ge whether there is anything analogous
to them in modern needs, conceive the chief things that it behoved
Questioner and Respondent in this game to know. All that a proposition
necessarily implies; all that two propositions put together imply; on
what conditions and to what extent one admission is inconsistent with
another; when one admission necessarily involves another; when two
necessarily involve a third. And to these ends it was obviously
necessary to have an exact understanding of the terms used, so as to
avoid the snares of ambiguous language.

That a Syllogistic or Logic of Consistency should emerge out of
Yes-and-No Dialectic was natural. Things in this world come when they
are wanted: inventions are made on the spur of necessity. It was above
all necessary in this kind of debate to avoid contradicting yourself:
to maintain your consistency. A clever interrogator spread out
proposition after proposition before you and invited your assent,
choosing forms of words likely to catch your prejudices and lure
you into self-contradiction. An organon, instrument, or discipline
calculated to protect you as Respondent and guide you as Questioner
by making clear what an admission led to, was urgently called for,
and when the game had been in high fashion for more than a century
Aristotle's genius devised what was wanted, meeting at the same time,
no doubt, collateral needs that had arisen from the application of
Dialectic to various kinds of subject-matter.

The thoroughness of Aristotle's system was doubtless due partly to
the searching character of the dialectic in which it had its birth.
No other mode of disputation makes such demands upon the disputant's
intellectual agility and precision, or is so well adapted to lay bare
the skeleton of an argument.

The uses of Aristotle's logical treatises remained when the fashion
that had called them forth had passed.[6] Clear and consistent
thinking, a mastery of the perplexities and ambiguities of language,
power to detect identity of meaning under difference of expression, a
ready apprehension of all that a proposition implies, all that may
be educed or deduced from it--whatever helps to these ends must be of
perpetual use. "To purge the understanding of those errors which lie
in the confusion and perplexities of an inconsequent thinking," is
a modern description of the main scope of Logic.[7] It is a good
description of the branch of Logic that keeps closest to the
Aristo