Nietzsche on Truth and Lies

"As a means for the preserving of the individual, the intellect unfolds its principle powers in dissimulation, which is the means by which weaker, less robust individuals preserve themselves — since they have been denied the chance to wage the battle for existence with horns or with the sharp teeth of beasts of prey. This art of dissimulation reaches its peak in man. Deception, flattering, lying, deluding, talking behind the back, putting up a false front, living in borrowed splendor, wearing a mask, hiding behind convention, playing a role for others and for oneself — in short, a continuous fluttering around the solitary flame of vanity — is so much the rule and the law among men that there is almost nothing which is less comprehensible than how an honest and pure drive for truth could have arisen among them. They are deeply immersed in illusions and in dream images; their eyes merely glide over the surface of things and see "forms". Their senses nowhere lead to truth; on the contrary, they are content to receive stimuli and, as it were, to engage in a groping game on the backs of things...

Insofar as the individual wants to maintain himself against other individuals, he will under natural circumstances employ the intellect mainly for dissimulation. But at the same time, from boredom and necessity, man wishes to exist socially and with the herd; therefore, he needs to make peace and strives accordingly to banish from his world at least the most flagrant bellum omnium contra omnes [War of everyone against everyone —Tr]. This peace treaty brings in its wake something which appears to be the first step toward acquiring that puzzling truth drive: to wit, that which shall count as "truth" from now on is established. That is to say, a uniformly valid and binding designation is invented for things, and this legislation of language likewise establishes the first laws of truth. For the contrast between truth and lie arises here for the first time. The liar is a person who uses the valid designations, the words, in order to make something which is unreal appear to be real. He says, for example, "I am rich", when the proper designation for his condition would be "poor". He misuses fixed conventions by means of arbitrary substitutions or even reversals of names. If he does this in a selfish and moreover harmful manner, society will cease to trust him and will thereby exclude him. What men avoid by excluding the liar is not so much being defrauded as it is being harmed by means of fraud. Thus, even at this stage, what they hate is basically not deception itself, but rather the unpleasant, hated consequences of certain sorts of deception. It is in a similarly restricted sense that man now wants nothing but truth: he desires the pleasant, life-preserving consequences of truth. He is indifferent toward pure knowledge which has no consequences; toward those truths which are possibly harmful and destructive he is even hostilely inclined...

We still do not yet know where the drive for truth comes from. For so far we have heard only of the duty which society imposes in order to exist: to be truthful means to employ the usual metaphors. Thus, to express it morally, this is the duty to lie according to a fixed convention, to lie with the herd and in a manner binding upon everyone. Now man of course forgets that this is the way things stand for him"

--- On Truth and Lies in an Extra-Moral Sense / Friedrich Nietzsche