Must we know the truth?

Since we are children, we are used to think that we need to know the truth of the facts, situations and the laws of nature to have an advantageous behavior, while to follow false beliefs is always harmful or, at best, useless; examining instead how the human mind builds the famous mental map, we saw that in fact the false beliefs are a fundamental and indispensable part in our view of the world. Hypotheses and suppositions, also very imaginative, fill enormous gaps in our knowledge about the truths on the world around us; we must remember that none of us has a magic crystal ball that shows the truth that we would like to know: we can only imagine it on the basis of what we perceive with our senses; our feelings are actually the only truth we have, their interpretation and everything that follows is the result of imagination and reason, meant as the ability to verify the consistency between the sensations received and our fantasies. Most of truth is outside our reach and this emptiness is filled with our beliefs, which later will prove to be more or less close to reality.
Centuries of experimental science and millennia of philosophy have shown us that beliefs very far from the truth have proven to be very useful since led to behaviors which were however correct; in the absence of truth, we can then be satisfied with a good forgery. Between reality and a very good illusion, there is anyway a difference that makes reality always preferable, but such a discrepancy not always clearly appears, thus making in fact the two situations equivalent. Based on this view, the concept dating back to the ancient Greece of a truth never completely knowable, but to which we can get close, is still valid and widely applied by science, whose theories are seen as approximations, generally very precise, of reality.
The truth therefore, in principle, is not a value we have, but a value to be searched although it is often an unattainable goal, a valuable asset that will never be completely ours. If instead we consider the truth as an asset to protect, then owned, this almost certainly means that we are protecting a good falsehood as truth, inevitably slipping into dogmatism.
When we say that a false but effective belief is equivalent to truth and therefore it is a good surrogate of it, we are underestimating its advantages; very often a false belief is undoubtedly better than the truth because it is very often easier to understand and use.
Therefore, if we can say that the search for truth is the first value, the most important linked to knowledge, the second is the ability to invent good falseness. This ability depends, as we said, on two valuable abilities of our mind: imagination and rationality, to which correspond two equally important values to cultivate: the creativity and consistency with the evidence of facts. The creativity should be protected from the fear of new things, that can stifle it, while the consistency needs above all to be exercised with the practice because it is a difficult and challenging art. 

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IMAGINATION 

ROYAL BOX
  CHARLES SANDERS PEIRCE