f _perception
through ideas_, arose from this fallacy (combined with another, viz.
that a thing cannot act where it is not). Again, the conditions of a
thing are sometimes spoken of even as though they were the thing itself.
Thus, in the Novum Organon, heat (i.e. really the conditions of the
feeling of it) is called a kind of motion; and Darwin, in his Zoonomia,
after describing _idea_ as a kind of _notion of external things_,
defines it as _a motion of the fibres_. Cousin says: 'Tout ce qui est
vrai de l'effet est vrai de la cause,' though, the reverse _might_ be
true; and Coleridge affirms, as _an evident truth_, that mind and
matter, as having no common property, cannot act on each other. The same
fallacy led Leibnitz to his _pre-established harmony_, and Malebranche
to his _occasional causes_. So, Cicero argues that mental pleasures, if
arising from the bodily, could not, as they do, exceed their cause; and
Descartes, that the Efficient Cause must have all the perfections of the
effect. Conversely Descartes, too, and persons who assail, e.g. the
Principle of Population by reference to Divine benevolence (thus
implying that, because God is perfect, therefore what _they_ think
perfection must obtain in nature), assume that effects must resemble
their causes.

CHAPTER IV.

FALLACIES OF OBSERVATION.

A fallacy of Observation (the first of the three fallacies of Proof) may
be either negative or positive.

1. The former, which is called Non-observation, is a case, not of a
positive mis-estimate of evidence, or of the proper faculties (whether
the senses or reason) not having been employed, but simply of the
non-employment of any of the faculties. It arises ([Greek: a]) from
neglect of instances. Sometimes this is when there is a stronger motive
to remember the instances on the one side, and the observers have
neglected the principle of the Elimination of Chance. Hence (the mind,
as Bacon says, being more moved by affirmative than by negative
instances) the belief in predictions, e.g. about the weather, because
they occasionally turn out correct; and the credit of the proverb, that
'Fortune favours fools,' since the cases of a wise man's success through
luck are forgotten in his more numerous successes through genius. But a
preconceived opinion is the _chief_ cause why opposing instances are
overlooked. Hence originate the errors about physical facts (e.g. of
Copernicus's foes, and friends, too, about the fall