Abstract

On Thomas Reid's 18thC theory of psychology and ontology, our conception of primary qualities was original and our conception of secondary qualities was acquired. The conception of both was a response to sensations. In the Inquiry Reid insisted that our original conceptions were automatic and irresistible, while in the Essays he insisted that our conception of general attributes arises from a two step process of abstraction and generalization. These doctrines are rendered consistent by a distinction between particular attributes, which exist and are conceived by abstraction, and general attributes, which do not exist and are conceived by generalization guided by their utility in knowledge and communication.