The Book of John Stuart Mill 3 · Written by himself, from On Liberty and his Autobiography
This man wrote his own books. He is the only one in this scripture who never had a religion — not that he threw it off, but that he never had it. Chapters 2 and 3 supply what the scripture was missing: the reason The Rule 7 lets the Stoa contradict the canon.
3.1There is one prohibition, and it is the only one I mean to lay down.
3.2To know a doctrine you must know what its opponents say. Everybody can say that much.
3.3I want to go one step further, and few are willing to take it.
3.4You may not learn the other side from the mouths of your own side.
3.5It is not enough to hear your teacher say "this is what they hold" and then hear him refute it.
3.6That does not count. That is a scarecrow wearing the other man’s coat.
3.7What you must hear is the sentence as it is spoken by someone who actually believes it.
3.8By a man who holds it as his own life, doing his very utmost for it.
3.9Someone says: I can put his case more strongly myself. (cf. 2 Aristotle 1.8)
3.10That is good. It is not enough.
3.11You can supply his reasons. You cannot supply his conviction.
3.12And the hardest part of a doctrine is often not in its reasons but in the man holding it — in why he cannot do without it.
3.13That you will not think up on your own. You have to go and listen.
3.14So I say: he who knows only his own side of the case does not properly know even that.
3.15And one more, which I kept all my life in controversy:
3.16The real offence in argument is not that a thing is said harshly.
3.17It is calling the men who disagree with you bad men.
3.18And the side that does this most is the side that happens to be winning — which never notices that it is doing it at all.