There is another trick which, as soon as it is practicable, makes all
others unnecessary. Instead of working on your opponent's intellect by
argument, work on his will by motive; and he, and also the audience if
they have similar interests, will at once be won over to your opinion,
even though you got it out of a lunatic asylum; for, as a general
rule, half an ounce of will is more effective than a hundredweight of
insight and intelligence. This, it is true, can be done only under
peculiar circumstances. If you succeed in making your opponent feel
that his opinion, should it prove true, will be distinctly prejudicial
to his interest, he will let it drop like a hot potato, and feel that
it was very imprudent to take it up.
A clergyman, for instance, is defending some philosophical dogma; you
make him sensible of the fact that it is in immediate contradiction
with one of the fundamental doctrines of his Church, and he abandons
it.
A landed proprietor maintains that the use of machinery in
agricultural operations, as practised in England, is an excellent
institution, since an engine does the work of many men. You give him
to understand that it will not be very long before carriages are also
worked by steam, and that the value of his large stud will be greatly
depreciated; and you will see what he will say.
In such cases every man feels how thoughtless it is to sanction a law
unjust to himself--_quam temere in nosmet legem sancimus iniquam_! Nor
is it otherwise if the bystanders, but not your opponent, belong to
the same sect, guild, industry, club, etc., as yourself. Let his
thesis be never so true, as soon as you hint that it is prejudicial to
the common interests of the said society, all the bystanders will find
that your opponent's arguments, however excellent they be, are weak
and contemptible; and that yours, on the other hand, though they were
random conjecture, are correct and to the point; you will have a
chorus of loud approval on your side, and your opponent will be driven
out of the field with ignominy. Nay, the bystanders will believe, as a
rule, that they have agreed with you out of pure conviction. For what
is not to our interest mostly seems absurd to us; our intellect being
no _siccum lumen_. This trick might be called "taking the tree by its
root"; its usual name is the _argumentum ab utili_.