mportance of the view thus presented by the
theory of Monism is, for all purposes of psychological analysis,
inestimable. It is impossible nowadays that such analysis can proceed
very far in any direction without confronting the facts presented by
physiology: hence it is impossible for such analysis to confine itself
exclusively to the spiritual or subjective side of psychology. On the
other hand, in so far as such analysis has regard to the material or
objective side, it has hitherto appeared to countenance--in however
disguised a form--the dogmatic denial of the Will as an agent. Hence the
supreme importance to psychology of reconciling the hitherto rival
theories of Spiritualism and Materialism in the higher synthesis which
is furnished by the theory of Monism. For, obviously, in the absence of
any philosophical justification of the Will as an agent, we are without
any guarantee that all psychological inquiry is not a vain beating of
the air. If, as Materialism necessarily implies, the Will is not a cause
in Nature, there would be no reason in Nature for the agency either of
feeling or of intelligence. Feeling and intelligence would, therefore,
stand as ciphers in the general constitution of things; and any inquiry
touching their internal system of causation could have no reference to
any scientific inquiry touching causation in general. I am aware that
this truth is habitually overlooked by psychologists; but it is none
the less a truth of fundamental importance to the whole superstructure
of this science. Or, in other words, unless psychologists will expressly
consent to rear their science on the basis provided by the philosophical
theory of Monism, there is nothing to save it from logical
disintegration; apart from this basis, the whole science is, so to
speak, built in the air, like an unsubstantial structure of clouds.
Psychologists, I repeat, habitually ignore this fact, and constantly
speak of feeling and intelligence as true causes of adjustive action;
but by so doing they merely beg from this contradictory theory of
Spiritualism a flat denial of the fundamental postulate on which they
elsewhere proceed--the postulate, namely, that mental changes are
determined by cerebral changes. Consider, for example, the following
passage from Mr. Spencer's _Principles of Psychology_ (Sec. 125), which
serves to show in brief compass the logical incoherency which in this
matter runs through his whole work:--

'Those r