The Church–Turing Fallacy
Gualtiero Piccinini · 2020
Abstract The Church–Turing thesis (CT) says that, if a function is computable in the intuitive sense, then it is computable by Turing machines. CT has been employed in arguments for the Computational Theory of Cognition (CTC). One argument is that cognitive functions are Turing-computable because all physical processes are Turing-computable. A second argument is that cognitive functions are Turing-computable because cognitive processes are effective in the sense analyzed by Alan Turing. A third argument is that cognitive functions are Turing-computable because Turing-computable functions are the only type of function permitted by a mechanistic psychology. This chapter scrutinizes these arguments and argues that they are unsound. Although CT does not support CTC, it is not irrelevant to it. By eliminating misunderstandings about the relationship between CT and CTC, we deepen our appreciation of CTC as an empirical hypothesis.