udy of Metaphysics is necessary to
every one who would comprehend the nature and functions of Logic, or the
place of his own mind and of Reason in the world.

(d) The relation of Logic to Psychology will be discussed in the next
section.

(e) As a Regulative Science, pointing out the conditions of true
inference (within its own sphere), Logic is co-ordinate with (i) Ethics,
considered as assigning the conditions of right conduct, and with (ii)
AEsthetics, considered as determining the principles of criticism and
good taste.

Sec. 6. Three principal schools of Logicians are commonly recognised:
Nominalist, Conceptualist, and Materialist, who differ as to what it is
that Logic really treats of: the Nominalists say, 'of language'; the
Conceptualists, 'of thought'; the Materialists, 'of relations of fact.'
To illustrate these positions let us take authors who, if some of them
are now neglected, have the merit of stating their contrasted views with
a distinctness that later refinements tend to obscure.

(a) Whately, a well-known Nominalist, regarded Logic as the Science and
Art of Reasoning, but at the same time as "entirely conversant about
language"; that is to say, it is the business of Logic to discover those
modes of statement which shall ensure the cogency of an argument, no
matter what may be the subject under discussion. Thus, _All fish are
cold-blooded_, .'. _some cold-blooded things are fish:_ this is a sound
inference by the mere manner of expression; and equally sound is the
inference, _All fish are warm-blooded_, .'. _some warm-blooded things are
fish_. The latter proposition may be false, but it follows; and
(according to this doctrine) Logic is only concerned with the consistent
use of words: the truth or falsity of the proposition itself is a
question for Zoology. The short-coming of extreme Nominalism lies in
speaking of language as if its meaning were unimportant. But Whately did
not intend this: he was a man of great penetration and common-sense.

(b) Hamilton, our best-known Conceptualist, defined Logic as the science
of the "formal laws of thought," and "of thought as thought," that is,
without regard to the matter thought about. Just as Whately regarded
Logic as concerned merely with cogent forms of statement, so Hamilton
treated it as concerned merely with the necessary relations of thought.
This doctrine is called Conceptualism, because the simplest element of
thought is the Concept; that is, an