a questioned asked on Quora; my answer:

A number of times. But here is one obvious case, in what amounts to metaethics. Maybe I am misapplying the idea. You tell me.

What modern normative philosophers call “morality” — and what older philosophers might have designated as “the rules and standards of justice” — depends, in practice, upon widespread reciprocity. That is, there are prisoner’s dilemmas throughout situations of conflict and potential coöperation, and it makes sense for any individual to coöperate often only if others also approach such arenas of interaction with an open attitude, not flight or fight, much less with a hankering to steal.

It has been shown that a tit-for-tat strategy of reciprocity — which closely tracks many traditional notions of justice — leads to the most widespread success. But how can you trust “the other guy” to treat you fairly, justly, and not as predator to prey?

It takes more courage than many, many folks naturally possess to approach a potentially dangerous situation with a reserved reciprocity standard in mind. So, how do we steal ourselves to this? Indeed, how can we open ourselves to such attitudes before we gain the practical experience with the world to be confident that such strategies do in fact work, for both self and other, and over a long haul?

A number of religious ideas have helped. They differ from society to society, and we call them myths, and all or most seem obvious fictional. Made up. But the threat of a punishing Deity encourages some to curb their bloodlust and “defector” urges. The idea that we are all “equal before God” helps, too. And as a number of evolutionary psychologists have pointed out, the mere contemplation of a supernatural (nature-transcendent) or metaphysical (normal existence-transcendent) Being or even Principle signals both to self and others a willingness to transcend narrow ego-interests. Setting the stage for civilized coöperation.

This sort of thing often gets swept up under the rubric of “signaling.” But such signaling works regardless of reality. There may or may not be a God. Or natural rights. Or the categorical imperative. But even fictional ideas can be real in their effects.

I sometimes think of the advance of civilization as aided by a series of outrageous fictions.

Seems like the Thomas Theorem to me.