Two axioms are basic to construction of unified science of psychology. The axiom of purposiveness recognizes that behavior is goal-directed. Purposiveness is evident in our evolutionary heritage of sensory-motor systems—survival tools to approach and to avoid goals. The axiom of multiple determination recognizes that perception, thought, and action result from multiple influences, including changing motivations of the organism and a variable environment.
Each axiom corresponds to a capability of organisms. The first corresponds to capability for evaluating multiple aspects of the environment in relation to operative motivations. The second corresponds to capability for integrating these multiple values into a unified resultant, manifest in goal-oriented behavior.
General theory must possess the two corresponding capabilities: To measure values of aspects of the environment within the functional goal currency of individual organisms; and to analyze operative rules of value integration.
Both capabilities have been developed in information integration theory (IIT). A solution to the long-controversial issue of true psychological measurement was obtained in this way—functional measurement—distinguished from other measurement theories by empirical success.
Multiple determination has been found to obey simple algebraic rules in many areas, from person cognition through developmental psychology and judgment-decision to animal behavior. These algebraic rules allow measurement of functional, goal-relevant values for the individual organism.
The main value of algebraic psychology lies in conceptual implications, beyond the algebraic structure. One conceptual implication concerns independence of valuation and integration—a key to functional analysis. With this goes the implication of meaning invariance. A third implication is the functional conception of memory, quite different from the traditional conception of reproductive memory. In addition, functional measurement provides a ladder to go beyond algebraic models to study nonalgebraic and configural integration.
IIT is a general, unified theory that has been developed through empirical applications of functional measurement theory. IIT is general in being empirically grounded across diverse areas. IIT is unified in that the same concepts and methods apply in all these areas. Although incomplete in many ways, IIT offers a self-sufficient approach to functional cognition, an approach near the level of the perception, thought, and action of everyday life.