Functionalism
1
New concepts developed in connection with the computer in the mid 20th Century provided more elaborate ways of developing the physicalist vision than had been provided by Identity Theory.
The great new concept from the point of view of thinking about the relation between brain and mind was software - the set of instructions the machine is set to follow.
The von Neumann computer has a central processor, capable of a small number of elementarily simple operations, and then a vast bank of pigeonholes for numbers.
What the processor does is to get a number from a specified pigeonhole, do something with it (eg add one to it), and put the result back in the same or another pigeonhole.
Each basic operation in its repertoire is a matter of following a list of definite unambiguous rules.
Hardware is the machine: a central processor with its repertoire of elementary operations. 'Software' is the sequence of instructions that the machine works to.
We are to suppose that the brain is a computer, working through a sequence of instructions, the program, with which natural selection has equipped it for the purposes of reproduction and survival.
The brain has input from the environment, the input is then manipulated in some way and the result is stimulation of some kind being passed to the muscles of the body.
1. The description the neurophysiologist provides of a stretch of neurophysiological activity
2. In the context of the brain's program, what 'calculation' is being done by that neurophysiological activity
3. A description of the conscious experience which is to be thought of as identical with that activity/calculation.
Identifying a conscious experience with the 'calculation' being conducted by the program rather than with the neurophysiological activity which actually does the calculation allows one to think of the same type of conscious experience being carried by different types of hardware.