What is it to deceive someone? And how is it possible to deceive oneself? Does self-deception require that people be taken in by a deceitful strategy that they know is deceitful? The literature is divided between those who argue that self-deception is intentional and those who argue that it is non-intentional. In this study, Annette Barnes offers a challenge to both the standard characterisation of other-deception and current characterizations of self-deception, examining the available explanations and exploring such questions as the self-deceiver’s false consciousness, bias, and the irrationality and objectionability of self-deception. She arrives at a non-intentional account of self-deception that is deeper and more complete than alternative non-intentional accounts and avoids the reduction of self-deceptive belief to wishful belief.