The philosophical Direction of Physicalism - Essay Example

Why is Multiple Realisability a Problem for Type Identity Theory? Introduction Physicalist philosophers attempt to prove that all mental eventsare physical, and that dualism is therefore false. There are several varieties of physicalism: some more open to criticism than others. Type identity theory is a variety of physicalism which states that mental events are identical with physical ones (Warburton, 2004: 134). That is, when a person experiences something like pain, it is exactly reflected by a corresponding neurological state in the brain, such as the interaction of certain neurons, axons, etc. From this perspective, the mind is the brain, they are identical, and this constitutes the type identity theory (Philosphy Online 1, 2008) Type-type identity theories maintain that every type of mental state can be identified with some type of physical state. In contemporary philosophy of mind, type-type identity theories have been called into question on the grounds that types of mental state are plausibly, multiply realisable. The multiple realisability of mental state types states that two people exemplifying exactly the same mental state types can differ in respect to the physical state types which they exemplify. More specifically, a person’s mental state types at any given time supervene upon that person’s brain-state types at that time (Lowe, 2000: 49). This paper proposes to determine why multiple realisability is a problem for type identity theory. Discussion Functionalists in philosophy of mind traditionally raise two main arguments against the type identity theory. The first is that psychological states are multiply realisable, so that there are no one-to-one mapping of psychological states onto neural states. Secondly, the most that evidence could establish is the correlation of psychological and neural states, not their identity (Bechtel & McCauley, 1999: 67). Physicalism is the view that mental events can be completely explained in terms of physical ones, especially events in the brain. In contrast to mind/ body dualism which states that there are two basic sorts of substance, physicalism views that there is just one basic sort of substance: the physical. An advantage of physicalism over dualism is that it suggests a programme for the scientific study of the mind. In theory at least, it should be possible to give an entirely physical description of any mental event (Warburton, 2004: 134). The concept of dualism gives rise to all sorts of problems. Whether it is possible for mind and body to interact, since they are composed of different substances, how it is possible to know mental stuff exists, when it is known to be immaterial, hence without quantity, weight, size, or any other dimensions. As a result of these problems, some philosphers have argued that the dualist account of mind is unnecessarily complicated, and by adopting a materialist view, it is possible to solve the problems that it presents (Philosophy Online 2, 2008). Embracing type identity may mean that philosophers have to pay a price that they may not be willing to pay. Sometimes it is claimed that type identity excludes the multiple realisability of mental characteristics. In supposing that states of mind are neurological states, that mental characteristics are brain characteristics, the possibility of discovering conscious intelligent agents whose biology differed radically from ours, is excluded. Apparent counterexamples to type identity are creatures on earth to which we unhesitatingly ascribe a range of mental characteristics, differ biologically from us in several important respects. Many materialist minded philosophers have rejected type identity when compelled to choose between the multiple realisability of mental characteristics and type identity (Heil, 1992: 133). A problem for identity theory is the possibility that other species feel pain. Whether these species are real ones such as fish or insects, or hypothetical such as aliens from another planet, the problem is the same. These species may have different physical processes for registering pain, hence it is difficult to assume that such an experience is identical with only a certain brain state. The two options here are either to assume that such creatures do not have similar experiences as humans, or to admit that such conscious experiences as pain are multiply realisable. Multiply realisable means that in theory a mind may depend on vastly different physical mechanisms (Philosophy Online 3, 2008). Philosophers sometimes express the perspective that the prospect of multiple realisability automatically rules out type identities. It is in the nature of properties, however, that they are inevitably multiply realisable. If a given property P can be exemplified by objects of different sorts, objects possessing distinct properties, then P is, in one clear sense, multiply realisable. Regarded in this light, most properties can be multiply realisable (Heil, 1992: 134). Some advantages of type identity theory are that: it provides a solution to the problems of other minds. Having a type of neural state automatically implies having a type of mental state, so other minds are readily identifiable and can be studied. Also, this theory confers a scientific methodology for investigating mentality. To know about the mind, it would be essential to determine which types of neural states and mental states correlate with each other. The type identity theory also fits with the causal theory of the mind, if it were taken as being the correct analysis of mental states. On the other hand, the objections to type identity theory are that: although humans are able to learn about their mental states through introspection, they cannot learn about their neurophysiology through introspection. Hence, mental states cannot be type identical to neural states (Carter, 2007: 38-39). There is little agreement among philosophers about the criteria of property or type identity. However, there are prima facie grounds for favouring supervenience over identity in the mental/ physical case, One reason is the apparent multiple realisability of mental characteristics. Most mental characteristics are capable of being instantiated in a wide range of physical media such as computers. Also, despite large differences in underlying physiology across species, mental states are ascribed to them. However, even within the human species, it is unlikely that particular mental characteristics are invariably realised in identical neural structures (Heil, 1992: 64). Type identity theory needs to denote precisely what must be shared by neural states in order for them to qualify as being of the same type. Further objection to the type-identity claim is difficult to answer by the type identity theory. A person who suffers neural damage, loses all memory of familiar persons, objects and surrouindings. However, they are able to relearn everything and recover the mental capacities to understand the concepts that they lost, despite the fact that the neural substrate that supported these functions is irreparably damaged. Earlier mental state x meant being in the neural state x; after relearning the lost mental functions, however, mental state x meant totally different neural state y. This ability of parts of the brain to carry out functions that are normally undertaken by quite distinct parts of the brain is termed neural plasticity. The multiple realisability of mental states as demonstrated above, thus refutes the type identity theory. Further, the theory is against the possibility of non-human minds and the artificial intelligence in computers (Carter, 2007: 40-41). Thus multiple realisability is found to be a problem for type identity theory. Conclusion This paper has highlighted why multiple realisability is a problem for type-identity theory. The key element underlying multiple realisability objection is the assumption that: looking across species will yield type differences in brains despite the type identities of mental states. There is apparent heterogeneity of the mental domain itself. The heuristic identity theory proposes that identity claims between psychological processes and neural mechanisms are advanced as heuristics that serve to guide future research (Bechtel & McCauley, 1999: 71). References Bechtel, W. & McCauley, R.N. 1999. Heuristic identity theory: the mind-body problem against the background of research strategies in cognitive cognitive neuroscience. In: M. Hahn & S.C. Stoness (Eds.). Proceedings of the 21st Annual Conference of the cognitive science, New Jersey: Lawrence Erlbaum. Carter, M. 2007. Minds and computers. Edinburgh: Edinburgh University Press. Heil, J. 1992. The nature of true minds. The United Kingdom: Cambridge University Press. Lowe, E.J. 2000. An introduction to the philosophy of mind. The United Kingdom: Cambridge University Press. Philosophy Online 1. 2008. What is identity theory? Philosophy of Mind. Retrieved on 10th November, 2008 from: http://www.philosophyonline.co.uk/pom/pom_identity_what.htm Philosophy Online 2. 2008. Introduction. Philosophy of Mind. Retrieved on 10th November, 2008 from: http://www.philosophyonline.co.uk/pom/pom_identity_introduction.htm Philosophy Online 3. 2008. Multiple realisability. Philosophy of Mind. Retrieved on 10th November, 2008 from: http://www.philosophyonline.co.uk/pom/pom_identity_multiple_realisability.htm Warburton, N. 2004. Philosophy. The United Kingdom: Routledge. Read More