These are the uses of syllogism, as a mode of verifying any given
argument. Its ulterior uses, as respects the general course of our
intellectual operations, hardly require illustration, being in fact the
acknowledged uses of general language. They amount substantially to this,
that the inductions may be made once for all: a single careful
interrogation of experience may suffice, and the result may be registered
in the form of a general proposition, which is committed to memory or to
writing, and from which afterward we have only to syllogize. The
particulars of our experiments may then be dismissed from the memory, in
which it would be impossible to retain so great a multitude of details;
while the knowledge which those details afforded for future use, and which
would otherwise be lost as soon as the observations were forgotten, or as
their record became too bulky for reference, is retained in a commodious
and immediately available shape by means of general language.
Against this advantage is to be set the countervailing inconvenience, that
inferences originally made on insufficient evidence become consecrated,
and, as it were, hardened into general maxims; and the mind cleaves to
them from habit, after it has outgrown any liability to be misled by
similar fallacious appearances if they were now for the first time
presented; but having forgotten the particulars, it does not think of
revising its own former decision. An inevitable drawback, which, however
considerable in itself, forms evidently but a small set-off against the
immense benefits of general language.
The use of the syllogism is in truth no other than the use of general
propositions in reasoning. We _can_ reason without them; in simple and
obvious cases we habitually do so; minds of great sagacity can do it in
cases not simple and obvious, provided their experience supplies them with
instances essentially similar to every combination of circumstances likely
to arise. But other minds, and the same minds where they have not the same
pre-eminent advantages of personal experience, are quite helpless without
the aid of general propositions, wherever the case presents the smallest
complication; and if we made no general propositions, few persons would
get much beyond those simple inferences which are drawn by the more
intelligent of the brutes. Though not necessary to reasoning, general
propositions are necessary to any considerable progress in reasoning. It
is, therefore, natural and indispensable to separate the process of
investigation into two parts; and obtain general formulæ for determining
what inferences may be drawn, before the occasion arises for drawing the
inferences. The work of drawing them is then that of applying the formulæ;
and the rules of syllogism are a system of securities for the correctness
of the application.