Logic | Page 6

when he has attained to equal proficiency in the
subject. Meanwhile, the following considerations may be offered in its
favour:
Logic states, and partly explains and applies, certain abstract principles
which all other sciences take for granted; namely, the axioms above
mentioned--the principles of Contradiction, of the Syllogism and of
Causation. By exercising the student in the apprehension of these truths,
and in the application of them to particular propositions, it educates the
power of abstract thought. Every science is a model of method, a
discipline in close and consecutive thinking; and this merit Logic ought
to possess in a high degree.
For ages Logic has served as an introduction to Philosophy that is, to
Metaphysics and speculative Ethics. It is of old and honourable descent:
a man studies Logic in very good company. It is the warp upon which
nearly the whole web of ancient, mediæval and modern Philosophy is
woven. The history of thought is hardly intelligible without it.
As the science of proof, Logic gives an account of the general nature of
evidence deductive and inductive, as applied in the physical and social
sciences and in the affairs of life. The general nature of such evidence:
it would be absurd of the logician to pretend to instruct the chemist,
economist and merchant, as to the special character of the evidence
requisite in their several spheres of judgment. Still, by investigating the

general conditions of proof, he sets every man upon his guard against
the insufficiency of evidence.
One application of the science of proof deserves special mention:
namely, to that department of Rhetoric which has been the most
developed, relating to persuasion by means of oratory, leader-writing,
or pamphleteering. It is usually said that Logic is useful to convince the
judgment, not to persuade the will: but one way of persuading the will
is to convince the judgment that a certain course is advantageous; and
although this is not always the readiest way, it is the most honourable,
and leads to the most enduring results. Logic is the backbone of
Rhetoric.
It has been disputed whether Logic is a science or an art; and, in fact, it
may be considered in both ways. As a statement of general truths, of
their relations to one another, and especially to the first principles, it is
a science; but it is an art when, regarding truth as an end desired, it
points out some of the means of attaining it--namely, to proceed by a
regular method, to test every judgment by the principles of Logic, and
to distrust whatever cannot be made consistent with them. Logic does
not, in the first place, teach us to reason. We learn to reason as we learn
to walk and talk, by the natural growth of our powers with some
assistance from friends and neighbours. The way to develop one's
power of reasoning is, first, to set oneself problems and try to solve
them. Secondly, since the solving of a problem depends upon one's
ability to call to mind parallel cases, one must learn as many facts as
possible, and keep on learning all one's life; for nobody ever knew
enough. Thirdly one must check all results by the principles of Logic. It
is because of this checking, verifying, corrective function of Logic that
it is sometimes called a Regulative or Normative Science. It cannot
give any one originality or fertility of invention; but it enables us to
check our inferences, revise our conclusions, and chasten the vagaries
of ambitious speculation. It quickens our sense of bad reasoning both in
others and in ourselves. A man who reasons deliberately, manages it
better after studying Logic than he could before, if he is sincere about it
and has common sense.

§ 5. The relation of Logic to other sciences:
(a) Logic is regarded by Spencer as co-ordinate with Mathematics, both
being Abstract Sciences--that is, sciences of the relations in which
things stand to one another, whatever the particular things may be that
are so related; and this view seems to be, on the whole, just--subject,
however, to qualifications that will appear presently.
Mathematics treats of the relations of all sorts of things considered as
quantities, namely, as equal to, or greater or less than, one another.
Things may be quantitatively equal or unequal in degree, as in
comparing the temperature of bodies; or in duration; or in spatial
magnitude, as with lines, superficies, solids; or in number. And it is
assumed that the equality or inequality of things that cannot be directly
compared, may be proved indirectly on the assumption that 'things
equal to the same thing are equal,' etc.
Logic also treats of the relations of all sorts of things, but not as to their
quantity. It considers (i) that one thing may be like or