The present day shows with appalling clarity how little able people are to let the other man’s argument count, although this capacity is a fundamental and indispensable condition for any human community. Everyone who proposes to come to terms with himself must reckon with this basic problem. For, to the degree that he does not admit the validity of the other person, he denies the “other” within himself the right to exist – and vice versa. The capacity for inner dialogue is a touchstone for outer objectivity.
Carl G. Jung The Practice of Psychotherapy CW 16
But the peculiar evil of silencing the expression of an opinion is that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it. If the opinion is right, they are deprived of the opportunity of exchanging error for truth, if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error. It is necessary to, consider separately these two hypotheses, each of which has a distinct branch of the argument corresponding to it. We can never he sure that the opinion we are endeavouring to stifle is a false opinion; and if we were sure, stifling it would be an evil still.
First, the opinion which it is attempted to suppress by authority may possibly be true. Those who desire to suppress it, of course deny its truth; but they are not infallible. They have no authority to decide the question for all mankind, and exclude every other person from the means of judging. To refuse a hearing to an opinion, because they are sure that it is false, is to assume that their certainty is the same thing as absolute certainty. All silencing of discussion is an assumption of infallibility. Its condemnation may be allowed to rest on this common argument, not the worse for being common.
Unfortunately for the good sense of mankind, the fact of their fallibility is far from carrying the weight in their practical judgement, which is always allowed to it in theory; for while every one well knows himself to be fallible, few think it necessary to take any precautions against their own fallibility, or admit the supposition that any opinion, of which they feel very certain, may be one of the examples of the error to which they acknowledge themselves to be liable.