Induction, as above defined, is a process of inference; it proceeds from
the known to the unknown; and any operation involving no inference, any
process in which what seems the conclusion is no wider than the premises
from which it is drawn, does not fall within the meaning of the term. Yet
in the common books of Logic we find this laid down as the most perfect,
indeed the only quite perfect, form of induction. In those books, every
process which sets out from a less general and terminates in a more
general expression—which admits of being stated in the form, “This and
that A are B, therefore every A is B”—is called an induction, whether any
thing be really concluded or not: and the induction is asserted not to be
perfect, unless every single individual of the class A is included in the
antecedent, or premise: that is, unless what we affirm of the class has
already been ascertained to be true of every individual in it, so that the
nominal conclusion is not really a conclusion, but a mere re-assertion of
the premises. If we were to say, All the planets shine by the sun’s light,
from observation of each separate planet, or All the Apostles were Jews,
because this is true of Peter, Paul, John, and every other apostle—these,
and such as these, would, in the phraseology in question, be called
perfect, and the only perfect, Inductions. This, however, is a totally
different kind of induction from ours; it is not an inference from facts
known to facts unknown, but a mere short-hand registration of facts known.
The two simulated arguments which we have quoted, are not generalizations;
the propositions purporting to be conclusions from them, are not really
general propositions. A general proposition is one in which the predicate
is affirmed or denied of an unlimited number of individuals; namely, all,
whether few or many, existing or capable of existing, which possess the
properties connoted by the subject of the proposition. “All men are
mortal” does not mean all now living, but all men past, present, and to
come. When the signification of the term is limited so as to render it a
name not for any and every individual falling under a certain general
description, but only for each of a number of individuals, designated as
such, and as it were counted off individually, the proposition, though it
may be general in its language, is no general proposition, but merely that
number of singular propositions, written in an abridged character. The
operation may be very useful, as most forms of abridged notation are; but
it is no part of the investigation of truth, though often bearing an
important part in the preparation of the materials for that investigation.