Online research in philosophy

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.

The basic form of the exclusion problem is by now very, very familiar. 2 Start with the claim that the physical realm is causally complete: every physical thing that happens has a sufficient physical cause. Add in the claim that the mental and the physical are distinct. Toss in some claims about overdetermination, give it a stir, and voilá—suddenly it looks as though the mental never causes anything, at least nothing physical. As it is often put, the physical does all the work, and there is nothing left for the mental to do.

In this paper I discuss a famous argument for physicalism – which some authors indeed regard as the only argument for it – the overdetermination argument. In fact it is an argument that does not establish that all the entities in the world are physical, but that all those events that enter into causal transactions with the physical world are physical. As mental events seem to cause changes in the physical world, the mind is one of those things that fall within the scope of the argument. Here I analyze one response to the overdetermination argument that has acquired some popularity lately, and which consists in saying that what mental events cause are not physical effects. I try to show that recent attempts to develop this response are not successful, but that there may be a coherent way of doing so. I also try to show that there seems to be a philosophical niche in which this way might fit.

A well-known ``overdetermination''argument aims to show that the possibility of mental causes of physical events in a causally closed physical world and the possibility of causally relevant mental properties are both problematic. In the first part of this paper, I extend an identity reply that has been given to the first problem to a property-instance account of causal relata. In the second, I argue that mental types are composed of physical types and, as a consequence, both mental and physical types may be causally relevant with respect to the same physical effect, contrary to the overdetermination argument. In further sections, I argue that mental types have causal powers, consider some objections and reject an alternative version of part-whole physicalism. Throughout I assume that causal relata are tropes and property types are classes of tropes.

In this paper I argue that the problem of mental causation can be solved by distinguishing between classificatory mental properties, like being a pain, and instances of those properties.Antireductive physicalism allows only that the former be irreducibly mental. Consequently, properties like being a pain cannot have causal commerce with the physical without violating causal closure. But instances of painfulness, according to the token identity thesis, are identical with various physical tokens and can therefore have causal efficacy in the physical world. Since we expect particular mental phenomena, not types or classes of mental phenomena to be involved in causal interactions, it is argued that antireductive physicalism can explain satisfactorily mental causation, despite the protests of Kim, Sosa, Honderich, and others. Being a mental state of a certain sort may have no causal efficacy, but the intentional and phenomenal properties of such states should, if my argument is correct.

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.

In our everyday discourse, we distinguish without fail between minds and bodies or between the mental and the physical. Yet, in philosophy there is a tendency to get rid of this divide. Roughly, the naturalist wants to reduce or to identify the mental with the physical in order to provide a unified basis for scientific research. The idealist, in contrast, sticks to the mental as a precondition of grasping the physical. The physical then tends to turn into mere mental representations. These attempts to overcome the divide, however, are not very promising. While the first tries to assimilate the mental to the physical, the second takes the opposite approach with the result that either the mental or the physical goes by the board. Fortunately, there is a third option: the realist maintains that the mental exists along with the physical.

Given some reasonable assumptions concerning the nature of mental causation, non-reductive physicalism faces the following dilemma. If mental events cause physical events, they merely overdetermine their effects (given the causal closure of the physical). 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 if we drop the dichotomy between physical and mental events. Mental events make a real difference if they cause actions. But actions are neither mental nor physical events. They 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 this view has been questioned. Jaegwon Kim, in particular, has argued that non-reductive physicalism is committed to downward causation. Appealing to the nature of actions, I will argue that this commitment can be avoided.

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.

Physicalism is the claim that that there is nothing in the world but the physical. Philosophers who defend physicalism have to confront a well-known dilemma, known as Hempel’s dilemma, concerning the definition of ‘the physical’: if ‘the physical’ is whatever current physics says there is, then physicalism is most probably false; but if ‘the physical’ is whatever the true theory of physics would say that there is, we have that physicalism is vacuous and runs the risk of becoming trivial. This article has two parts. The first, negative, part is devoted to developing a criticism of the so-called via negativa response to Hempel’s dilemma. In the second, more substantial, part, I propose to take the first horn of Hempel’s dilemma. However, I argue for a broad construal of ‘current physics’ and characterize ‘the physical’ accordingly. The virtues of the broad characterization of ‘the physical’ are: first, it makes physicalism less likely to be false; and second, it ties our understanding of ‘the physical’ to the reasons we have for believing in physicalism. That is, it fulfills the desideratum of construing our theses according to the reasons we have to believe in them.