It does not seem inappropriate to apply Darwin's concept of natural selection to our beliefs. Yet it would be wrong to infer that all those beliefs which have promoted habits of action congenial to survival are for that reason to be regarded as true. The "happy" stress-reducing lie is sometimes preferable to truth. Survival results from many natural adaptations; the bird that runs and kicks cannot fly. Natural selection allows our biologically evolved brains to be associated with thinking that is sometimes less than rational.