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

438 MATHEMATICAL PHILOSOPHY
are currently employed in a large variety of sensesmost of them so vague as to be fit only for the use of
"literary" men, not for the serious use of scientific men.
What ought we to mean by the term "natural" in such
a discussion as we are now engaged in? The question
admits, I believe, of a brief answer that is fairly satisfactory. Everyone knows that the things encountered
by a normal human in the course of his experience differ
widely in respect of vagueness and certitude; some of
them are facts so regular, so well ascertained, so indubitable that they guide in all the affairs of practical life;
they are known facts, we say, and to disregard them
would be to perish like unprotected idiots or imbeciles;
such facts are of two kinds: facts of sense-perception, or
of this and memory, and facts of pure thought; the
former are familiar in the moving pageant of the world
-birth, growth, death, day, night, land, water, sky,
change of seasons, and so on; facts of pure thought are
not so obtrusively obvious but there are such facts; one
of them is-"If something S has the property P and
whatever has P has the property P', then S has P'."
Now, all such facts are compatible-each of them fits
in, as we say, with all the others. I take it that what we
ought to mean by natural is, therefore, this: Nature (or
the natural) consists of all and only such things as are
compatible (consistent) with the best-ascertained facts
of sense and of thought.
If that be what Korzybski means by "natural,"-and
I think it very probably is,-then I fully agree with him
that humans are thoroughly natural beings, that timebinding energy is a natural kind of energy, and that his
strenuous objection to the mythological conception of
man is, like his objection to the zoological conception,