ABSTRACT
We saw in the previous chapter that Peirce’s theory of categories occupies a fundamental place in the development of his thought; the claims of the normative sciences to provide objective foundations for logic and epistemology depended upon their being able to make use of a set of objectively founded ‘universal categories’. In this chapter, we shall examine the details of Peirce’s theory, tracing the development of his claims from the 1860s to after 1900 and evaluating the different arguments he uses to support them. As a first, crude approximation, a theory of categories is a set of highly abstract conceptions which function as a complete system of summa genera; any object of thought or experience belongs to one or other of the categories. Suppose I classify a bird as a sparrow. This does not involve assigning it to a summum genus, for we view the class of sparrows as a subclassification of a sequence of more inclusive kinds-passerines, birds, living creatures, etc. It has been held that the most inclusive class in this sequence, one that does not result from the subclassification of some wider class, is that of substances. Substance represents the ultimate kind to which sparrows belong. In that case, substance is a categorial concept. Philosophers have differed about what such concepts there are: Aristotle, for example, included quality, quantity, relation, location, etc., so that red fell under the category of quality, being large of quantity, and so on. If we have a set of categories, we have a system of classifications which has a place for anything we might experience or think about.
