An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

314
FALLACIES.
(irepl <jo$i(TTiK,wv e\e<y%a)v), usually
referred to as the
"Sophistical Refutations." As the title suggests, the
aim of his discussion is entirely practical, to enumerate
the various tricks which might be employed in contro
versy, and were employed by many of the
"
Sophists
(ch. I.
3).
A false argument, says Aristotle, may err either in the
thoughts expressed or in the signs (words) which express
them. Hence he indicates two main classes of fallacy :
(a) those which are directly due to language (fallacies
in dictione, Trapa rrjv \e%iv\ and (b) those which arise
from the thought rather than the language (fallacies
extra dictionem, eo>
he enumerates six forms :
7-779 \e%ews). Of the first class
some of them are trifling,
being indeed dependent on the peculiarities
syntax.
I. Fallacies due to language.
"
of Greek
(i) Ambiguity of word (o/jLcovv/jiia, "equivocation").
This consists in the ambiguous use of one of the three
terms of a syllogism, so that in reality there are four
terms. Its most important case is the fallacy of am
biguous middle, already referred to (ch. V. 3). An
old example is given by De Morgan :
"
Finis rei est illius perfectio,
Mors est finis vitse,
Ergo, Mors est perfectio vitae ;
where the ambiguity may be laid on perfectio or on finis.
"
Often
Some instructive examples are given by Jevons :
the ambiguity is of a subtle and difficult character, so
that different opinions may be held concerning it. Thus
we might argue :
" * He who harms another should be punished. He
"