If humans have evolved a capacity to deceive themselves so as to better deceive others, then human technologies, languages, ideas, and traditions might display cultural manifestations of deceptive and self-deceptive adaptations. Deceiving oneself may be easier if others are complicit in the deception. Collective self-deception is manifested as groupthink and deindividuation, and it is likely mediated and enabled by various cultural elements. Von Hippel & Trivers (VH&T) briefly discuss the social reinforcement of individual-level self-deception, but they do not elaborate upon the full implications of the cultural aspects of self-deception. We discuss the ways in which self-deception may be expressed collectively in religious and political contexts, and we present several possibilities for how gene-culture co-evolution has affected human deception and self-deception.

According to Dawkins's (Reference Dawkins1982) concept of the extended phenotype, genes are selected for how well they code for an organism's ability to manipulate its environment. An organism's environment includes other organisms, of both the same and different species. Therefore, organisms may be selected for how well they can manipulate other organisms, effectively using them as extended phenotypes of their own selfish genes. If humans have competed with one another over reproductively relevant resources throughout their evolutionary history, then selection pressures may have sculpted adaptations by which humans manipulate and deceive their reproductive rivals. In addition, given the human capacity for non-genetic transfer of information (i.e., culture), many cultural phenomena may display design features indicative of their use in deceiving oneself and others. Therefore, human genes may be selected for how well they code for psychological programs that use cultural information to deceive other humans. In effect, culture is part of our extended phenotype and is an integral part of the environment to which our genes have evolved.

Following this line of thought, we can investigate human culture for features that enable its use during deception of oneself and others. Organized religion and nationalism display several exemplar features. In most ancestral contexts, religious or political self-deception may have benefited individual members, but there was a risk of exploitation if some individuals accepted the benefits of membership without paying the costs of helping other members. In such instances, the institution in question could have been used as a tool by which some individuals manipulated others. If manipulators benefited by their manipulation, then manipulative traits may have proliferated throughout human populations (until the costs of manipulation outweighed the benefits). At the same time, the cultural tools that manipulators used to express their manipulative traits might have been refined and passed down the generations alongside the genetically coded, manipulative psychological programs. In this way, genes and culture depend on each other for the evolution and expression of deceptive and self-deceptive adaptations.

Various design features of religious and political institutions may be indicative of their role in deception and self-deception. As described by VH&T (sect. 5.5.2, para. 1), insecure societies display higher rates of religious belief, because belief in God may provide individuals with a sense of control over their lives. Assuming that this sense of control was advantageous for our ancestors because it enabled the manipulation of reproductive rivals, it should then be no surprise that humans are willing and able to accept as true certain fantastic doctrines and dogmas. Likewise, religion and nationalism exhibit a strength-in-numbers effect that facilitates collective self-deception. The costs of religious or political misinformation may not offset the benefits of joining and supporting such institutions. Therefore, the deception of individual members is made easier by the pervasiveness of self-deception within these institutions.

There are other features of organized religion and nationalism that portray self-deceptive qualities. The avoidance of information that threatens or could weaken a religious or political institution is ubiquitous. This is seen when totalitarian regimes limit the types of media that are available to the public, or when religious followers avoid being exposed to competing doctrines or scientific facts (i.e., evolution by natural selection). If exposed to threatening information, followers may attempt to rationalize away whatever threat they were exposed to or be skeptical of this information. In this way, patriots from one nation may doubt the veracity of a rival nation's messages and ideas by calling them propaganda. Likewise, creationists sometimes tie themselves into psychological knots in attempting to explain away the evidence for evolution (when they do not deny or ignore this evidence altogether).

Derogation of others and enhancement of oneself are also common features of nationalism and religion. Some examples of this include the American motto “one nation, under God,” or the belief that one is a member of the “chosen people” or of the “master race,” while dehumanizing members of other nations or religions. Furthermore, optimism about the future is pervasive within religious and political circles. This optimism can lead to a self-fulfilling prophecy if one is motivated to action by the promise of a political utopia or a heavenly paradise, but it also can be used to manipulate members into acting against their own interests. Likewise, such cultural modes of self-enhancement may increase one's confidence and lead to social solidarity with one's community, but they also may bring about social conflict and war.

According to VH&T, convincing oneself that a lie is true while knowing that it is false at some psychological level is the most extreme form of self-deception. Religion, in particular, may use the consequent cognitive dissonance to its advantage by pointing to this internal conflict as evidence of its veracity. The constant struggles to retain one's faith or to remain spiritual amid the onslaught of secularism seem to be essential features of modern Judaeo-Christian practices. In this way, religion may be an especially useful cultural tool by which individuals manipulate their rivals by imposing self-deception upon them.