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

326
FALLACIES.
what is called a Logical Fallacy. If, on the other hand,
the conclusion does follow from the premises, the fault
must lie in the premises themselves, and we then have
what is called a Material Fallacy. Sometimes, however,
the conclusion will appear to follow from the premises
until the meaning of the terms is examined, when it will
be found that the appearance is deceptive owing to some
ambiguity in the language. Such fallacies as these are,
strictly speaking, non-logical, since the meaning of words
is extraneous to the science which deals with thought.
But they are called Semi-logical. Thus we arrive at
three heads, namely (i) Formal or Purely Logical
Fallacies, (2) Semi-logical Fallacies or Fallacies of Am
biguity, (3) Material Fallacies." The second class,
fallacies of Ambiguity, consists of those which Aristotle
called fallacies
"
in the language
"
; the third class,
Material fallacies, consists of Aristotle s fallacies "out
side the language." The first class, Formal fallacies,
consists of breaches of the syllogistic rules, of which
examples have already been given (ch. V. 3). The
most important of these are (a) four terms, (b) un
distributed middle, (c)
illicit process of the major or
minor. The student will see that all Formal fallacies
are at bottom cases of four terms.
"
3. Inductive Fallacies," mistakes incident to in
ductive reasoning, are usually said to be of three main
types :
(a)
(I))
(c)
erroneous observation.
analogy.
generalisation.
We shall briefly point out the nature of these inductive
fallacies. At bottom they
generalisation.
are all cases of erroneous
(a) Observation is at bottom sense-perception.
All