The _Homonymy_.--This trick is to extend a proposition to something
which has little or nothing in common with the matter in question but
the similarity of the word; then to refute it triumphantly, and so
claim credit for having refuted the original statement.
It may be noted here that synonyms are two words for the same
conception; homonyms, two conceptions which are covered by the same
word. (See Aristotle, _Topica_, bk. i., c. 13.) "Deep," "cutting,"
"high," used at one moment of bodies at another of tones, are
homonyms; "honourable" and "honest" are synonyms.
This is a trick which may be regarded as identical with the sophism
_ex homonymia_; although, if the sophism is obvious, it will deceive
no one.
_Every light can be extinguished.
The intellect is a light.
Therefore it can be extinguished_.
Here it is at once clear that there are four terms in the syllogism,
"light" being used both in a real and in a metaphorical sense. But if
the sophism takes a subtle form, it is, of course, apt to mislead,
especially where the conceptions which are covered by the same word
are related, and inclined to be interchangeable. It is never subtle
enough to deceive, if it is used intentionally; and therefore cases of
it must be collected from actual and individual experience.
It would be a very good thing if every trick could receive some short
and obviously appropriate name, so that when a man used this or that
particular trick, he could be at once reproached for it.