Functionalism in the philosophy of mind

Computational approach

It was to avoid the difficulties of the theory of mind-brain identity that Hilary Putnam and Jerry Fodor proposed and developed, in the 1960s and 1970s, the computational theory of mind (or “computationalism”), to a time when computing was booming. It is a form of functionalism inspired by the computer model. Unlike the eliminativist approach to the mind, which emerged at the same time, computationalism recognizes the reality of mental states, and, unlike reductionist materialism, it also recognizes their specificity. For him, the difference between the mind and the brain corresponds simply to a difference in the way of describing the same physical phenomenon, and not to a difference between two types of phenomena. This theory is inspired by the computer model: the mind can be considered by analogy with the software or all the programs of a computer. In other words, according to a famous formula, the mind is to the brain what software is to hardware.

Software is a set of programs that allow the machine to perform various tasks and perform multiple functions. Now, while it does have a physical existence, it is not itself composed of circuits or atoms in the sense that the machine that executes a program is; nor is it composed of non-physical entities. The reality of software can only be understood if one adopts a particular level of description of the operation of the machine, where formalism disregards physical entities and their causal relationships. It is indeed in terms of symbols and functions and not in terms of circuits and electrical activity that a computer program is described. There are therefore two possible types of description of the activity of a computer machine: one strictly physical (unsuitable because excessively complex), the other formal. Similarly, there are two possible types of description associated with human behavior: the physical description of internal states or processes of the brain, such as neural activity when we do something, and the description of states or processes minds in terms of symbols and functions.

Computationalism is indeed a form of materialism in the ordinary sense since a human thought is basically considered there only as the electrochemical activation of a network of neurons. But just as one can design a computer program without mentioning the electronic circuitry that runs it, one can describe human psychology without mentioning what happens in the brain, using only the ordinary vocabulary and concepts of common sense psychology. This can be translated and developed, according to Jerry Fodor, into a formal language: the “language of thought”, which has both a “syntax” and a “semantics”. In this perspective, intentional states such as beliefs or desires are seen as mental representations of a computational type, rationally linked together by their syntax, and causally linked to the world by their semantics. The semantic content of these representations derives from the way in which these representations are caused by the physical environment.

(Artistic representation of a Turing machine.)

Biological approach

Biological functionalism is a competing theory of the computational approach to mind. Defended by some renowned philosophers such as Daniel Dennett, Ruth Millikan and David Papineau, it considers mental states not as computational states but as biological functions resulting from the evolution of species. He relies in particular on the theory of evolution by natural selection to provide a causal explanation for the appearance of these functions. The principle of natural selection also allows him to answer from a functionalist perspective the question of why mental states are realized in multiple ways. This response involves the notions of survival and reproduction in the following way:

Physical states that achieve mental states (such as hunger) are selected based on their effects on the survival and reproduction of the organisms in which they are found.
However, physical states of different types can have the same beneficial effects on the survival and reproduction of given organisms within a certain environment.
Evolution by natural selection therefore allows the existence of physical states of different types realizing the same type of mental state (such as hunger).

The biological approach to functionalism posits that all mental states are “representations”, that is, internal states of a biological organism that are in a covariant relationship with certain states in the environment. It is by virtue of this covariation relationship that internal states carry information about the environment and thus constitute a mental representation, the mind being interpreted as a natural “intentional” process. The explanation of this process must moreover be formulated without appealing to intentional concepts, since the intentionality of the representations is precisely what it is a question of explaining. The main idea of this explanatory approach consists in showing how the meaning of mental representations is constituted from unintentional natural processes such as those which are carried out in purely functional biological systems (simple organisms).

To accomplish this task, philosopher and researcher Ruth Millikan set out to study intentionality in living organisms whose cognitive system is simpler than human cognition. The strategy she developed is to find a class of biological traits that can plausibly be considered intentional, and then use these examples to determine what distinguishes intentionality from other biological functions. Broadly speaking, biological functionalism assumes that a description of mental states based on their biological functions is likely to capture all that mental states are characteristic of, since they have arisen and developed over time during the evolution where they have contributed (and continue to contribute) to the survival and reproduction of organisms that were endowed with them.

(Includes texts from Wikipedia translated and adapted by Nicolae Sfetcu)