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_,]