Implicit in C. I. Lewis's conceptual pragmatism is an account of how our ideas undergo a process of social development. Lewis's account of that process resolves a problem with Josiah Royce's theory of ideas. Royce holds that there are both sensuous and symbolic ideas. It is, however, possible for someone to have only a sensuous idea of how middle C sounds and for another person to have only the symbolic idea that middle C is 261.63 Hz. In what sense, if at all, can these two persons have the same idea, namely, the idea of middle C? On Lewis's account, while ideas in individual minds are typically constituted of both sensory correlates and pure concepts, ideas are also social products that individuals inherit through education and language acquisition. For two people to have the same idea is for them both to be heirs to the social development of the idea.
