Logic | Page 9

belief, it depends upon
evidence; whereas, in Psychology belief is shown to depend upon
causes which may have evidentiary value or may not; for Psychology
explains quite impartially the growth of scientific insight and the
growth of prejudice.
(c) Mill, Bain, and Venn are the chief Materialist logicians; and to
guard against the error of confounding Materialism in Logic with the
ontological doctrine that nothing exists but Matter, it may suffice to
remember that in Metaphysics all these philosophers are Idealists.
Materialism in Logic consists in regarding propositions as affirming or
denying relations (cf. § 5) between matters-of-fact in the widest sense;
not only physical facts, but ideas, social and moral relations; it consists,
in short, in attending to the meaning of propositions. It treats the first
principles of Contradiction and Causation as true of things so far as
they are known to us, and not merely as conditions or tendencies of

thought; and it takes these principles as conditions of right thinking,
because they seem to hold good of Nature and human life.
To these differences of opinion it will be necessary to recur in the next
chapter (§ 4); but here I may observe that it is easy to exaggerate their
importance in Logic. There is really little at issue between schools of
logicians as such, and as far as their doctrines run parallel; it is on the
metaphysical grounds of their study, or as to its scope and
comprehension, that they find a battle-field. The present work generally
proceeds upon the third, or Materialist doctrine. If Deduction and
Induction are regarded as mutually dependent parts of one science,
uniting the discipline of consistent discourse with the method of
investigating laws of physical phenomena, the Materialist doctrine, that
the principles of Logic are founded on fact, seems to be the most
natural way of thinking. But if the unity of Deduction and Induction is
not disputed by the other schools, the Materialist may regard them as
allies exhibiting in their own way the same body of truths. The
Nominalist may certainly claim that his doctrine is indispensable:
consistently cogent forms of statement are necessary both to the
Conceptualist and to the Materialist; neither the relations of thought nor
those of fact can be arrested or presented without the aid of language or
some equivalent system of signs. The Conceptualist may urge that the
Nominalist's forms of statement and argument exist for the sake of their
meaning, namely, judgments and reasonings; and that the Materialist's
laws of Nature are only judgments founded upon our conceptions of
Nature; that the truth of observations and experiments depends upon
our powers of perception; that perception is inseparable from
understanding, and that a system of Induction may be constructed upon
the axiom of Causation, regarded as a principle of Reason, just as well
as by considering it as a law of Nature, and upon much the same lines.
The Materialist, admitting all this, may say that a judgment is only the
proximate meaning of a proposition, and that the ultimate meaning, the
meaning of the judgment itself, is always some matter-of-fact; that the
other schools have not hitherto been eager to recognise the unity of
Deduction and Induction or to investigate the conditions of trustworthy
experiments and observations within the limits of human understanding;
that thought is itself a sort of fact, as complex in its structure, as

profound in its relations, as subtle in its changes as any other fact, and
therefore at least as hard to know; that to turn away from the full reality
of thought in perception, and to confine Logic to artificially limited
concepts, is to abandon the effort to push method to the utmost and to
get as near truth as possible; and that as to Causation being a principle
of Reason rather than of Nature, the distinction escapes his
apprehension, since Nature seems to be that to which our private minds
turn upon questions of Causation for correction and instruction; so that
if he does not call Nature the Universal Reason, it is because he loves
severity of style.
CHAPTER II
GENERAL ANALYSIS OF PROPOSITIONS
§ 1. Since Logic discusses the proof or disproof, or (briefly) the testing
of propositions, we must begin by explaining their nature. A
proposition, then, may first be described in the language of grammar as
a sentence indicative; and it is usually expressed in the present tense.
It is true that other kinds of sentences, optative, imperative,
interrogative, exclamatory, if they express or imply an assertion, are not
beyond the view of Logic; but before treating such sentences, Logic,
for greater precision, reduces them to their equivalent sentences
indicative. Thus, I wish it were summer may be understood to mean,
The coming of summer is an object of my desire. Thou shalt not