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

154
MEDIATE INFERENCE
at ; a subject is referred to a class the attributes of which
are supposed to be definitely known. Thus :
He was too ambitious to be scrupulous in his choice of
means.
He was too impulsive not to have made many blunders.
Each of these sentences contains a conclusion and an
enthymematic argument in support of it. The hearer is
understood to have in his mind a definite idea of the degree
of ambition at which a man ceases to be scrupulous, or the
degree of impulsiveness that is incompatible with accuracy."
The Aristotelian Enthymeme (evdv^/jLo) is not
necessarily an elliptically expressed syllogism; it is an
argument which aims only at establishing a result as
probable, as more than possible, but not certain to
happen, so far as our premises tell us. This ex
tremely important and frequent form of reasoning will
be discussed when we come to treat of Induction.
Because Aristotle and his commentators spoke of the
enthymeme as an "incomplete syllogism," meaning a
syllogism or argument which does not furnish complete
proof, later logicians supposed that it was
"
incom
in words. What
plete," as being not fully expressed
Aristotle has to say about enthymemes belongs essen
but the modern
tially to the doctrine of reasoning;
doctrine of the enthymeme is simply a notice of the
ways in which, in ordinary speech, we move on from
one fact or statement to another without stopping to
make all the steps definite and explicit. This is why
fallacies are so often hidden; an argument is based
upon some unexpressed assumption
examination.
which will not bear
Syllogisms may be combined, in various ways, into
"chains of reasoning." A common form is that in
which the conclusion of one syllogism furnishes one of
the premises of the next :