16. Four Materialist or Physicalist Positions

Three of the four views which I will classify here as "materialist" or "physicalist" (see section 3 above) admit the existence of mental processes, and especially of consciousness, but all four assert that the physical world — what I am calling "World 1" — is self-contained or closed. By this I mean that physical processes can be explained and understood, and must be explained and understood, entirely in terms of physical theories.

I call this the physicalist principle of the closedness of the physical World 1. It is of decisive importance, and I take it as the characteristic principle of physicalism or materialism.

I have earlier suggested that we are faced with a prima facie dualism or pluralism, with interaction between World 1 and World 2; moreover, I have suggested that by way of the mediation of World 2, World 3 can act upon World 1. By contrast, the physicalist principle of the closedness of World 1 either asserts that there is only a World 1 or implies that if there is anything like a World 2 or a World 3 it cannot act upon World 1: World 1 is self-contained or closed. This position is intrinsically convincing. Most physicists would be inclined to accept it without question. But is it true? And are we able, if we accept it, to provide an adequate alternative explanation of our prima facie dualism? In the present chapter, I will suggest that the theories produced by materialists to date are unsatisfactory, and that there is no reason to reject our prima facie view; a view that is inconsistent with the physicalist principle. (It might be added that, in my opinion, the openness of the physical world is needed to explain — rather than explain away — human freedom. See my [1973 (a)].)

In this introductory section I will distinguish the following four materialist or physicalist positions:

(1) Radical Materialism or Physicalism, or Radical Behaviourism. This is the view that conscious processes and mental processes do not exist: their existence can be "repudiated" (to use a term of W. V. Quine's).

I do not think that many materialists have held this view in the past (see section 56 below), for it stands in flagrant opposition to, or tries in the end to explain away, what to most of us appear as undeniable facts, such as (subjective) pain and suffering. The great classical systems of materialism, from the early Greek materialists to Hobbes and La Mettrie, are not "radical" in the sense of denying the existence of conscious or mental processes. Nor is the "dialectical materialism" of Marx and Lenin "radical" in this sense, or the behaviourism of most behaviourist psychologists.¹

Nevertheless, what I call radical materialism (or radical physicalism or radical behaviourism) is an important position which must not be neglected. First, because it is consistent in itself. Secondly, because it presents a very simple solution of the mind-body problem: the problem clearly disappears if there is no mind, but only body.² (Of course, the problem also disappears if we adopt a radical spiritualism or idealism, such as the phenomenalism of Berkeley or Mach, that denies the existence of matter.) Thirdly, because in the light of evolutionary theory, matter, and especially chemical processes, existed before mental processes existed. Current theories suggest that the evolution and the development of the body come before the evolution and the development of the mind; and they are the basis of the evolution and the development of the mind. Since this is so, it is understandable that, under the impact of contemporary science, we might perhaps become radical physicalists if we are strongly inclined towards monism and simplicity, and do not wish to accept a dualist or a pluralist view of things.

It is for reasons such as these that a radical physicalism or a radical behaviourism is accepted by some outstanding philosophers such as Quine ([1960], p.264; [1975], pp. 93ff.); and it is now often suggested by others that something very much like a radical physicalism or behaviourism will ultimately have to be accepted, perhaps because of the results of science or of philosophical analysis. Suggestions such as these, though not always unambiguous ones, can be found for example in the works of Ryle [1949], [1950] or of Wittgenstein [1953]; of Hilary Putnam [1960] or of J.J.C. Smart [1963]. Indeed one may perhaps say that, at the time of writing, radical materialism or behaviourism seems to be the view concerning the mind-body problem that is most fashionable among the younger generation of students of philosophy. Thus it has to be discussed.

My criticism of radical materialism or radical behaviourism will be along three lines. First, I will argue that, by denying the existence of consciousness, this view of the world simplifies cosmology — but it does so by omitting rather than by solving its greatest and most interesting riddle. Further, I will argue that a principle which many adopt as "scientific", and which speaks in favour of radical behaviourism, springs from a misunderstanding of the method of the natural sciences. And lastly I will argue that this view is false, and that it is refuted by experiment (although, of course, a refutation can always be evaded).²

(2) All the other views which I classify here as materialistic admit the existence of mental processes and, especially, of conscious processes: they admit what I call World 2. However, they also accept the fundamental principle of physicalism — the closedness of World 1.

The oldest of these views, panpsychism, goes back to the earliest Pre-socratics and to Campanella. It was elaborately presented in Spinoza's Ethics, and in Leibniz's Monadology.

Panpsychism is the view that all matter has an inside aspect which is a soul-like or a consciousness-like "quality". Thus for panpsychism, matter and mind run "parallel" like the outside and the inside aspects of an eggshell (Spinozistic parallelism). In non-living matter, the inside aspect may not be conscious: the soul-like precursor of consciousness may be described as "pre-psychical" or "proto-psychical". With the integration of atoms into giant molecules and living matter, memory-like effects emerge; and with the higher animals, consciousness emerges.

