algorithmically in terms of other counterfactuals, without vicious circularity. Structures like possible worlds do not play a role either in general truth-conditions or in evaluation. They are simply the wrong sorts of structures.

In this paper I wish to argue that counterfactual analyses of causation are inadequate. I believe the counterfactuals that are involved in counterfactual analyses of causation are often false, and thus the theories do not provide an adequate account of causation. This is demonstrated by the presentation of a counterexample to the counterfactual analyses of causation. I then present a unified theory of causation that is based upon probability and counterfactuals. This theory accounts for both deterministic and indeterministic causation, and is not subject to many of the traditional problems facing theories of causation.

If we seek to analyse causation in terms of counterfactual conditionals then we must assume that there is a class of counterfactuals whose members (i) are all and only those we need to support our judgements of causation, (ii) have truth-conditions specifiable without any irreducible appeal to causation. I argue that (i) and (ii) are unlikely to be met by any counterfactual analysis of causation. I demonstrate this by isolating a class of counterfactuals called non-projective counterfactuals, or NP-counterfactuals, and indicate how counterfactual analyses of causation must appeal to them to account for the correct causal judgements we make. I show that the truth-conditions of NP-counterfactuals are specifiable only by irreducible appeal to causation. A dilemma then holds: if counterfactual analyses of causation eschew appeal to NP-counterfactuals they are empirically inadequate, but if they appeal to NP-counterfactuals they are circular and thus conceptually inadequate.