Computation is a process of symbol manipulation.
It works according to a set of rules which operate using arbitrary symbols. The important part of computation is the set of rules or algorithms which manipulate these symbols. Computations work on mechanical rules which operate purely upon the shape of the symbol without having any knowledge about what they actually mean. Algorithms, the mechanical rules, are mindless processes which means that computation needs no explanation like a homunculus. This eliminates the problem that imagery theory posed.