he total effect
is something quite different to the separate effects, and governed by
different laws. There the great problem is to discover, not the
properties, but the cause of the new phenomenon, i.e. the particular
conjunction of agents whence it results; which could indeed never be
ascertained by specific enquiry, were it not for the peculiarity, not of
all these cases (e.g. not of mental phenomena), but of many, viz. that
the heterogeneous effects of combined causes often reproduce, i.e. are
_transformed into_ their causes (as, e.g. water into its components,
hydrogen and oxygen). The great difficulty is _not_ there to discover
the properties of the new phenomenon itself, for these can be found by
experiment like the _simple_ effects of any other cause; since, in this
class of cases the effects of the separate causes give place to a new
effect, and thereby cease to need consideration as separate effects. But
in the far larger class of cases, viz. when the total effect is the
exact sum of the separate effects of all the causes (the case of the
Composition of Causes), at no point may it be overlooked that the effect
is not simple but complex, the result of various separate causes, all of
which are always tending to produce the whole of their several natural
effects; having, it may be, their _effects_ modified, disturbed, or even
prevented by each other, but always preserving their _action_, since
laws of causation cannot have exceptions.

These complex effects must be investigated by _deducing_ the law of the
effect from the laws of the separate causes on the combination of which
it depends. No inductive method is conclusive in such cases (e.g. in
physiology, or _a fortiori_, in politics and history), whether it be the
method of simple observation, which compares instances, whether positive
or negative, to see if they agree in the presence or the absence of one
common antecedent, or the empirical method, which proceeds by directly
trying different combinations (either made or found) of causes, and
watching what is the effect. Both are inconclusive; the former, because
an effect may be due to the concurrence of many causes, and the latter,
because we can rarely know what all the coexisting causes are; and still
more rarely whether a certain portion (if not all) of the total effect
is not due to these other causes, and not to the combination of causes
which we are observing.

CHAPTER XI.

THE DEDUCTIVE METHOD