Noctes Atticae

How Plinius Secundus, although not without learning, failed to observe and detect the fallacy in an argument of the kind that the Greeks call a)ntistre/fon.

PLINIUS SECUNDUS was considered the most learned man of his time. He left a work, entitled For Students of Oratory, which is by no manner of means to be lightly regarded. In that work he introduces much varied material that will delight the ears of the learned. He also quotes a number of arguments that he regards as cleverly and skilfully urged in the course of debates. For instance, he cites this argument from such a debate:

'A brave man shall be given the reward which he desires. A man who had done a brave deed asked for the wife of another in marriage, and received her. Then the man whose wife she had been did a brave deed. He demands the return of his wife, but is refused.' On the part of the second brave man, who demanded the return of his wife,

says Pliny,

this elegant and plausible argument was presented: ' If the law is valid, return her to me; if it is not valid, return her.'

[*](If the law was valid, the second man ought to be granted what he desired; that is, the return of his wife. If the law was not valid, the first man's desire should not have been granted, and the second man's wife should not have been taken from him. Cf. v. 10 for a similar argument.) But it escaped Pliny's notice that this bit of reasoning, which he thought very acute, was not without the fallacy which the Greeks call a)ntistre/fon, or

a convertible proposition.

And that is a deceptive fallacy, which lies concealed under a false appearance of truth; for that very argument may just as easily be turned about and used against the same man, and might, for example, be put thus by that former husband:

If the law is valid, I do not return her; if it is not valid, I do not return her.