258 Public Lectures
In conclusion, I shall comment briefly on the present-day
status of the dualistic theory of perception. It is safe and
just to say that no other theory of perception has as yet
been formulated which, by its sheer adequacy, could rule out
the dualistic theory as improbable. If you deal in all fair-
ness with space, time, and causality, it almost seems that
the dualistic theory is the only one you can arrive at. Broad,
one of the most prominent and scientific of living philoso-
phers, writes that the direct theory of perception has for
all time been demonstrated false? And physicist Planck
believes that the whole structure of physical science rests on
the proposition that “the real outer world is not directly
knowable.”2 Finally, among our American epistemologists,
there is Lovejoy, whose powerful arguments for an out-and-
out dualism have as yet received no refutation.
Aside from such evidence, however, which clearly shows
that Locke is perhaps even more alive now than when, three
hundred years ago, his fingers could push pen over paper in
defense of dualism, it seems to me that a dualistic theory of
perception will not stand forever. My reason for this belief
is what I shall call its “natural” inadequacy. As long as there
are human organisms who live and think simply, there will
be the conviction that objects are directly perceived. Dick
will continue to believe that when he looks at Harry, it is
the real Harry that he sees with his eyes, and not some
ghostly substitute for Harry in Dick’s own mind. This will
in the end, by sheer persistence, give birth to a theory of
perception whieh, without ignoring the facts of physical
science, will explain how Tom, Dick, and Harry directly
perceive one another. Such a theory, should it ever arise,
will however give mankind no occasion to put up a black
1 Mind and Its Place in Nature, pp. 184—185.
2 Where Is Science Going? p. 82.