The solution is to remember how certain you are of any "facts", and speak and act appropriately. If I've personally dug into X and have formed a very high leve

The solution is to remember how certain you are of any "facts", and speak and act appropriately. If I've personally dug into X and have formed a very high level of certainty that X is true, then I will say "X is a fact" to my friends. If I've merely read or heard assertions of X, from a source I somewhat trust, then I will tell my friends "Bob told me X" / "I remember reading X" / "I have the impression that X" / etc. The vast majority of facts (e.g. did George Washington have a set of wooden teeth, or ivory teeth, or what?) are irrelevant to any decisions I or my friends might make. I will be fine leaving my level of certainty in the "I think I vaguely remember reading X" category indefinitely. If X is a crucial fact impinging on some important decision that I have some part in, then I will prefer to raise my certainty about X to the "X is a fact" level, or at least to "several trustworthy sources have told me X". If, for some reason, this is impractical and I have to make a decision right now, then I guess I'll make the decision from the information I have (which may well be a cautious decision based on a 25% chance X is wrong), and I'll probably feel uncomfortable about it.