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

OR SCIENTIFIC METHOD. 2/1
one material circumstance in common. And hence the
force of the method depends on the number and variety
of the instances ; the more numerous and varied they
are, the greater is the probability that A and c are
causally connected.
"
The of causes
"plurality
is also a serious obstacle to
this Method. We have seen (chap. VIII. 8) that the
plurality will probably disappear before a more searching
analysis ; but still, there is a popular sense in which it
is true, for instance, that heat, light, and motion may be
caused in different ways. But until scientific investiga
tion has reduced the various
"
"
causes to a single im
mediate cause, the Method of Single Agreement breaks
down. If heat, for instance, is produced by friction,
combustion, electricity,
all these real causes would be
eliminated by this method, for they are points in which
the different instances of heat differ.
Hence the real worth of the Method is seen when we
regard it not as a proof of a case of causation, but as a
stage in scientific inquiry. It "points to the probability
of some law of causation which, if discovered, would
explain more satisfactorily the facts disclosed to our
observation," and "paves the way for other and more
effective methods." :
Its real significance appears when
we state Mill s canon thus : When
observation shows
that two events accompany one another (either simul
taneously or in succession), it is probable that they
are causally connected ; and the probability increases
with the number and variety of the instances. The
student should notice the difference between this method
and the method of simple enumeration (i.e., counting
instances). As Mr Laurie says, in the Method of Agree-
1 H. Laurie, Methods of Inductive Inquiry y Mind, vol. ii. (1893),
PP- 3I9-338-