*Project Gutenberg*. Public domain.

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*[1] 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*,]