Is Your Brain a Computer?
Functionalism is, colloquially speaking, the theory that the mind is what the brain does. The most popular form of functionalism is computer functionalism, which posits that the mind is to the brain as software is to hardware. Computer functionalism proposes that thought is a kind of computation.
There are several strong reasons to believe that functionalism is not true. The most popular argument against functionalism is Searle's Chinese Room argument. The argument was published in 1980 by John Searle, who is a prominent philosopher of the mind at Berkley. It has been said, with only a bit of exaggeration, that the modern debate about philosophy of the mind mostly entails attempts to refute Searle's Chinese Room argument.
Searle's purpose in his Chinese Room argument was to deny the possibility of strong artificial intelligence-that is, to deny the possibility that a computer could think. This is a synopsis of Searle's Chinese Room argument:
Imagine that you are an English speaker and you do not speak Chinese. You've moved to China and you get a job working in a booth in a public square. The purpose of the both is to provide answers to questions that Chinese-speaking people write on small pieces of paper and pass into the booth through a slot. The answer is written on a small piece of paper and passed back to the Chinese person through a separate slot.
Inside the booth with you is a very large book. The book contains every question that can be asked and the corresponding answer -- all written only in Chinese. You understand no Chinese. You understand nothing written in the book. When the question is passed through the slot you match the Chinese characters in the question to the identical question in the book and you write the Chinese symbols corresponding to the answer and pass the answer back through the answer slot.
The Chinese person asking the question gets an answer that he understands in Chinese. You understand neither the question nor the answer because you do not understand Chinese.
Searle argues that you are carrying out a computation. The booth is analogous to a computer, you are analogous to a CPU, and the information written in Chinese is analogous the algorithm. The question and the answer written on the paper are the input and the output to the computer.
Searle points out that the computation performed by the booth and its occupant does not involve any understanding of the questions and answers provided. His point is that computation is an algorithmic process that does not entail understanding. A computer carries out a computation according to an algorithm without any understanding of the process, just as you carry out the computation in the booth without any understanding of the question or answer.
To use an analogy, computation is like syntax. Thought is like semantics. Thought is about understanding the process, not merely about mechanically carrying out the matching of an input to an output according to an algorithm.
The Chinese Room argument is a denial that computers are capable of thought, and it's a denial that computer functionalism is a valid description of the mind.
A number of arguments have been proposed in reply to Searle. The most common argument is that the understanding in the booth is contained in the book, and therefore that understanding is a part of computation.
The reply is that the book is analogous to an algorithm -- software written by a human programmer. Computation does indeed entail understanding, but the understanding is that of the engineers who built the computer and who programmed it. The computer itself has no understanding. Understanding is a part of computer programming, but the computer itself understands nothing.
Searle proposes, and I agree, that the mind is not a kind of computation, computer functionalism is not an adequate theory the mind, and that strong artificial intelligence is not possible.
There are additional arguments against computer functionalism that I hope to discuss on another occasion.