This article discusses aspects of man's instinctual aggressiveness from a psychoanalytic perspective, focusing on development of the superego and concluding that a main function of law is to help remedy man's inability to control his aggression sufficiently to allow the peaceful progression of civilized society. The two primary purposes of American criminal law are to exact retribution and to deter further criminal activity. Psychoanalytic discoveries about the relationship among the id, superego, and ego, and their association with the oral, phallic, and anal stages of infancy, lead to the conclusion that rehabilitation can occur when the superego of criminals is strengthened, thereby blocking the emergence of their antisocial id impulses. Nonetheless, the author argues that restructuring the superego is a complex, time-consuming task that cannot be readily accomplished in the chaos and violence of the prison environment. 58 notes