Otto Liebmann (cf. also the chapter on “The Metamorphoses of the A Priori” in his Analysis of Reality) sees the fundamental truth of criticism in the irrefutable proof that, space, time, and the categories are functions of the intellect, and that subject and object are necessary correlates, inseparable factors of the empirical world, and finds Kant’s fundamental error, which the Epigones have not corrected, but made still worse, in the non-concept of the thing in itself, which must be expelled from the Kantian philosophy as a remnant of dogmatism, as a drop of alien blood, and as an illegitimate invader which has debased it.

According to Friedrich Albert Lange[1] (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