For the majority of the eminent men of every past generation held many opinions now known to be erroneous. Why is it that there is on the whole a preponderance among mankind of rational opinions and rational conduct? If there really is this preponderance—which there must be unless human affairs are, and have always been, in an almost desperate state—it is owing to a quality of the human mind, the source of everything respectable in man either as an intellectual or as a moral being, namely, that his errors are corrigible. He is capable of rectifying his mistakes, by discussion and experience. Not by experience alone. There must be discussion, to show how experience is to be interpreted. Wrong opinions and practices gradually yield to fact and argument: but facts and arguments, to produce any effect on the mind, must be brought before it.
John Stuart Mill, On Liberty
