Dissociative identity disorder (multiple personality) is increasingly diagnosed, often follows childhood trauma, and is characterized by rigidification of phenomena that resemble hypnosis. To interpret dissociated aspects of selfhood as autonomous entities is a useful heuristic; but when taken too literally, it leads to three kinds of anomaly: (1) legal: dissociators remain culpable for misdeeds carried out beyond apparent awareness or control; (2) clinical: legitimization sometimes leads not to relief, but to escalating cycles of regressive dependency; and (3) scientific: the form of dissociated entities varies with how they are defined, in ways that are intrinsically motivated and clinically manipulable. These anomalies yield to an evolutionary perspective that views dissociative identity disorder as an evolved strategy of adaptive deception of self and others; e.g., a beaten subordinate avoids further retribution by "pleading illness." Such a deceit best avoids detection when fully experienced; through its intensity and persistence, it becomes real at a new level. One's basic competencies remain intact, however, and are the source of the anomalies described. They can be clinically accessed and empowered, providing the key to therapeutic change when dissociative processes are problematic. Overall, despite clear impairment in subjective awareness and volition, dissociative-disordered individuals are best held fully accountable for the consequences of their actions.