I propose that paradigmatic cases of self-deception satisfy the following conditions: (a) the person who is self-deceived about not-P pretends (in the sense of makes-believe or imagines or fantasizes) that not-P is the case, often while believing that P is the case and not believing that not-P is the case; (b) the pretense that not-P largely plays the role normally played by belief in terms of (i) introspective vivacity and (ii) motivation of action in a wide range of circumstances. Understanding (...) self-deception in this way is highly natural. And it provides a non-paradoxical characterization of the phenomenon that explains both its distinctive patterns of instability and its ordinary association with irrationality. Why, then, has this diagnosis been overlooked? I suggest that the oversight is due to a failure to recognize the philosophical significance of a crucial fact about the human mind, namely, the degree to which attitudes other than belief often play a central role in our mental and practical lives, both by "influenc[ing our]... passions and imagination," and by "governing.. .our actions.". (shrink)