Another example is with
cognitivist theories that argue that the human brain uses "rules" to carry out operations (these rules often conceptualised as being like the
algorithms of a
computer program). For example, in his work of the 1950s, 1960s and 1970s,
Noam Chomsky argued that (in the words of one of his books) human beings use
Rules and Representations (or to be more specific, rules acting on representations) in order to cognate (more recently Chomsky has abandoned this view; cf. the
Minimalist Program).
Now, in terms of (say) chess, the players are given "rules" (i.e., the rules of chess) to follow. So: who
uses these rules? The answer is self-evident: the players of the game (of chess) use the rules: it's not the case that the rules
themselves play chess. The rules themselves are merely inert marks on paper until a
human being reads, understands and uses them. But what about the "rules" that are, allegedly, inside our head (brain)? Who reads, understands and uses them? Again, the implicit answer is, and some would argue must be, a "homunculus": a little man who reads the rules of the world and then gives orders to the body to act on them. But again we are in a situation of
infinite regress, because this implies that the homunculus utilizes cognitive processes that are also rule bound, which presupposes another homunculus inside
its head, and so on and so forth. Therefore, so the argument goes, theories of mind that imply or state explicitly that cognition is
rule bound cannot be correct unless some way is found to "ground" the regress.
This is important because it is often assumed in
cognitive science that rules and
algorithms are essentially the same: in other words, the theory that cognition is rule bound is often believed to imply that thought (
cognition) is essentially the manipulation of algorithms, and
this is one of the key assumptions of some varieties of
artificial intelligence.
Homunculus arguments are always
fallacious unless some way can be found to "ground" the regress. In
psychology and
philosophy of mind, "homunculus arguments" (or the "homunculus fallacies") are extremely useful for detecting where theories of
mind fail or are incomplete.