Argument is useless when there is either no conviction at all or a very strong conviction. It is a means of conviction and as such belongs to the means of conviction, not to the extremes.
 Samuel Butler, The Note-Books of Samuel Butler (1912). copy citation

Context

“We are not won by argument, which is like reading and writing and disappears when there is need of such vanity, or like colour that vanishes with too much light or shade, or like sound that becomes silence in the extremes. Argument is useless when there is either no conviction at all or a very strong conviction. It is a means of conviction and as such belongs to the means of conviction, not to the extremes. We are not won by arguments that we can analyse, but by tone and temper, by the manner which is the man himself.
Logic and Philosophy
When you have got all the rules and all the lore of philosophy and logic well into your head, and have spent years in getting to understand at any rate what they mean and have them at command, you will know less for practical purposes than one who has never studied logic or philosophy.
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