Since we can never know anything for sure, it is simply not worth searching for certainty; but it is well worth searching for truth; and we do this chiefly by searching for mistakes, so that we have to correct them.
I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth.
Truth is not something that can be followed; it has to be discovered. You cannot find truth through any book or through any accumulation of experience.
Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty. Once we realize that human knowledge is fallible, we realize also that we can never be completely certain that we have not made a mistake.
The truth is something that burns. It burns off dead wood. And people don't like having the dead wood burnt off, often because they're 95 percent dead wood.
Trivers, pursuing his theory of the emotions to its logical conclusion, notes that in a world of walking lie detectors the best strategy is to believe your own lies. You can’t leak your hidden intentions if you don’t think they are your intentions. According to his theory of self-deception, the conscious mind sometimes hides the truth from itself the better to hide it from others. But the truth is useful, so it should be registered somewhere in the mind, walled off from the parts that interact with other people.
Truth lives, in fact, for the most part on a credit system. Our thoughts and beliefs pass, so long as nothing challenges them, just as bank-notes pass so long as nobody refuses them.
Dixxit 
