But is it not also true that many prejudices are harmful, cruel, stupid, and vicious? Certainly it is. But I repeat, it does not follow that because some prejudices are harmful, we can do without prejudices altogether. All virtues carried to excess turn into vice, and become manifestations of spiritual pride; so it is with prejudices, even the best ones, and so it is with open-mindedness. I make no call never to examine our prejudices; such a call would be ridiculous. We need both the confidence to think logically about our inherited beliefs, and the humility to recognize that the world did not begin with us, nor will it end with us, and that the accumulated wisdom of mankind is likely to be greater than anything we can achieve by our unaided efforts. The expectation, desire, and pretense that we can go naked into the world, shorn of all prejudices and preconceptions, so that every situation is wholly new to us, is in equal measure foolish, dangerous, and wicked.

The pretense is harmful because we shall then deceive not only others, but ourselves, and disregard the still small voice within us. Shrillness and aggression will result. The more we insist in public upon things that we know, or even suspect, not to be true, the more intransigent and vehement we will grow. The more we reject prejudice qua prejudice, the harder it will be for us to retreat from the positions we have taken up in order to prove that we are not prejudiced. An ideological dogmatism will result, and we all know the havoc such dogmatism can wreak.

It takes judgment to know when prejudice should be maintained and when abandoned. Prejudices are like friendships: they should be kept in good repair. Friends sometimes grow apart, and so sometimes should men from their prejudices; but friendship often grows deeper with age and experience, and so should some prejudices. They are what give men character and hold them together. We cannot do without them.

(Theodore Dalrymple, In Praise of Prejudice: The Necessity of Preconceived Ideas [New York: Encounter Books, 2007], 125-6 [first published in 2006])

Note from KBJ: I'm done mining this book for quotations. It's a good book. You should acquire and read it.