Often a person uses some folk proverb to explain a behavioral event even though, on an earlier occasion, this same person used a directly contradictory folk proverb to explain the same type of event. For example, most of us have heard or said, “look before you leap.” Now there’s a useful, straightforward bit of behavioral advice—except that I vaguely remember admonishing on occasion, “he who hesitates is lost.” And “absence makes the heart grow fonder” is a pretty clear prediction of an emotional reaction to environmental events. But then what about “out of sight, out of mind”? And if “haste makes waste,” why do we sometimes hear that “time waits for no man”? How could the saying “two heads are better than one” not be true? Except that “too many cooks spoil the broth.” If I think “it’s better to be safe than sorry,” why do I also believe “nothing ventured, nothing gained”? And if “opposites attract,” why do “birds of a feather flock together”? I have counseled many students to “never to put off until tomorrow what you can do today.” But I hope my last advisee has never heard me say this, because I just told him, “cross that bridge when you come to it.”

The enormous appeal of clichés like these is that, taken together as implicit “explanations” of behavior, they cannot be refuted. No matter what happens, one of these explanations will be cited to cover it. No wonder we all think we are such excellent judges of human behavior and personality. We have an explanation for anything and everything that happens. Folk wisdom is cowardly in the sense that it takes no risk that it might be refuted.

• Keith Stanovich, 'How to Think Straight About Psychology"