(1828-75; during the last years
of his life professor at Marburg), materialism, which is unfruitful and
untenable as a principle, a system, and a view of the world, but useful
and indispensable as a method and a maxim of investigation, must be
supplemented by formal idealism, which, rejecting all science from mere
reason limits knowledge to the sensuous, to that which can be experienced,
yet at the same time conceives the formal element in the sense world as the
product of the organization of man, and hence makes objects conform to our
representations. Above the sensuous world of experience and of mechanical
becoming, however, the speculative impulse to construction, rounding off
the fragmentary truth of the sciences into a unified picture of the whole
truth, rears the ideal world of that which ought to be. Notwithstanding
their indefeasible certitude, the Ideas possess no scientific truth, though
they have a moral value which makes them more than mere fabrics of the
brain: man is framed not merely for the knowledge of truth, but also for
the realization of values. But since the significance of the Ideas is
only practical, and since determinations of value are not grounds
of explanation, science and metaphysics or "concept poetry"
(_Begriffsdichtung_) must be kept strictly separate.

[Footnote 1: F.A. Lange: _Logical Studies_, 1877. Cf. M. Heinze in the
_Vierteljahrsschrift fuer wissenschaftliche Philosophic_, 1877, and
Vaihinger in the work cited above, p. 610 note.]

Friedrich Paulsen of Berlin (born in 1846; cf. pp. 330, 332, note) sees in
the Kantian philosophy the foundation for the philosophy of the future. A
profounder Wolff (the self-dominion of the reason), a Prussian Hume (the
categories of the understanding are not world-categories; rejection of
anthropomorphic metaphysics), and a German Rousseau (the primacy of the
will, consideration of the demands of the heart; the good will alone, not
deeds nor culture, constitutes the worth of man; freedom, the rights of
man) in one person, Kant has withdrawn from scientific discussion the
question concerning the dependence of reality on values or the good,
which is theoretically insoluble but practically to be answered in the
affirmative, and given it over to faith. Kant is in so far a positivist
that he limits the mission of knowledge to the reduction of the
temporo-spatial relations of phenomena to rules, and declares the
teleological power of values to be undemonstr