Psychological science seeks to develop comprehensive explanations of the behavior of organisms. The form they should take has long been a contentious issue within the discipline. Even behaviorists have disagreed among themselves about the approach that should prevail. In addition, the technological challenges of the laboratory have divorced psychology from its parent discipline, philosophy. The rupture has not been uneventful: The two disciplines have often distanced each other like receding galaxies. One eminent philosopher has characterized psychology as “experimental methods and conceptual confusion,” while psychologists deem much philosophical commentary about their discipline to stem from ignorance of its methods and goals.

Since John B. Watson coined the term “behaviorism,” the movement, at various points ...