Central State Materialism and Consciousness

Abstract

Central State Materialism is often referred to as 'the Identity theory'. This is confusing because Central State Materialism comprises two quite distinct component theses one of which is itself best called the Identity Thesis, i.e. the thesis that all conscious states are in fact identical with physical states. According to the Identity Thesis when someone has toothache the ache is identical with certain neurophysiological processes going on in the person's brain. The other component thesis of Central State Materialism may be called Mechanism, i.e. the thesis that all physical phenomena are completely determined in every aspect by (i) the relevant laws of nature and (2) the physical conditions which cause the phenomena. According to Mechanism our every physical movement, everything we say or do, is determined by the laws of physics, chemistry, etc., together with the state of our brain, sense organs, etc., and our current surroundings. Mechanism implies that the brain works in a distinctive way, namely, like a machine; but it says nothing about how the workings of the brain are related to consciousness, indeed, it says nothing whatever about consciousness. The Identity Thesis on the other hand says nothing about how the brain works; it just says that some of the brain's workings are as a matter of fact identical with conscious states (e.g. being pleased, being excited, hearing an unexpected noise, being dazzled by the sun). In short, Central State Materialism consists of two complementary theses: Mechanism-a theory about how the body works, and the Identity Thesis-a theory about how the body is related to the mind. (However, we shall see later that in the face of criticisms of Central State Materialism the Identity Thesis has to be interpreted more narrowly in such a way as logically to involve Mechanism, so that this version of the Identity Thesis is equivalent to Central State Materialism.) I shall argue that we have good reason to reject Central State Materialism. First I shall use a recent argument of Karl Popper's1 to show that Mechanism, unless combined with the Identity Thesis, does not square with the Darwinian theory of evolution. Next we shall examine Popper's attempt to show that Central State Materialism also clashes with Darwinism.