CrimePsych

There are a number of different versions of the Computational Theory of Mind (CTM) but in its classical form it states that thinking is a computational process involving mental representations. These mental representations or symbols are all contained within their own unique language, the Language of Thought (LOT). A common catch phrase often seen accompanying the classical CTM is that ‘the mind is to the brain what the program is to the hardware’ but as easy an analogy as this is for those learning about the classical CTM it also opens the theory up to a whole world of criticisms and flaws.

The main problems that the classical CTM encounters are Searle’s Chinese Room argument, the problem of homunculus, how there seems to be syntax without any semantics, the frame problem of relevance and updating and the cost of representational atomism.

Probably one of the more famous arguments against the classical CTM is that of the Chinese Room argument conducted by John R. Searle. The overall point of this argument is that we have the syntax in place but it is lacking semantics. A computer can use rules to interpret symbols but this does not mean it understands what is going on. To put it another way, semantics is not intrinsic to syntax, just because a computer can understand a set of predefined rules or algorithms doesn’t mean it actually understands what its doing.

Another more recent argument, again by Searle, that by his own confession he should have seen ten years ago is that syntax seems to be imposed on the system by its observers. The fact that we can make a machine out of just about anything and have it perform computation means that the processes are not intrinsic to the system but are completely abstract.

This spawns the problem of homunculus in that if syntax is not intrinsic to the system, and computation is defined syntactically, then nothing can intrinsically be a digital computer based exclusively on its corporeal properties. The computational theory of mind, always in some way commits the homunculus fallacy wherein they treat the mind as a little man inside the brain, and this little man uses the brain to execute his computations. However proponents of the CTM make a reasonable attempt at eradicating such a problem by supposing recursive decomposition. This states that there are multiple levels of homunculus within any system such that at the lowest level there is a ‘stupid’ homunculus doing simple yes-no, 1-0 type computations. Regrettably though the problem still remains in that the syntax is not intrinsic to the system, and we must therefore have a homunculus that stands outside the system to provide the system with its operating syntax.

There are a number of other problems that the classical computational theory of mind encounters which we have not had enough time to examine in depth here. The cost of representational atomism, together with the frame problem of relevance and updating, but also the fact that syntax has no causal powers other than those of the implementing medium all need to be explained and overcome. But that isn’t to say that the brain isn’t a digital computer, on the contrary, some other form of the computational theory of mind might contain a better explanation of how things work.

Stay tuned tomorrow for a short paper on the Connectionist Computational Theory of Mind…