This, which is an impudent trick, is played as follows: When your opponent has answered several of your questions without the answers turning out favourable to the conclusion at which you are aiming, advance the desired conclusion,—although it does not in the least follow,—as though it had been proved, and proclaim it in a tone of triumph. If your opponent is shy or stupid, and you yourself possess a great deal of impudence and a good voice, the trick may easily succeed. It is akin to the fallacy non causae ut causae.
If you have advanced a paradoxical proposition and find a difficulty in proving it, you may submit for your opponent’s acceptance or rejection some true proposition, the truth of which, however, is not quite palpable, as though you wished to draw your proof from it. Should he reject it because he suspects a trick, you can obtain your triumph by showing how absurd he is; should he accept it> you have got reason on your side for the moment, and must now look about you; or else you can employ the previous trick as well, and maintain that your paradox is proved by the proposition which he has accepted. For this an extreme degree of impudence is required; but experience shows cases of it, and there are people who practise it by instinct.
Another trick is to use arguments ad hominem, or ex concessis When your opponent makes a proposition, you must try to see whether it is not in some way—if needs be, only apparently—inconsistent with some other proposition which he has made or admitted, or with the principles of a school or sect which he has commended and approved, or with the actions of those who support the sect, or else of those who give it only an apparent and spurious support, or with his own actions or want of action. For example, should he defend suicide, you may at once exclaim, “Why don’t you hang yourself?” Should he maintain that Berlin is an unpleasant place to live in, you may say, “Why don’t you leave by the first train?” Some such claptrap is always possible.
[Footnote 1: The truth from which I draw my proof may he either (1) of an objective and universally valid character; in that case my proof is veracious, secundum veritatem; and it is such proof alone that has any genuine validity. Or (2) it may be valid only for the person to whom I wish to prove my proposition, and with whom I am disputing. He has, that is to say, either taken up some position once for all as a prejudice, or hastily admitted it in the course of the dispute; and on this I ground my proof. In that case, it is a proof valid only for this particular man, ad kominem. I compel my opponent to grant my proposition, but I fail to establish it as a truth of universal validity. My proof avails for my opponent alone, but for no one else. For example, if my opponent is a devotee of Kant’s, and I ground my proof on some utterance of that philosopher, it is a proof which in itself is only ad hominem. If he is a Mohammedan, I may prove my point by reference to a passage in the Koran, and that is sufficient for him; but here it is only a proof ad hominem,]