 Understood summatively, we might define collective self-deception as the holding of a false belief in the face of evidence to the contrary by a group of people as a result of shared desires, emotions, or intentions (depending upon the account of self-deception) favoring that belief. Collective self-deception is distinct from other forms of collective false belief—such as might result from deception or lack of evidence—insofar as the false belief issues from the agents’ own self-deceptive mechanisms (however these are construed), not the absence of evidence to the contrary or presence of misinformation. Accordingly, the individuals constituting the group would not hold the false belief if their vision weren’t distorted by their attitudes (desire, anxiety, fear or the like) toward the belief. What distinguishes collective self-deception from solitary self-deception just is its social context, namely, that it occurs within a group that shares both the attitudes bringing about the false belief and the false belief itself. Compared to its solitary counterpart, self-deception within a collective is both easier to foster and more difficult to escape, being abetted by the self-deceptive efforts of others within the group.