you must establish P of
all the parts, species, or individuals contained in M, that is, of all
possible S_s:_ you must make good that this, that and the other S is
P, and also that this, that and the other S constitute the whole of M.
You are then entitled to conclude that All M is P: you have syllogised
one Extreme with the Middle through the other Extreme. The formal
statement of these premisses and conclusion is the Inductive
Syllogism.

This, that and the other S is P, _Major_.
This, that and the other S is all M, _Minor_.
[.'.] All M is P, _Conclusion_.
This, that and the other magnet (_i.e._, magnets individually)
attract iron.
This, that and the other magnet (_i.e._, the individuals
separately admitted) are all magnets.
[.'.] All magnets attract iron.

This, that and the other S being simply convertible with All M, you
have only to make this conversion and you have a syllogism in Barbara
where this, that and the other S figures as the Middle Term.

The practical value of this tortuous expression is not obvious.
Mediaeval logicians shortened it into what was known as the Inductive
Enthymeme: "This, that and the other, therefore all," an obvious
conclusion when this, that and the other constitute all. It is
merely an evidence of the great master's intoxication with his
grand invention. It is a proof also that Aristotle really looked
at Induction from the point of view of Interrogative Dialectic.
His question was, When is a Respondent bound to admit a general
conclusion? And his answer was, When he has admitted a certain number
of particulars, and cannot deny that those particulars constitute the
whole whose predicate is in dispute. He was not concerned primarily
with the analysis of the steps of an inquirer generalising from
Nature.

[Footnote 1: [Greek: epagoge men oun esti kai ho ex epagoges
syllogismos to dia tou eterou thateron akron to meso
syllogisasthai; Oion ei ton A G meson to B, dia tou G deixai
to A to B hyparchon.] (An. Prior., ii. 23.)]

BOOK II.

INDUCTIVE LOGIC, OR THE LOGIC OF SCIENCE.

INTRODUCTION.

Perhaps the simplest way of disentangling the leading features of
the departments of Logic is to take them in relation to historical
circumstances. These features are writ large, as it were, in history.
If we recognise that all bodies of doctrine have their origin in
practical needs, we may conceive different ages