Mathematical philosophy, a study of fate and freedom; lectures for educated laymen, by Cassius J. Keyser.

TRANSFORMATION 179
unless I am mistaken, there remains a psychological problem,-an immense and difficult one,-the task of discovering the connections of the number concepts with the
data of sensation and sense-perception. Is a class, for
example, or a relation, a percept or a concept or both?
So, too, respecting time, space and matter, if the problem
of defining their elements in logical terms were solved,
there might still remain to be solved a psychological problem; or it may be that the solutions of the two problems
willbe advanced simultaneously. Duration, for example,
seems to be a datum of sense, and so, too, as William
James long ago pointed out, voluminousness, or bulk,
appears to be a datum of sense; it may be that an instant
and time itself will be logically and psychologically defined
in terms of sense-given durations; and that a point and
space itself will reach similar definition in terms of sensegiven bulks. And similarly for similar things.
You are to be congratulated on the date df your
generation when these kindred problems, or these kindred
phases of the one great problem constituted by them,
are pressing for solution; for the problem is indeed
immense, embracing, not merely the now exciting question
of " relativity," but-what is infinitely more-the nature
of the ultimate data and ultimate structure of Knowledge.
Let me, in closing, refer you to some of the works of some
of the pioneers-to Russell's Scientific Method in Philosophy,l to his Analysis of Mind, to certain parts of Whitehead's Organization of Knowledge,2 to his Concept of
Nature, and especially to his truly momentous book,
The Principles of Natural Knowledge. Regarding the last
'Reviewed by C. J. Keyser in The Bulletin of the American Mathematical Society.
'Reviewed by C. J. Keyser in Science.