 At the center of Hook’s support for pragmatism was the justification of the pragmatic theory of knowledge. This justification characteristically took the form of setting the pragmatic theory against two opposing conceptions of truth which were identified as the “correspondence” theory of truth, which was advocated by philosophical Realists, and the “coherence” theory of truth, which was advanced by philosophical Idealists. For Hook, the superiority of pragmatism was most evident in the recognition that it was the only theory of knowledge which explained why the attainment of knowledge was important for human activity in its interaction with the environment. In the pragmatic theory of knowledge, the discovery and confirmation of true hypotheses about the nature of the world was understood as the realization of an instrument that enabled human beings to predict and control aspects of their environment.