An introductory text-book of logic - Mellone, Sydney - Rare Books at ...

306
THE THEORY OF INDUCTION
examine the relevant facts with the most rigorous exact
ness, and if there is any discrepancy, the hypothesis
must be rejected or modified. It is no paradox to say
that "the first thing is to form an hypothesis; the
second, The
to be dissatisfied with it."
instances of
Kepler and Newton show that the greatest investigators
are those who are most ready
to abandon cherished
theories, the fruit of laborious research, if they cannot
be shown to harmonise with fact. What Francis Darwin
says of his father is true of the scientific genius in every
branch of inquiry.
"
It was as though he were charged
with theorising power, ready to flow into any channel
on the slightest disturbance ; so that no fact, however
small, could avoid releasing a stream of theory, and
thus the fact became magnified into importance." In
this way many untenable theories naturally occurred to
him ; but his richness of imagination was equalled by
the power of judging, and if necessary condemning, his
theories by comparing them with facts.
Summing up the conditions of a good hypothesis, we
may
state them as follows :
(1) It must be capable of being brought into accord
with received knowledge, by mutual modification, if
necessary.
(2)
It must furnish a basis for deductive inference of
consequences.
(3) The consequences so inferred must agree with
the facts of Nature.
We have already illustrated the meaning of the first
rule (see
8, last paragraph).
by saying that the hypothesis
It is sometimes expressed
must be
"
conceivable."
This is, of course, true if "conceivable" means "not
self-contradictory" (see ch. II. 12); but it is hardly
necessary to state as a special rule that the hypothesis