Functionalism As Levine indicates, from a functionalist viewpoint, the status of a mental state is not given by its internal constitution but by its function. For instance, a thought or a pain depends on its function or its role in the cognitive system. More precisely, functionalist theories take the identity of a mental state to be determined by its causal relations to sensory stimulations, other mental states, and behavior. (Levine 2004) Functionalism is a neutral approach between materialism and dualism. However, in general they are materialists: each mental state is identical to a neural state. Turing (Turing 1950) replaced the Can machines think? with Is it theoretically possible for a finite state digital computer, provided with a large but finite table of instructions, or program, to provide responses to questions that would fool an unknowing interrogator into thinking it is a human being? (Levine 2004) This is Turing test. For Turing, thoughts = internal states and verbal outputs Later - functionalism (Putnam 1960 1967). (Levine 2004) Functionalism had different trends: machine functionalism, psychofunctionalism and analytic functionalism. Their sources were early AI theories, empirical behaviorism, and logical behaviorism. (Levine 2004) (1) Machine Functionalism Against the identity theory- Putnam (1960, 1967) creatures without brains like Martians or silicon-based robots are not in the same mental states as us but they can share in principle- the same beliefs. (Clark 2001, p. 14) Within the framework created by logic and formal systems, Turing machines and computers we can say that the common thing among humans, Martians and robots is not the particular physical systems, not their behavior or internal organization but the abstract, formal organization of the system. (Clark, idem) This would be that the functions realized by different physical systems are the same. For Putnam machine state functionalism means that a mind = a Turing machine (finite state digital computer) + a set of instructions (a machine table or program) its operation: 1
If the machine is in state S i, and receives input I j, it will go into state S k and produce output O l (for a finite number of states, inputs and outputs). (Levine 2004) Essentially for functionalism is that the program (software) can be run on different sorts of computer hardware Multiple Realizations. (2) Psycho-Functionalist Theories Against behaviorism, cognitive psychologists consider that the behavior is the result of mental states and processes. (Fodor 1968 in Levine 2004) On a theory of this sort, what makes some neural process an instance of memory trace decay is a matter of how it functions, or the role it plays, in a cognitive system; its neural or chemical properties are relevant only insofar as they enable that process to do what trace decay is hypothesized to do. And similarly for all mental states and processes invoked by cognitive psychological theories. (Levine 2004) (3) Analytic Functionalism Analytic functionalism topic-neutral translations, or analyses, of our ordinary mental state terms or concepts. There are causal relations between a mental state and stimulations, behavior, and other mental states. (Levine 2004) Psycho-Physical Identity Theory- (Smart, 1962; Place, 1956) pain = C-fiber stimulation- not have the same meaning, they can denote the same state. According to Levine- an objection Max Black (reported in Smart, 1962): terms with different meanings can denote the same state only expressing different properties or modes of presentation of that state. If terms like pain, thought and desire are not equivalent in meaning to any physicalistic descriptions, they can denote physical states only by expressing irreducibly mental properties of them. Thus, even if pain and Cfiber stimulation pick out a single type of neural state, this state must have two types of properties, 2
physical and mental, by means of which the identification can be made. This argument has come to be known as the Distinct Property Argument against materialistic theory of mind. Intentional States According to Levine, the intentional states such as beliefs, thoughts, and desires (sometimes called propositional attitudes ) in functional terms (versus Searle 1992, G. Strawson 1994, intentional states have qualitative character). Externalism : mental states represented with the help of certain features of the environments in which those individuals are embedded. (Levine 20040 Thus, if one individual's environment differs from another's, they may count as having different intentional states, even though they reason in the same ways, and have exactly the same take on those environments from their own points of view. (Levine 2004) Externalism- Putnam s Twin Earth (1975): Twin Earth- a (hypothetical) planet on which things look, taste, smell and feel exactly the way they do on Earth, but which have different underlying microscopic structures; for example, the stuff that fills the streams and comes out of the faucets, though it looks and tastes like water, has molecular structure XYZ rather than H 2 O. (Levine 2004) Our term water - different meaning for us than for our Twin Earth counterparts. The beliefs regarding natural kinds are different. Conclusion: Without the individual s environment, functionalism no representational content of intentional states. (Levine 2004) Functionalism and Qualia Functionalism no qualia or what it's like (Nagel, 1975) to have them. (Levine 20040 3
Inverted and Absent Qualia The inverted qualia objection- Ned Block (1980b; see also Block and Fodor, 1972): An individual who satisfies the functional definition of our experience of red, but is experiencing green instead. (Levine 2004) The absent qualia objection: creatures functionally equivalent to normal humans whose mental states have no qualitative character at all. (Levine 2004) The Chinese nation thought-experiment- Block (1980b): The population of China to duplicate the functional organization of a brain- receiving the equivalent of sensory input from an artificial body and passing messages back and forth via satellite. Block - such a homunculi-headed system would not have mental states with any qualitative character (other than the qualia possessed by the individuals themselves), and thus that states functionally equivalent to sensations or perceptions may lack their characteristic feels. In response- (Dennett, 1978; Levin, 1985; Van Gulick, 1989): are such creatures possible? The counterexamples = only crude examples of functional definitions. (Levine 2004) Functionalism, Zombies, and the Explanatory Gap The inverted and absent qualia objections - as challenges exclusively to functionalist theories, both conceptual and empirical, and not generally to physicalistic theories of experiential states; the main concern was that the purely relational resources of functional description were incapable of capturing the intrinsic qualitative character of states such as feeling pain, or seeing red. (Indeed, in Block's 1980, p.291, he suggests that qualitative states may best be construed as composite state[s] whose components are a quale and a [functional state], and adds, in an endnote (note 22) that the quale might be identified with a physico-chemical state.) (Levine 2004) These objections - the conceivability argument against physicalism- Kripke (1972) and Chalmers (1996) from Descartes - the Sixth Meditation - the relation between epistemology and ontology: clear and distinct mental and sensorial perceptions the existence of the mind and body. Chalmers's version of the argument (1996)- the Zombie Argument : 4
- The first premise: it is conceivable that there are molecule-for-molecule duplicates of oneself with no qualia (call them zombies, following Chalmers, 1996). - The second premise: zombies are possible, and functionalism or, more broadly, physicalism is false. (Levine 2004) Joseph Levine (1983, 1993): the explanatory gap between physical and mental states. Functionalism s reply: zombies are not really conceivable or can not be conceptual analyses of qualitative concepts (such as what it's like to see red or what it's like to feel pain) in purely functional terms + the conceivability of zombies neither implies that such creatures are possible nor opens up an explanatory gap. (Levine 2004) The Knowledge Argument Thomas Nagel (1974) and Frank Jackson (1982): a person could know all the physical and functional facts about a certain type of experience and still not know what it's like to have it. (Levine 2004) Functionalism and physicalism s replies: these special first-personal concepts need not denote any irreducibly qualitative properties. (Levine 2004) Pain = C-fiber stimulation Multiple Realization: functionalism offers an account of mental states that is compatible with materialism, without limiting the class of those with minds to creatures with brains like ours. (Levine 2004) Janet Levin Levin J. Functionalism, The Stanford Encyclopedia of Philosophy (2004 Edition), Edward N. Zalta (ed.), URL = http://plato.stanford.edu/entries/functionalism/ 5