h is now so
far the case that the psychologist of this type pursues his way quite
independently of philosophy. It is true his research has advanced
considerably beyond his understanding of its province. But it is
generally recognized that he must examine those very _factors of
subjectivity_ which the natural scientist otherwise seeks to evade, and,
furthermore, that he must seek to _provide for them in nature_. He
treats the inner life in what Locke called "the plain historical
method," that is to say, instead of interpreting and defining its ideas,
he analyzes and reports upon its content. He would not seek to justify a
moral judgment, as would ethics, or to criticise the cogency of thought,
as would logic; but only to describe the actual state as he found it. In
order to make his data commensurable with the phenomena of nature, he
discovers or defines bodily conditions for the subjective content which
he analyzes. His fundamental principle of method is the postulate of
_psycho-physical parallelism_, according to which he assumes a _state of
brain or nervous system for every state of mind_. But in adopting a
province and a method the psychologist foregoes finality of truth after
the manner of all natural science. He deals admittedly with an aspect of
experience, and his conclusions are no more adequate to the nature of
the self than they are to the nature of outer objects. An admirable
reference to this abstract division of experience occurs in Kuelpe's
"Introduction to Philosophy":

"For the developed consciousness, as for the naive, every
experience is an unitary whole; and it is only the habit of
abstract reflection upon experience that makes the objective
and subjective worlds seem to fall apart as originally
different forms of existence. Just as a plane curve can be
represented in analytical geometry as the function of two
variables, the abscissae and the ordinates, without prejudice
to the unitary course of the curve itself, so the world of
human experience may be reduced to a subjective and an
objective factor, without prejudice to its real
coherence."[215:19]

[Sidenote: Psychology and Philosophy.]

Sect. 100. The problems of psychology, like those of theology, tend to
disappear as independent philosophical topics. The ultimate nature of
the self will continue to interest philosophers--more deeply, perhaps,
than any aspect of experience--but their conce