Self-deception is made unnecessarily puzzling by the assumption that it is an intrapersonal analog of ordinary interpersonal deception. In paradigmatic cases, interpersonal deception is intentional and involves some time at which the deceiver disbelieves what the deceived believes. The assumption that self-deception is intentional and that the self-deceiver believes that some proposition is true while also believing that it is false produces interesting conceptual puzzles, but it also produces a fundamentally mistaken view of the dynamics of self-deception. This target article challenges the assumption and presents an alternative view of the nature and etiology of self-deception. Drawing upon empirical studies of cognitive biases, it resolves familiar "paradoxes" about the dynamics of self-deception and the condition of being self-deceived. Conceptually sufficient conditions for self-deception are offered and putative empirical demonstrations of a kind of self-deception in which a subject believes that a proposition is true while also believing that it is false are criticized. Self-deception is neither irresolvably paradoxical nor mysterious, and it is explicable without the assistance of mental exotica. The key to understanding its dynamics is a proper appreciation of our capacity for acquiring and retaining motivationally biased beliefs.