Panpsychism was defended in Britain especially by the mathematician and philosopher William Kingdon Clifford [1879], [1886], Clifford teaches (not unlike Leibniz's form of parallelism) that things in themselves are mind-stuff (pre-psychical or else psychical) but that, observed from the outside, they appear as matter.³

Panpsychism shares with radical materialism a certain simplicity of outlook. The universe is in both cases homogeneous and monistic. Their motto could well be: "There really is no new thing under the sun", which indicates an intellectually comfortable way of living — though not an intellectually very exciting one. But everything in the universe seems to fit very nicely once the radical materialistic view, or the panpsychistic view, is adopted.

(3) Epiphenomenalism may be interpreted as a modification of panpsychism, in which the "pan" element is dropped and the "psychism" is confined to those living things that seem to have a mind. Like panpsychism it is, in its usual form, a variety of parallelism; that is to say, of the view that mental processes run parallel with certain physical processes — say, because they are the inside and the outside views of some (unknown) third entity.

However, there may be forms of epiphenomenalism which are not parallelist: what I take to be essential in epiphenomenalism is the thesis that only the physical processes are causally relevant with respect to later physical processes, while the mental processes, though existing, are causally completely irrelevant.

(4) The identity theory, or the central state theory, is at present the most influential of the theories developed in response to the mind-body problem. It may be regarded as a modification of both panpsychism and epiphenomenalism. Like epiphenomenalism, it can be seen as panpsychism without the "pan". But as opposed to epiphenomenalism it takes mental facts as important and as causally effective. It asserts that there is some kind of "identity" between mental processes and certain brain processes: not an identity in the logical sense, but still an identity such as that between "the evening star" and "the morning star" which are alternative names for one and the same planet, Venus; though they also denote different appearances of the planet Venus. In one form of the identity theory, a form due to Schlick and Feigl, the mental processes are regarded (as by Leibniz) as things in themselves, known by acquaintance, from the inside, while our theories about brain processes — processes of which we know only by theoretical description — happen to describe the same things from the outside. In contrast to an epiphenomenalist, the identity theorist can say that mental processes interact with physical processes, for the mental processes simply are physical processes; or more precisely, special kinds of brain processes.

In section 10 above, I discussed, briefly, the example of a visit to the dentist, to illustrate the way in which physical states (World 1), our conscious awareness (World 2), and plans and institutions (World 3) are all involved in such actions. The character of our four materialistic theories may be illustrated by the way in which they would give an account of such an incident. It might involve, for example, our damaging a tooth, our developing a toothache, our 'phoning the dentist to make an appointment, and our subsequent visit to him in order to obtain treatment.

(1) Radical materialist interpretation: there are processes in my tooth leading to processes in my nervous system. Everything that happens consists of physical processes confined to World 1 (including my verbal behaviour — my uttering words on the telephone).

(2) Panpsychistic interpretation: there are the same physical processes as in (1), but there is also another side to the story. There is a "parallel" account (which various panpsychists may explain in different ways) which tells the story as it is experienced by us. Panpsychism tells us not only that our experience in some way "corresponds" to the physical explanation as given in (1), but that the apparently purely physical objects involved (such as the telephone) have also an "inner aspect", more or less similar to our own inner awareness.

(3) Epiphenomenalist interpretation: there are the same physical processes as in (1), and the rest of the story is not unlike (2). But there are the following differences from (2): (a) only the "animate" objects have "inner" or subjective experiences; (b) whereas in (2) it was suggested that we have two different but equally valid accounts, the epiphenomenalist not only gives priority to the physical account, but emphasizes that subjective experiences are causally redundant: my felt pain plays no causal role whatever in the story; it does not motivate my action.

(4) Identity theory: the same as in (1), but this time we can distinguish between those World 1 processes which are not identical with conscious experiences (World l_p: the subscript p stands for "purely physical") and those physical processes which are identical with experienced or conscious processes (World l_m: the subscript m stands for "mental"). The two parts of World 1 (that is to say, the sub-worlds \_p and l_m) can, of course, interact. Thus my pain (World 1 _m) acts upon my memory store and this makes me look up the telephone number. Everything happens as in the interactionist analysis (this is, I think, what makes this view attractive) only my World 2 (including subjective knowledge) is identified with World l_m, that is, with a part of World 1, and World 3 is identified with other parts of World 1: with instruments, or gadgets, such as the telephone directory or the telephone (or perhaps with brain processes: for the identity theorist abstract knowledge contents, which are the heart of my World 3, do not exist).

¹  Compare, on this, the remark about Marx on p. 102 of volume II of my Open Society [1966 (a)], and the remarks on the Stoics in footnotes 6 and 7 on p. 157 of my [1972 (a)].

² Some radical materialists do, however, take the problem seriously. See section 25 below.

²  See my [1959 (a)], sections 19-20.

³  Clifford mentions several German philosophers as precursors of his view. Thus, in ([1886], p.286) he refers to Kant's Critique of Pure Reason. Clifford refers to Rosenkranz's edition, which reprints the text of the first edition of the Critique; see note 1 to section 22 below. Clifford also mentions Wilhelm Wundt ([1880], volume II, pp. 460ff.) and Ernst Haeckel [1878]. Later representatives of panpsychism in Germany are Theodor Ziehen [1913], and Bernhard Rensch [1968], [1971], The identity theory of Moritz Schlick and Herbert Feigl shows a certain similarity to panpsychism, although they do not seem to discuss the evolutionary aspects of the problem, and therefore do not say that the "things in themselves", or the "qualitites", of non-living things are pre-psychical in character. (See also section 54 below.)