at disheartening view of the foreign and mechanical nature of the real
world which our sciences and our industrial arts have impressed upon the
minds of so many of us; that contempt for superstition; that denial of
the supernatural, which seems to the typical modern man the beginning of
wisdom;--to what is all this view of reality due? To the results, and,
as I believe, to the really important results, of the modern study of
natural science. But what is the study of natural science? Practically
considered, viewed as one of the great moral activities of mankind, _the
study of science is a very beautiful and humane expression of a certain
exalted form of loyalty_. Science is, practically considered, the
outcome of the absolutely devoted labors of countless seekers for
natural truth. But how do we human beings get at what we call natural
truth? By observation--so men say--and by experience. But by whose
experience? By the united, by the synthesized, by the revised,
corrected, rationally criticized, above all by the common, experience of
many individuals. The possibility of science rests upon the fact that
human experience may be progressively treated so as to become more and
more an unity. The detached individual records the transit of a star,
observes a precipitate in a test tube, stains a preparation and examines
it under a microscope, collects in the field, takes notes in a
hospital--and loyally contributes his little fragment of a report to the
ideally unified and constantly growing totality called scientific human
experience. In doing this he employs his memory, and so conceives his
own personal life as an unity. But equally he aims--and herein consists
his scientific loyalty--to bring his personal experience into unity with
the whole course of human experience in so far as it bears upon his own
science. The collection of mere data is never enough. It is in the unity
of their interpretation that the achievements of science lie. This unity
is conceived in the form of scientific theories; is verified by the
comparative and critical conduct of experiments. But in all such work
how manifold are the presuppositions which we make when we attempt such
unification! Here is no place to enumerate these presuppositions. Some
of them you find discussed in the textbooks of the logic of science.
Some of them are instinctive, and almost never get discussed at all. But
it is here enough to say that we all presuppose _that human experien