Functionalism (psychology)
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Functionalism is the philosophical basis for much empirical research in psychology and cognitive science, which says that “mental states are constituted by their causal relations to one another and to sensory inputs and behavioral outputs” (Block, 1996).
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[edit] Definition
Turing (1950) was among the first to note that the human brain could be analogied to the computer, which has been designed to carry out certain functions. In particular, whilst computers are physical devices with electronic substrate that perform computations on inputs to give outputs, so brains are physical devices with neural substrate that perform computations on inputs which produce behaviours. While this may be fictional rather than fundamental it helps show that functionalism is the theoretical level between the physical implementation and behavioural output (Marr, 1982). Therefore, it is different from its predecessors of Cartesian dualism (advocating discrete mental and physical substances) and Skinnerian behaviourism and physicalism (declaring only physical substances) because it is only concerned with the effective functions of the brain, through its organization or its ‘software programs’.
[edit] Problems with Functionalism
[edit] Inverted Spectra
For illustration, a fictional situation using a generic person denoted "001" will be explained.
001 is asked to write on a red sheet. 001 had undergone surgery which inverted 001's green and red vision, so to 001 red appears green, and green appears red.
001 writes on the red sheet which appears green to 001. 001 has a twin, 002, who did not undergo the same operation as 001. 002 would perceive the red sheet as red even though 001 was perceiving green.
This is event of inverted spectra (Block and Fodor, 1972). It claims to present a prima facie argument against functionalism because 001 and 002 experience two states that are functionally commensurate but qualitatively dissimilar (Block, 1994). The notion that 001 and 002 can have two different qualia (the experience of experience) but remain functionally indifferent is used to demonstrate that functionalism is not robust enough to explain individual differences in qualia. A answer to this argument is that 001 and 002 are not actually functionally equivalent because of 001's surgery.[citation needed]
- Further information: problem of other minds
Block (1980) also argues against the functionalist proposal of multiple realizability, where hardware implementation is irrelevant because only the functional level is important. Block considers if the billion or so neurons in a brain were given functionally equivalent electronic substitutes fitted with radios to communicate and distributed to the Chinese population if China would have qualia. He thinks it could not and argues that functionalism is inadequate accordingly. Those who ascribe to functionalism argue either that the Chinese population in such a scenerio would have qualia or that qualia do not exist in the first place.[citation needed]
[edit] The Chinese Room
Often, critics see functionalism's role in consciousness as an area of weakness in the paradigm. If functionalism is correct then all thinking, including the feeling of consciousness, can be explained by computations (Penrose, 1994). The Chinese Room is a thought experiment by Searle. Simply, a person who speaks only Chinese sits inside of a room being passed notes in English to which he gives responses based on some algorithm (e.g., for x give y). On the other end of the 'system' (i.e. the output) a person is receiving conversationally appropriate English responses to their responses and yet the Chinese man (who speaks no English) understands nothing except that for x input he is to give y. This thought experiment by Searle (1980) attempts to demonstrate that functionalism could be false because in acting as the ‘program’ executing instructions the Chinese man lacks intentionality and is only concerned with syntactic procedures rather than semantic content. Searle pre-empted critics who claimed the ‘system’ as a whole understands by positing that if the Chinese man remembered all the possible instructions and went about his life he still would not understand English.
[edit] Inductive Functionalism
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This concerns the issue that accurately knowing what functions the brain is executing at any one time is difficult to know. For example, in a psychological investigation some variable, such as word length, might be manipulated to measure the effect on another variable, say, reaction time from which some inference about reading might be made. This describes the inductive scientific method, where reasoning is made from observed facts. However, if the example is continued and the investigation finds that longer words take longer to respond to there are several interpretations that can be made. One is that the word recognition is serial, letter by letter. Another is that it is parallel (letters are processed all at once) but longer words require more lexical ‘post-recognition’ processing. The details here are not important; however, what is important is that inductive functionalism is bad at accurately determining what functions are performed by the brain. This is a serious problem for functionalist cognitive science because where multiple explanations exist it may be impossible to ascribe one correctly or, worse, possible to ascribe one incorrectly.[citation needed]
[edit] Rejoinders
One of the central arguments against functionalism is that it fails to account for the qualitative aspects of minds or qualia. However, such arguments intuitively assume qualia exist independently of brain function. Some functionalists believe China would have qualia but that due to the size it is impossible to imagine China being conscious (Lycan, 1987). Indeed, it may be the case that we are constrained by our theory of mind (e.g. Baron-Cohen, Leslie and Frith, 1985) and will never be able to understand what Chinese consciousness is like. Therefore, if functionalism is true either qualia will exist across all hardware or will not exist at all but are illusory (Dennett, 1990).
[edit] References
- Baron-Cohen, S., Leslie, A., & Frith, U. (1985). Does the Autistic Child Have a "Theory of Mind"? Cognition 21, 37-46
- Block, N. & Fodor, J. [1972], “What Psychological States Are Not,” Philosophical Review, 83, 159-181
- Block, N. (1980). Introduction: What Is Functionalism? Readings in Philosophy of Psychology. Cambridge, MA: Harvard University Press.
- Block, N. (1994). Qualia. In S. Guttenplan (ed), A Companion to Philosophy of Mind. Oxford: Blackwell
- Block, N. (1996). What is Functionalism? The Encyclopaedia of Philosophy Supplement. New York: MacMillan Reference Books
- Chomsky, N. (1975). Reflections on Language. New York: Pantheon
- Dennett, D. (1990) Quining Qualia. In W. Lycan, (ed), Mind and Cognition. Oxford: Blackwells
- Harnad, S (2001) What's Wrong and Right About Searle's Chinese Room Argument? In Bishop, M. and Preston, J., (Eds.) Essays on Searle's Chinese Room Argument. Oxford University Press.
- Lycan, W. (1987) Consciousness. Cambridge, MA: MIT Press.
- Marr, D. (1982). Vision: A Computational Approach. San Francisco: Freeman & Co.
- Mundale, J. and Bechtel, W. (1996). Integrating Neuroscience, Psychology, and Evolutionary Biology through a Teleological Conception of Function. Minds and Machines, 6, 481-505.
- Penrose, R. (1994). Shadows of the Mind. Oxford: Oxford University Press.
- Searle, J.R. (1980) Minds, brains, and programs. Behavioural and Brain Sciences, 3 (3), 417-457
- Turing, A.M. (1950) Computing Machinery and Intelligence. Mind, 49, 433-460.
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