as science, does not attempt to
answer. It would not, I conceive, answer it even if it were able to make
out that the whole mental content in the percept can be traced back to
elementary sensations and their combinations. For the fact that in the
chemistry of mind elements may combine in perfectly new forms does not
disprove that the forms thus arising, whether sentiments or
quasi-cognitions, are invalid. Much less can psychology dispute the
validity of a percept if it cannot be sure that the mind adds nothing to
sensation and its grouping; that in the genesis of the perceptive state,
with its intuition of something external and now present as object,
nothing like a form of intelligence is superimposed on the elements of
sensation, giving to the result of their coalescence the particular
unity which we find. Whether psychology as a positive science can ever
be sure of this: whether, that is to say, it can answer the question,
"How do we come by the idea of object?" without assuming some particular
philosophic or extra-scientific theory respecting the ultimate nature of
mind, is a point which I purposely leave open.

I would contend, then, that the psychologist, in tracing the genesis of
the percept out of previous mental experiences, no more settles the
question, What is the object of perception? than the physicist settles
it in referring the sense-impression (and so the percept) to a present
material agent as its condition.

The same applies to our idea of self. I may discover the concrete
experiences which supply the filling in of the idea, and yet not settle
the question, Does intelligence add anything in the construction of the
form of this idea? and still less settle the question whether there is
any real unity answering to the idea.

If this is a correct distinction, if psychology, as science, does not
determine questions of validity or objective meaning but only of
genesis, if it looks at mental states in relation only to their temporal
and causal concomitants and not to their objects, it must follow that
our preceding analysis of illusion involves no particular philosophic
theory as to the nature of intelligence, but, so far as accurate,
consists of scientific facts which all philosophic theories of
intelligence must alike be prepared to accept. And I have little doubt
that each of the two great opposed doctrines, the intuitive and the
associational, would claim to be in a position to take up these facts
into