“[Suppose that] the technology of lie-detection made us all wholly transparent. If we could never deceive each other, there might be an argument that showed that, according to S [(the Self-Interest theory)], it would be rational for everyone to cause himself not to believe S.

[S] would then be self-effacing. If we believed S, but could also change our beliefs, S would remove itself from the scene. It would become a theory that no one believed. But to be self-effacing is not to be self-defeating. It is not the aim of a theory to be believed. If we personify theories, and pretend that they have aims, the aim of a theory is not to be believed, but to be true, or to be the best theory. That a theory is self-effacing does not show that it is not the best theory.”

— Derek Parfit, Reasons and Persons (1984), p. 24