chanical sciences. J.S. Mill argues
that, scientifically, the cause of anything is the total assemblage of
the conditions that precede its appearance, and that we have no right to
give the name of cause to one of them exclusively of the others. The
answer to this is that Mill fails to recognize that cause is a
conception which we find useful in our dealings with nature, and that
whatever conceptions we find useful we are justified in using. Among the
conditions of an event there are always one or two that stand in
specially close relation to it from our point of view; e.g. the draught
of alcoholic liquor is more closely related to the man's drunkenness
than is the attraction of the earth's gravity, though that also must
co-operate in producing the effect. Such closely related conditions we
find it convenient to single out by a term which expresses their analogy
to the cause of causes, human volition.

These are the questions respecting causation which are matters of
present controversy; there are in addition many other points which
belong to the controversies of the past. Among the most important are
Aristotle's classification of causes into material, formal, efficient
and final, set forth in his _Physics_ and elsewhere, and known as his
doctrine of the Four Causes; Geulincx's Occasional Causes, meant as a
solution of certain difficulties in the cosmology of Descartes;
Leibnitz's law of Sufficient Reason; and Kant's explanation of cause and
effect as an a priori category of the understanding, intended as an
answer to Hume's scepticism, but very much less effective than the line
of explanation suggested by Locke.

The following is a list of the various technical terms connected with
causation which have been distinguished by logicians and psychologists.

The four Aristotelian causes are: (1) _Material cause_ ([Greek: yle])
the material out of which a thing is made; the material cause of a house
is the bricks and mortar of which it is composed. (2) _Formal cause_
([Greek: eidos, logos, to ti en einai]), the general external
appearance, shape, form of a thing; the formal cause of a triangle is
its triangularity. (3) _Efficient cause_ ([Greek: arche tes kineseos]),
the alcohol which makes a man drunk, the pistol-bullet which kills. This
is the cause as generally understood in modern usage. (4) _Final cause_
([Greek: telos, to ou eneka]), the object for which an action is done or
a thing produced; the final cause of a comm