the great French Revolution have been carefully investigated, and
still we may doubt whether they have all been discovered, or whether
their comparative importance has been rightly determined; but it would
be very unreasonable to treat those things as miraculous and
unintelligible. We read in the _Ethics_, that a properly cultivated mind
knows what degree of precision is to be expected in each science. The
greatest possible precision is always to be sought; but what is possible
depends partly on the nature of the study and partly upon the state of
scientific preparation.

(9) To treat an agent or condition remote in time as an unconditional
cause: for every moment of time gives an opportunity for new
combinations of forces and, therefore, for modifications of the effect.
Thus, although we often say that Napoleon's Russian expedition was the
cause of his downfall, yet the effect was subject to numerous further
conditions. Had the natives not burnt Moscow, had the winter been
exceptionally mild, had the Prussians and Austrians not risen against
him, the event might have been very different. It is rash to trace the
liberties of modern Europe to the battle of Marathon. Indeed, our powers
of perception are so unequal to the subtlety of nature, that even in
experimental science there is time for molecular changes to occur
between what we treat as a cause and the effect as we perceive it; and,
in such cases, the strictly unconditional cause has not been discovered.

(10) To neglect the negative conditions to which a cause is subject.
When we say that water boils at 212 deg. F., we mean "provided the pressure
be the same as that of the atmosphere at about the sea-level"; for under
a greater pressure water will not boil at that temperature, whilst under
less pressure it boils at a lower temperature. In the usual statement of
a law of causation, 'disturbing,' 'frustrating,' 'counteracting'
circumstances (that is, negative conditions) are supposed to be absent;
so that the strict statement of such a law, whether for a remote cause,
or for an immediate cause (when only positive conditions are included),
is that the agent or assemblage of conditions, _tends_ to produce such
an effect, other conditions being favourable, or in the absence of
contrary forces.

(11) It is needless to repeat what has already been said of other
fallacies that beset inductive proof; such as the neglect of a possible
plurality of causes where the effect h