digging further into the character of this mental contribution to
knowledge, James contented himself with the suggestion that the use of
these axiomatic principles might be construed in Darwinian style as a
'variation' surviving by its fitness, thus introducing into his account
of mental process the important idea that thinking might be tested by
its vital value.

What if knowledge be neither a dull submission to dictation from without
nor an unexplained necessity of thought? What if it be a bold adventure,
an experimental sally of a Will to live, to know and to control reality?
What if its principles were frankly _risky_, and their truth had to be
_desired_ before it was tested and assured? In a word, what if first
principles were to begin with _postulates?_ Thus the way is paved from
the new psychology to a new theory of knowledge. A third alternative to
the banal dilemma of 'empiricism' or 'apriorism' suggests itself.

The old _empiricist_ view, as typified by Mill, was that the mind had
been impressed with all its principles, such as the truths of
arithmetic, the axioms of geometry, and the law of causation, by an
uncontradicted course of experience, until it generalized facts into
'laws,' and was enabled to predict a similar future with certainty. But
this theory had really been exploded in advance by Hume. Facts do not
_appear_ as causally connected, nor, if they did, would this guarantee
that they will continue to do so in the future. The continuum of
experience, we may add, is not _given_ as a series of arithmetical units
or geometrical equalities, unless we deliberately measure it out in
accordance with mathematical principles. Empiricism thus gives no real
account of the scientific rational order of the world.

But does it follow from the failure of empiricism that apriorism is