Mind: A Brief Introduction (John R. Searle) / quote 73 of 138
The computational theory of mind
The collection of ideas that I have just explained contains the tools necessary to articulate the single most influential and powerful theory of the mind in the last decades of the twentieth century. The brain is a digital computer, in all probability a Universal Turing machine. As such it carries out algorithms by implementing programs, and what we call the mind is a program or a set of such programs. To understand human cognitive capacities it is only necessary to discover the programs that human beings are actually implementing when they activate such cognitive capacities as perception, memory, etc. Because the mental level of description is a program level, we do not need to understand the details of how the brain works in order to understand human cognition. Indeed, because the level of description is at a higher level than neuronal structures, we are not forced to any type-type identity theory of the mind. Rather, mental states are multiply realizable in different sorts of physical structures, which just happen to be implemented in brains but could equally well have been implemented in an indefinite range of computer hardwares. Any hardware implementation will do for the human mind provided only that it is stable enough and rich enough to carry the programs.