ABSTRACT
The theory of abstraction can be traced back to Aristotle, who opposed the doctrine that there are innate ideas in favour of the view that all our knowledge is derived from particular things: thinking, he maintained. The contents of perception, not the things themselves, are the stimuli which serve as the units for abstraction. If anything, as J. W. Reeves points out, the tradition gave increasing emphasis to the view that thinking consists of the formation of concepts through the association of simple, sensory elements, the doctrine receiving its most radical formulation by John Stuart Mill. K. L. Smoke had already questioned Hull's theory that abstraction necessarily involved identical elements. The persistence of the theory can be seen in B. J. Underwood's definition of the concept: 'The crux of concept learning is the abstraction - selection - of a common feature, characteristic or property which is present in a number of stimuli which differ on other characteristics'.
