Online research in philosophy

Abstract Substance dualism is widely rejected by philosophers of mind, but many continue to accept some form of property dualism. The assumption here is that one can consistently believe that (1) mental properties are not physical properties, while denying that (2) mental particulars are not physical particulars. But is this assumption true? This paper considers several analyses of what makes something a physical particular (as opposed to a non-physical particular), and it is argued that on any plausible analysis, accepting (1) requires accepting (2) as well.

The enduring metaphysical question about minds and mental phenomena concerns their nature. At least since Descartes this question—the mind-body problem—has been understood in terms of the viability or necessity of mind-body dualism, the thesis that minds and bodies are essentially distinct kinds of substance. Assuming that the nonmental (‘body’) portions of the world are constituted of physical stuff, the remaining question is: Are minds or mental phenomena essentially distinct non-physical substances, or phenomena that essentially involve such distinct kinds of substances? By the middle of the Twentieth Century there was broad philosophical and scientific consensus that the answer to this classical question about minds is negative: Minds and mental phenomena are not essentially distinct substances, nor are they phenomena that essentially involve distinct kinds of substances. There are at least two broad trends and one specific argument that lead to this conclusion. One trend is the decreasing influence of specifically theological arguments and commitments in philosophical argumentation, so that religious belief in immortal souls was no longer given much weight in the ontology of mind. The second trend, perhaps related to the first, is the increased demand that metaphysical theories bear explanatory fruits, so that the postulation of an immaterial and essentially mental substance appears to be a abdication from explanatory duties rather than a useful proposal. The argument, known to Descartes from the very beginning, is that there has never been an adequate account of 1 how two essentially distinct and incompatible substances could causally interact.1 Descartes’ solution was inadequate and brute, and his followers struggled with the problem—leading to Leibniz’s parallelism and Malebranche’s occasionalism, among other views. The problem of mental causation, then, is the central difficulty that underines substance dualism.2 The negative answer on the question of substance dualism, however, only increases the pressure for some monistic account of the nature of minds..

EVENTS CONSIST IN THE INSTANTIATION OF PROPERTIES IN SUBSTANCES. TWO WORDS WHICH RIGIDLY DESIGNATE PROPERTIES, PICK OUT THE SAME PROPERTIES, NOT JUST BECAUSE THE TWO PROPERTIES HAVE THE SAME CAUSES OR EFFECTS, BUT IF AND ONLY IF THE WORDS MEAN THE SAME. IT FOLLOWS THAT HAVING A RED AFTER IMAGE AND HAVING C-FIBRES FIRE ARE DIFFERENT PROPERTIES. ALTHOUGH THE INSTANTIATION OF TWO DIFFERENT PROPERTIES IN A SUBSTANCE MAY CONSTITUTE THE SAME EVENT, THAT WILL BE SO ONLY IF (IN GOLDMAN’S TERMINOLOGY) THE INSTANTIATION OF THE ONE LEVEL-GENERATES THE INSTANTIATION OF THE OTHER. THIS DOES NOT HOLD IN THE CASE OF MENTAL AND BRAIN EVENTS.

Events are the instantiations of properties in substances at times. A full history of the world must include, as well as physical events, mental events (ones to which the substance involved has privileged access) and mental substances (ones to the existence of which the substance has privileged access), and, among the latter, pure mental substances (ones which do not include a physical substance as an essential part). Humans are pure mental substances. An argument for this is that it seems conceivable that I could exist without my body. An objection to this argument is that ’I’ refers to my body, and so what seems conceivable is not metaphysically possible. My response to this objection is that ’I’ is an informative designator and so necessarily we know to what it refers, and it does not refer to my body.

Functionalism in the philosophy of mind rests on the claim that mental states are multiply realizable; mental states can be realized by or instantiated in a variety of distinct physical structures. To see them as multiply realizable we take mental states as causal roles rather than particular physical structures. As such, functionalism can be contrasted with metaphysical accounts which treat mental states as instances of a mental substance. Instead of puzzling over the relationship between mental and physical kinds, functionalists understand our talk of minds as a way of describing the functions of bodies. The attraction of a functionalist position is obvious. It seems to solve the traditional problem of mind-body dualism, while simultaneously reconciling the apparent irreducibility of psychological discourse with a broadly physicalistic or materialistic ontology.

