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

32O
FALLACIES.
secundum quid e.g., every man has a right to inculcate
his own opinions ; therefore a magistrate is
justified
in using his power to enforce his own political views.
We cannot infer of his special powers as a magistrate
what is only true of his general rights as a man. 1
To the two fallacies already mentioned in this con
nection, De Morgan rightly proposes to add a third
that of arguing from one special case to another special
case, which does not resemble it in material circum
stances. The student will see that this is really iden
tical with false analogy (ch. VIII. 4).
(3) The next fallacy was called by the Latin writers
Ignoratio Elenchi, after Aristotle s e "
Xey^ou ayvoia, ig
norance of [the nature refutation." of] To refute an
adversary s assertion, we must establish the exact logical
To prove a conclusion
contradictory of it (ch. III.
7).
which is not the contradictory is ignoratio elenchi. In
modern text-books the scope of the fallacy is extended
to cover all cases of "proving the wrong point,"
cases in which, instead of the required conclusion, a
proposition which may
Mr Welton quotes a concise example from Spencer s
all
be mistaken for it is defended.
Education :
"
Throughout his after career, a boy, in nine
cases out of ten, applies his Latin and Greek to no
practical purposes." As the same writer observes, Mr
"
ignores the fact that the advocates
Spencer s argument
of a classical education do not claim that Latin and
Greek are of direct use in practical life. What they do
urge is that the study
of the classics furnishes an un
rivalled mental training ; and it is this proposition which
1 Some writers identify the fallacy a dicto simpliciter ad dictum
secundum qiiid with the fallacy of Accident, and accordingly call the
fallacy a dicto secundum quid ad dictum simpliciter the "converse
fallacy of Accident."