But, in fact, the distribution of these permanent
causes, with the reason for the proportions in which they coexist, has
not been reduced to a law; and this is why the sequences or coexistences
among the effects of several of them together cannot rank as laws of
nature, though they are invariable while the causes coexist. For this
same reason (since the proximate causes are traceable ultimately to
permanent causes) there are no original and independent uniformities of
coexistence between effects of different (proximate) causes, though
there may be such between different effects of the same cause.

Some, and particularly Reid, have regarded man's voluntary agency as
the true type of causation and the exclusive source of the idea. The
facts of inanimate nature, they argue, exhibit only antecedence and
sequence, while in volition (and this would distinguish it from physical
causes) we are conscious, prior to experience, of power to produce
effects: volition, therefore, whether of men or of God, must be, they
contend, an efficient cause, and the only one, of all phenomena. But, in
fact, they bring no positive evidence to show that we could have known,
apart from experience, that the effect, e.g. the motion of the limbs,
would follow from the volition, or that a volition is more than a
physical cause. In lieu of positive evidence, they appeal to the
supposed conceivableness of the direct action of will on matter, and
inconceivableness of the direct action of matter on matter. But there is
no inherent law, to this effect, of the conceptive faculty: it is only
because our voluntary acts are, from the first, the most direct and
familiar to us of all cases of causation, that men, as is seen from the
structure of languages (e.g. their active and passive voices, and
impersonations of inanimate objects), get the _habit_ of borrowing them
to explain other phenomena by a sort of original Fetichism. Even Reid
allows that there is a tendency to assume volition where it does not
exist, and that the belief in it has its sphere gradually limited, in
proportion as fixed laws of succession among external objects are
discovered.

This proneness to require the appearance of some necessary and natural
connection between the cause and its effect, i.e. some reason _per se_
why the one should produce the other, has infected most theories of
causation. But the selection of the particular agency which is to make
the connection between the physica