In the philosophy of mind, the theory that mind is a function of the brain is called “functionalism.” Some philosophers see this as a valid version of materialism. But is it really so? In order to clarify the relation between functionalism and materialism, we examine Hilary Putnam's “functionalist” papers and some critiques of functionalism, including Putnam’s own self-critique.
The representative form of functionalism is “computer functionalism,” according to which the mind-body relation is the same as the program-hardware relation. Putnam himself started with identifying human beings with the Turing-machine. Even though they are composed of different materials, different computers can carry out the same process, and that is the model of functionalism. Computer functionalism, however, reduces the role of matter to the realizer of algorithms and does not suppose that qualities are proper to a special kind of matter that is irreplaceable by any other kind of matter. This leads to a mechanistic (Cartesian) view of nature.
Critiques of functionalism also confirm it. In Searle's famous thought experiment, the “Chinese Room,” I (who do not understand Chinese) am supposed to have a Chinese conversation only based on the manual of a Chinese message-reply without understanding its meaning. This thought experiment is becoming reality by AI technologies such as ChatGPT. But in such technologies, “function” is perfectly formulated in computer algorithms. Putnam's self-critique, based on “meaning holism,” also contrasts with Cartesian mechanism, for the latter does not require holistic consideration.
On the other hand, scientific research does not offer evidence for functionalism. They suggest, rather, the possibility of a strong dependence of mental states on physical states.
Though science is materialistic and we live in the era of science, modern scientific materialism does not necessarily support classic mechanistic theory. We should appeal to another form of materialism that does not neglect the difference in kind and individuality of matter.

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