The _Extension_.--This consists in carrying your opponent's
proposition beyond its natural limits; in giving it as general a
signification and as wide a sense as possible, so as to exaggerate it;
and, on the other hand, in giving your own proposition as restricted
a sense and as narrow limits as you can, because the more general a
statement becomes, the more numerous are the objections to which it is
open. The defence consists in an accurate statement of the point or
essential question at issue.
Example 1.--I asserted that the English were supreme in drama. My
opponent attempted _to_ give an instance to the contrary, and replied
that it was a well-known fact that in music, and consequently in
opera, they could do nothing at all. I repelled the attack by
reminding him that music was not included in dramatic art, which
covered tragedy and comedy alone. This he knew very well. What he had
done was to try to generalise my proposition, so that it would apply
to all theatrical representations, and, consequently, to opera and
then to music, in order to make certain of defeating me. Contrarily,
we may save our proposition by reducing it within narrower limits
than we had first intended, if our way of expressing it favours this
expedient.
Example 2.--A. declares that the Peace of 1814 gave back their
independence to all the German towns of the Hanseatic League. B. gives
an instance to the contrary by reciting the fact that Dantzig, which
received its independence from Buonaparte, lost it by that Peace. A.
saves himself thus: "I said 'all German towns,' and Dantzig was in
Poland."
This trick was mentioned by Aristotle in the _Topica_ (bk. viii., cc.
11, 12).
Example 3.--Lamarck, in his _Philosophic Zoologique_ (vol. i., p.
208), states that the polype has no feeling, because it has no nerves.
It is certain, however, that it has some sort of perception; for it
advances towards light by moving in an ingenious fashion from branch
to branch, and it seizes its prey. Hence it has been assumed that its
nervous system is spread over the whole of its body in equal measure,
as though it were blended with it; for it is obvious that the polype
possesses some faculty of perception without having any separate
organs of sense. Since this assumption refutes Lamarck's position, he
argues thus: "In that case all parts of its body must be capable of
every kind of feeling, and also of motion, of will, of thought. The
polype would have all the organs of the most perfect animal in every
point of its body; every point could see, smell, taste, hear, and so
on; nay, it could think, judge, and draw conclusions; every particle
of its body would be a perfect animal and it would stand higher than
man, as every part of it would possess all the faculties which man
possesses only in the whole of him. Further, there would be no reason
for not extending what is true of the polype to all monads, the most
imperfect of all creatures, and ultimately to the plants, which are
also alive, etc., etc." By using dialectical tricks of this kind a
writer betrays that he is secretly conscious of being in the wrong.
Because it was said that the creature's whole body is sensitive to
light, and is therefore possessed of nerves, he makes out that its
whole body is capable of thought.