ABSTRACT
The notion of unconscious inference and the suggestion that it has a part to play in perception is, the author suppose, mainly associated with the name of Helmholtz. Helmholtz thought that the deviations of perceptual experience from what is to be expected on the basis of the constancy hypothesis are to be explained not in terms of anything further in the process of stimulation of sense-organs but in terms of ‘intellectual processes’ carried out by the perceiver. The issues are about the foundations of knowledge and whether there are such foundations and if so where they are to be sought. Whatever one thinks of Helmholtz’s theory of perceptual phenomena, it is clear that he worked with a very simple dichotomy of sensation versus intellectual processes. Both intellectual processes and sensations play a role in perception, but so do other things.
