Judgments of the rationality of beliefs must take the costs of acquiring and possessing beliefs into consideration. In that case, certain false beliefs, especially those that are associated with the benefits of a cohesive community, can be seen to be useful for an agent and perhaps instrumentally rational to hold. A distinction should be made between excusable misbeliefs, which a rational agent should tolerate, and misbeliefs that are defensible in their own right because they confer benefits on the agent. Likely candidates for such misbeliefs are to be found in the realm of nationalism and religion, where the possession costs of true beliefs are high, and where collective beliefs in falsehoods may allow for a cohesive community. We discuss the paradoxes of reflective awareness involved in the idea of deliberately embracing falsehoods. More rigorous, fully reflective concepts of rationality would still disallow false beliefs, but such demanding versions of rationality would commit agents to pay large costs, thereby weakening the motivation for acquiring true beliefs.

信念合理性的判断必须考虑获取和拥有信念的成本。在那种情况下，某些错误的信念，特别是那些与凝聚社区的利益相关的信念，可以被视为对一个代理有用，也许在工具上是合理的。应区分之间进行情有可原misbeliefs，其合理的代理应该容忍和misbeliefs因为它们赋予了代理的好处是在自己的权利辩护。可能会在民族主义和宗教领域找到此类错误信念的候选人，在这些领域中占有的代价真实信念的接受度很高，并且对虚假事实的集体信仰可能会使社区团结起来。我们讨论了故意接受虚假想法所涉及的反思意识的悖论。更严格，更充分地反映理性的概念仍将禁止错误的信念，但是这种要求苛刻的理性版本将使代理人付出高昂的代价，从而削弱了获取真实信念的动力。