Hard materialism claims that the only events are physical events, involving the instantiation of physical properties in physical substances. This however omits all the mental events to which we have privileged access. Soft materialism claims that the only events are physical events and mental events involving the instantiation of mental properties in physical substances. But a list of such events would not tell us which persons had which bodies. Only dualism, which holds that the essential part of each person is a mental substance, a soul, enables us to say which person occupies which body, and so to give a full description of the world.

Dualism is the view that mental phenomena are, in some respect, nonphysical. The best-known version is due to Descartes, and holds that the mind is a nonphysical substance. Descartes argued that, because minds have no spatial properties and physical reality is essentially extended in space, minds are wholly nonphysical. Every human being is accordingly a composite of two objects: a physical body, and a nonphysical object that is that human being's mind. On a weaker version of dualism, which contemporary thinkers find more acceptable, human beings are physical substances but have mental properties, and those properties aren't physical. This view is known as property dualism, or the dual-aspect theory.

The mind-body problem is the problem of explaining how our mental states, events and processes—like beliefs, actions and thinking—are related to the physical states, events and processes in our bodies. A question of the form, ‘how is A related to B?’ does not by itself pose a philosophical problem. To pose such a problem, there has to be something about A and B which makes the relation between them seem problematic. Many features of mind and body have been cited as responsible for our sense of the problem. Here I will concentrate on two: the fact that mind and body seem to interact causally, and the distinctive features of consciousness. A long tradition in philosophy has held, with René Descartes, that the mind must be a non-bodily entity: a soul or mental substance. This thesis is called ‘substance dualism’ (or ‘Cartesian dualism’) because it says that there are two kinds of substance in the world, mental and physical or material. One reason for believing this is the belief that the soul, unlike the body, is immortal. Another reason for believing it is that we have free will, and this seems to require that the mind is a non-physical thing, since all physical things are subject to the laws of nature. To say that the mind (or soul) is a mental substance is not to say that the mind is made up of some non-physical kind of stuff or material. The use of the term ‘substance’ is rather the traditional philosophical use: a substance is an entity which has properties and persists through change in its properties. A tiger, for instance, is a substance, whereas a hurricane is not. To say that there are mental substances— individual minds or souls—is to say that there are objects which are non-material or non-physical, and these objects can exist independently of physical objects, like a person’s body. These objects, if they exist, are not made of non-physical ‘stuff’: they are not made of ‘stuff’ at all..

Worries about mental causation are prominent in contemporary discussions of the mind and human agency. Originally, the problem of mental causation was that of understanding how a mental substance (thought to be immaterial) could interact with a material substance, a body. Most philosophers nowadays repudiate immaterial minds, but the problem of mental causation has not gone away. Instead, focus has shifted to mental properties. How could mental properties be causally relevant to bodily behavior? How could something mental qua mental cause what it does? After looking at the traditional Problem of Interaction, we survey various versions of the property-based problem and look at proposed solutions to them.

Physicalist epiphenomenalism is the conjunction of the doctrine that tokens of mental events are tokens of physical events and the doctrine that mental events do not exert causal powers by virtue of falling under mental types. The purpose of the paper is to show that physicalist epiphenomenalism, contrary to what many have thought, is not subject to the objections that have been raised against classic epiphenomenalism. This is argued with respect to five such objections: that introspection shows that our mental properties are causally efficacious; that concrete existents and their properties necessarily possess causal powers; that the explanatory and predictive success of psychology implies that psychological properties exist and are causally efficacious; that epiphenomenalism cannot deal with the other minds problem, and that it is unlikely that our mentality does not endow us with evolutionary advantages and therefore it is unlikely that mental properties are not causally efficacious.