A System of Logic: Ratiocinative and Inductive, 7th Edition, Vol. I
John Stuart Mill · en
expressive of the series of observations, of which the generalization
called the major premise is the result.
In the argument, then, which proves that Socrates is mortal, one
indispensable part of the premises will be as follows: "My father, and
my father's father, A, B, C, and an indefinite number of other persons,
were mortal;" which is only an expression in different words of the
observed fact that they have died. This is the major premise divested of
the _petitio principii_, and cut down to as much as is really known by
direct evidence.
In order to connect this proposition with the conclusion Socrates is
mortal, the additional link necessary is such a proposition as the
following: "Socrates resembles my father, and my father's father, and
the other individuals specified." This proposition we assert when we say
that Socrates is a man. By saying so we likewise assert in what respect
he resembles them, namely, in the attributes connoted by the word man.
And we conclude that he further resembles them in the attribute
mortality.
§ 7. We have thus obtained what we were seeking, an universal type of
the reasoning process. We find it resolvable in all cases into the
following elements: Certain individuals have a given attribute; an
individual or individuals resemble the former in certain other
attributes; therefore they resemble them also in the given attribute.
This type of ratiocination does not claim, like the syllogism, to be
conclusive, from the mere form of the expression; nor can it possibly be
so. That one proposition does or does not assert the very fact which was
already asserted in another, may appear from the form of the expression,
that is, from a comparison of the language; but when the two
propositions assert facts which are _bonâ fide_ different, whether the
one fact proves the other or not can never appear from the language, but
must depend on other considerations. Whether, from the attributes in
which Socrates resembles those men who have heretofore died, it is
allowable to infer that he resembles them also in being mortal, is a
question of Induction; and is to be decided by the principles or canons
which we shall hereafter recognise as tests of the correct performance
of that great mental operation.