ABSTRACT
Thought may seem insubstantial—a trim reckoning, an airy nothing—but its metabolic and histological costs are high. Its prime organ, the brain, constitutes only 2% of body weight but accounts for 25% of the resting person’s total oxygen consumption and for an overwhelming proportion of all body cells. A system this costly is unlikely to have evolved unless it contributes substantially to the individual’s and the species’ survival. Its most plausible function would seem to be as a mediating control system that channels behavior into paths selected out by phylogenetic and ontogenetic experience as adaptive under prevailing monitored circumstances: However, even obvious correspondences between thought and action have proven so elusive to rigorous empirical demonstration that some scholars have conjectured that thought is a mere epiphenomenon, contributing little to the person’s coping. Indeed, early behaviorists expressed doubt, at least a Cartesian methodic doubt, about the very existence of thought (Boakes, 1984; Buckley, 1989). Even among the majority who grant that thought in some sense occurs, many have been led by the low obtained correlations to conclude that little systematic organization exists among a person’s thoughts.
