Archive for the ‘logic’ Category

Liar paradox in novel “Don Quixote”

14 February 2011 Leave a comment

While reading Cervantes’ novel Don Quixote [1], I came across the following version of the liar paradox. The quote is from Part II, Chapter 51, page 798.

Sir, a deep river divides a certain lord’s estate into two parts… Listen carefully, your worship, for the case is an important one and rather difficult. I must tell you, then, that over this river is a bridge, and at one end a gallows and a sort of courthouse, in which four judges sit to administer the law imposed by the owner of the river, the bridge and the estate. It runs like this: “Before anyone crosses this bridge, he must first state on oath where he is going and for what purpose. If he swears truly, he may be allowed to pass; but if he tells a lie, he shall suffer death by hanging on the gallows there displayed, without any hope of mercy.” Though they know the law and its rigorous conditions, many people cross the bridge and, as they clearly make true statements the judges let them pass freely. Now it happened that they once put a man on his oath, and he swore that he was going to die on the gallows there—and that was all. After due deliberation the judges pronounced as follows: “If we let this man pass freely he will have sworn a false oath and, according to the law, he must die; but he swore that he was going to die on the gallows, and if we hang him that will be the truth, so by the same law he should go free.”

[1] Cervantes. Don Quixote. Penguin Books, 1950.

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