TOWARD UNIFIED THEORY*
Unified theory of psychological science rests on two axioms:
Axiom of purposiveness; Axiom of multiple determination.
Purposiveness reflects the evident fact that perception, thought, and action are directed toward goals. Multiple determination represents the evident fact that virtually all perception, thought, and action depend on multiple determinants. These two axioms are at once guides and cornerstones for construction of unified theory.
Instead of unification, psychology has become increasingly fragmented. The lack of unified theory has been overshadowed by the many fascinating recent developments, which have greatly extended our knowledge horizons, both in breadth and in depth. Ours is truly a golden age. But the excitement of these developments has increased the fragmentation in our field. The need for unified theory has been lost to sight.
The lack of unified theory reflects widespread nonconcern with the two axioms. The purposiveness of behavior was submerged in the era of conditioned responses, rote verbal learning, and psychophysical thresholds. The cognitive movement has expanded our conceptual horizons in many ways, but it has neglected value, emotion, belief, self, and other affective phenomena that are the heart of purposiveness. Multiple determination has been considered in particular situations, but mainly as specific context effects, seldom as general theory. This fragmented approach has had some notable successes, but it has led away from unified theory. Those who have been concerned with the two axioms have mostly failed to develop effective methods to deal with them.
Personal views are given on some controversial issues, especially on implications of the two axioms for directions in which to pursue unified theory. Detailed discussion of other views is not feasible here, but comments on other theories of psychological measurement are given in the notes to Section 21.6.3.____________________