ABSTRACT
Psychoanalytic theory deals with many aspects of human thought and ac tion, but above all it is a theory of motivation. Its emphasis on the basic urges and forces that underlie human psychology-on man's unconscious impulses, on sexuality and aggression-have made it the most influential theory of human motivation. Yet the conceptual underpinning of the moti vational theory-the concepts of psychic energy, of libido, of conservation or economy, of the life and death instincts-has long been its weakest as pect. In fact, the evidence from a variety of sources now makes it clear that a theory based on these concepts is no longer tenable. Those officially com mitted to it can only defend it by a series of rear-guard actions that seem increasingly ineffectual.
