Something said (I think it was economist Terry Kastens from K-State) one time that made a lot of sense to me at the time is (and this is paraphrased because it was a lot of years ago), "We have to make a decision. Even no decision is a decision by default. So we might as well make the best decision we can with the available information".

And this is what we do basically every day. So you may be right that it is folly to be sure of what we believe. But at the end of the day, we still have to make a decision based on what we believe. Unless you want to make decisions on what you do not believe.

John