Abstract

The neobehaviorist Clark L. Hull and his disciple Kenneth Spence shared in common many views on the nature of science and the role of theories in psychology. However, a telling exchange in their correspondence of the early 1940s reveals a disagreement over the nature of intervening variables in behavior theory. Spence urged Hull to abandon his interpretations of intervening variables in terms of physiological models in favor of positivistic, purely mathematical interpretations that conflicted with Hull's mechanistic explanatory aims and ontological commitment to materialism. This dispute is set against the background of similar disputes in physics, and the origins of Hull's and Spence's divergent views on theoretical explanation are described