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

them ;
AND THE ARISTOTELIAN SYLLOGISM. 117
this is seen especially in the tendency to convert A
propositions simply, and to give wrong interpretations to
exclusive or exceptive propositions,
to take
"
only S are
P," for instance, as though it implied that "All S are P."
We now come to Mediate, as distinct from Immediate,
Inference. We shall begin by defining the process in
its simplest form. We must have two propositions
which are not equivalent, from which we derive a third
proposition that could not be obtained from either of
the others taken alone. The two given propositions are
the premises, the third is the conclusion. It is evident
that we do not necessarily derive a conclusion from the
combination of any pair of propositions whatever eg.,
"All
"
men are fallible and "All metals are elements."
These statements have nothing in common. But the
following combinations will yield conclusions :
Premises
All men are f fallible.
. . A11
( All kings are men.
Conclusion All kings are fallible.
are elements.
Premises j ^metals
(. Gold is a metal.
Conclusion Gold is an element.
In order that two propositions may result in a conclusion
they must have something in common ; and this means
that when expressed in logical form they must have a
common term, otherwise there is no link of connection
between them.
The typical example of mediate inference in what
for the present we must regard as its simplest form
is, therefore :
Premises ^ M is P.
j
I All S is M.
Conclusion All S is P.