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.

Is there a problem of causal exclusion between micro- and macro-level physical properties? I argue (following Kim) that the sorts of properties thatin fact are in competition are macro properties, viz., the property of a (macro-) system of `having such-and-such macro properties'' (call this a `macro-structural property'') and the property of the same system of `being constituted by such-and-such a micro-structure'' (call this a `micro-structural property''). I show that there are cases where, for lack of reducibility, there is a prima facie intra-level causal competition between the two kinds of properties. The problem can be resolved without giving up on the causal efficacy of the macro-structural properties if we understandinstances of macro-structural properties to be parts ofmicro-structural property instances. The parthood relation between both kinds of property instances can bemapped onto the way physical theory deals with the relation of their descriptionsin the framework of perturbation theory. The application of this framework to theproblem of emergent properties is discussed.

Jaegwon Kim’s exclusion argument is a general ontological argument, applicable to any properties deemed supervenient on a microproperty basis, including biological properties. It implies that the causal power of any higher-level property must be reducible to the subset of the causal powers of its lower-level properties. Moreover, as Kim’s recent version of the argument indicates, a higher-level property can be causally efficient only to the extent of the efficiency of its micro-basis. In response, I argue that the ontology that aims to capture experimentally based explanations of metabolic control systems and morphogenetic systems must involve causally relevant contextual properties. Such an ontology challenges the exclusiveness of micro-based causal efficiency that grounds Kim’s reductionism, since configurations themselves are inherently causally efficient constituents. I anticipate and respond to the reductionist’s objection that the nonreductionist ontology’s account of causes and inter-level causal relations is incoherent. I also argue that such an ontology is not open to Kim’s overdetermination objection.

We have a familiar idea of levels of description or levels of theory in science: microphysics, atomic physics, chemistry, biology, psychology, and the various social sciences. It is clear that philosophers - such as Terry Horgan - who want to be nonreductive materialists with regard to the mental must hold that this is not mere description; there must be genuine higher-level causes, and hence, genuine higher-level properties, in particular mental properties and causes. But there appears to be a deep problem concerning mental causes. The (micro-) physical world is causally closed. Mental states are - or depend on or are realized by - physical states. It seems, then, that the physical state on which a mental state depends will be responsible for any alleged effects of the mental state. There will be no room for mental causation. And if properties exist insofar at they have a causal role, there will be no room for mental properties either. Many philosophers - Horgan included - have seen this problem of the "causalexclusion" ofthe mental as a specialcase of a general problem:the exclusion of higher-level causes by the causal closure of microphysics. Suppose one higher-level state, H1 leads to another higher-level state, H2. H1 is realized by some base level state, B1, which leads to a base-level state, B2, which in turn realizes H2. All of the casual work, so to speak, takes place at the base level. There is no room for any genuine causal connection between H1, as such, and H2, as such. I argue that there is no problem about higher-order causation in general. There are genuine, unsurprising higher-level causes and properties. A ball roles, for example, or breaks a window. If there is a problem of exclusion regarding putative mental causes, it is not an instance of a general exclusion problem, but is sui generis, and mental causation remains mysterious.

Two ways are considered of formulating a version of retentive physicalism, the view that in some important sense everything is physical, even though there do exist properties, e.g. higher-level scientific ones, which cannot be type-identified with physical properties. The first way makes use of disjunction, but is rejected on the grounds that the results yield claims that are either false or insufficiently materialist. The second way, realisation physicalism, appeals to the correlative notions of a functional property and its realisation, and states, roughly, that any actual property whatsoever is either itself a physical property or else is, ultimately, realised by instances of physical properties. Realisation physicalism is distinctive since it makes no claims of identity whatsoever, and involves no appeal to the dubious concept of supervenience. After an attempt to formulate realisation physicalism more precisely, I explore a way in which, in principle, we could obtain evidence of its truth.

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..

The systems studied in the special sciences are often said to be causally autonomous, in the sense that their higher-level properties have causal powers that are independent of those of their more basic physical properties. This view was espoused by the British emergentists, who claimed that systems achieving a certain level of organizational complexity have distinctive causal powers that emerge from their constituent elements but do not derive from them.2 More recently, non-reductive physicalists have espoused a similar view about the causal autonomy of specialscience properties. They argue that since these properties can typically have multiple physical realizations, they are not identical to physical properties, and further they possess causal powers that differ from those of their physical realizers.3 Despite the orthodoxy of this view, it is hard to find a clear exposition of its meaning or a defence of it in terms of a well-motivated account of causation. In this paper, we aim to address this gap in the literature by clarifying what is implied by the doctrine of the causal autonomy of special-science properties and by defending the doctrine using a prominent theory of causation from the philosophy of science. The theory of causation we employ is a simplified version of an “interventionist” theory advanced by James Woodward (2003, forthcoming a, b), according to which a cause makes a counterfactual difference to its effects. In terms of this theory, it is possible to show that a special-science property can make a difference to some effect while the physical property that realizes it does not. Although other philosophers have also used counterfactual analyses of causation to argue for the causal autonomy of special-science properties,4 the theory of causation we employ is able to establish this with an unprecedented level of precision..

Jaegwon Kim’s causal exclusion argument says that if all physical effects have sufficient physical causes, and no physical effects are caused twice over by distinct physical and mental causes, there cannot be any irreducible mental causes. In addition, Kim has argued that the nonreductive physicalist must give up completeness, and embrace the possibility of downward causation. This paper argues first that this extra argument relies on a principle of property individuation, which the nonreductive physicalist need not accept, and second that once we get clear on overdetermination, there is a way to reject the exclusion principle upon which the causal exclusion argument depends, but third that this should not lead to the belief that mental causation is easily accounted for in terms of counterfactual dependencies.

In this paper I develop a novel response to the exclusion problem. I argue that the nature of the events in the causally complete physical domain raises the “problem of many causes”: there will typically be countless simultaneous low-level physical events in that domain that are causally sufficient for any given high-level physical event (like a window breaking or an arm raising). This shows that even reductive physicalists must admit that the version of the exclusion principle used to pose the exclusion problem against non-reductive physicalism is too strong. The burden is on proponents of the exclusion problem to provide a reason to think that any qualifications placed on the exclusion principle will solve the problem of many causes while ruling out causation by irreducible mental events.