McKay & Dennett (M&D), in their fascinating and thought-provoking article, conclude that positive illusions meet the criteria for evolved misbeliefs. I propose that the case is not made for the status of positive illusions or indeed for the idea of evolved misbeliefs.

The target article suggests that positive illusions are clearly adaptive, are universal, and are not by-products of other beliefs. Each of these suggestions can be questioned. First, a closer look at the psychological literature shows the pitfalls of positive illusions – how an inability to see their own weaknesses can prevent people from reaching important goals and can endanger their health and safety (Dunning et al. Reference Dunning, Heath and Suls2004). Looking back, one can easily see how hunters who overestimated their abilities vis-à-vis predators might not have survived to reproduce; people who had overoptimistic views about food for the winter might have starved; and parents who overestimated their children's skills might have put them in jeopardy.

Second, a closer look at the literature in cultural psychology casts doubt on the universality of positive illusions. Positive illusions are found to be a feature of Western societies, which focus on individuals and their personal prowess, but these illusions are absent or considerably weaker in Eastern cultures that focus on self-criticism, self-improvement, and adjusting to others (Heine & Lehman Reference Heine and Lehman1995; Kitayama et al. Reference Kitayama, Markus, Matsumoto and Norasakkunkit1997).

Third, the authors argue that religion is not a candidate for an evolved misbelief in part because religious beliefs are by-products of other more fundamental mechanisms, such as heightened perceptions of agency. However, they do not seem to hold positive illusions to the same rigorous standard. Are not positive illusions the very embodiment of a heightened sense of one's own agency? Thus, the case that positive illusions are singular candidates for evolved misbeliefs is still open.

However, an even more fundamental suggestion in the target article is that shared, adaptive misbeliefs need to be built in. Is this so? The psychological literature is replete with evidence for innate or very early core knowledge (e.g., knowledge about objects and number; Spelke & Kinzler Reference Spelke and Kinzler2007), as well as for such things as (a) attentional biases (e.g., to human voices: Vouloumanos & Werker Reference Vouloumanos and Werker2007; to top-heavy forms like faces: Cassia et al. Reference Cassia, Turati and Simion2004; to negative affect: Vaish et al. Reference Vaish, Grossmann and Woodward2008), (b) sensitivity to contingencies and transitional probabilities (Saffran et al. Reference Saffran, Aslin and Newport1996; Watson Reference Watson, Field and Fox1985; see also, Johnson et al. Reference Johnson, Dweck and Chen2007), and (c) considerable inferential capabilities (Woodward & Needham Reference Woodward and Needham2009).

These very basic infant attributes – core knowledge, attentional biases, sensitivities to the statistical properties of input, inferential abilities – all set infants up to learn about their worlds. Now, it makes sense to build in knowledge about things like object and number that are invariant across centuries and cultures, but, after that, it makes sense to equip infants with the apparatus to learn from their input. Indeed, it may be imperative for them to remain open to different misbeliefs, since particular misbeliefs may vary greatly in their adaptiveness across situations and cultures. In this way, Western babies can develop positive illusions, but Eastern babies can develop more self-critical and cautious stances.

In my decades of research, I have been struck by one thing more than any other: the rapidity with which children and adults alike key into the rules, beliefs, and values in a new environment. In a series of studies (Kamins & Dweck Reference Kamins and Dweck1999; Mueller & Dweck Reference Mueller and Dweck1998; see also Cimpian et al. Reference Cimpian, Arce, Markman and Dweck2007), we have shown how children are affected in dramatically different ways when, after a successful performance, they are praised once for their intelligence as opposed to their effort. After praise for intelligence, they adopt a belief in fixed intelligence and act in accordance with it. For example, they choose to work on tasks that will validate their intelligence and, after a failure, will make negative inferences about their intelligence, resulting in impaired performance. After praise for effort, children adopt a belief that ability can be increased through effort and act in accordance with that belief. They choose to work on challenging tasks that will increase their ability, and after a failure, will continue to apply effort, resulting in increased performance. We have repeated this study or variants of it eight times, with the same results.

Other recent research shows how readily people can adopt prevailing beliefs, without worrying whether they are true or false (Murphy & Dweck Reference Murphy and Dweck2009). In one study, we had people read minutes from a meeting of an organization, with the idea that they would later apply to work at that organization. The minutes implied that members of the organization believed either that intelligence was fixed or that intelligence could be developed. Before people applied to the organization, however, they went to a different room with a different experimenter to engage in a completely different task. Here, they completed a self-concept questionnaire that listed personal characteristics and asked them to rate “how much each characteristic is at the core of who you are.” What happened was striking. People who had simply read about the fixed-intelligence organization said that being brilliant was more central to who they were, but those who had read about the malleable-intelligence organization said that being passionate [about learning] was more central to who they were. They had internalized the beliefs and values of the organization and this was true even when people did not like the organization they had read about!

In fact, the science of social psychology can be seen as the science of how small changes in situations can lead to large changes in beliefs and behavior (Ross & Nisbett Reference Ross and Nisbett1991). Humans are social animals. We need to feel out and respond flexibly to new situations and this includes inferring or absorbing the (mis)beliefs that go with the new situations. If anything, it is our readiness to adopt prevalent beliefs or misbeliefs that is built into us, rather than the beliefs or misbeliefs themselves.