st practicable degree of precision, fixed
and determined". But in this determination, not content with simply
recognising that it is with phenomena that the Experimental Methods
primarily deal, it being indeed only phenomena that can be the
subjects of experimental management and observation, he starts by
declaring that science has not to do with any causes except such as
are phenomenal--"when I speak of the cause of any phenomenon, I do not
mean a cause which is not itself a phenomenon"--and goes on to define
as the only correct meaning of cause "the sum total of conditions,"
including among them conditions which are not phenomenal, in the sense
of being directly open to observation.

When Mill protested that he had regard only to phenomenal causes, he
spoke as the partisan of a philosophical tradition. It would have been
well if he had acted upon his own remark that the proper understanding
of the scientific method of investigating cause is independent of
metaphysical analysis of what cause means. Curiously enough, this
remark is the preface to an analysis of cause which has but slight
relevance to science, and is really the continuation of a dispute
begun by Hume. This is the key to his use of the word phenomenon: it
must be interpreted with reference to this: when he spoke of causes
as phenomenal, he opposed the word to "occult" in some supposed
metaphysical sense.[2] And this irrelevant discussion, into the
vortex of which he allowed himself to be carried, obscured the fact,
elsewhere fully recognised by Mill himself, that science does attempt
to get beyond phenomena at ultimate laws which are not themselves
phenomena though they bind phenomena together. The "colligation"
of the facts, to use Whewell's phrase, is not a phenomenon, but a
noumenon.

The truth is that a very simple analysis of "cause" is sufficient for
the purposes of scientific inquiry. It is enough to make sure that
causal sequence or consequence shall not be confounded with simple
sequence. Causal sequence is simple sequence and something more, that
something more being expressed by calling it causal. What we call a
cause is not merely antecedent or prior in time to what we call its
effect: it is so related to the effect that if it or an equivalent
event had not happened the effect would not have happened. Anything
in the absence of which a phenomenon would not have come to pass as it
did come to pass is a cause in the ordinary sense. We may desc