26o Kant: A Biographywill never be able to carry us beyond the usual course of experience" is
most important for undermining "the foundations of abstruse philosophy,
which seems to have hitherto served only as a shelter to superstition, and
a cover to obscurity and error." It essentially fulfills thus the negative task
of limiting the sphere of metaphysics. In addition, according to Hume, the
principle also has the positive effect of liberating us from "religious fears
and prejudices" and supporting in this way a more humane moral outlook
on life, strengthening the "easy and obvious philosophy."^45 The negative
theoretical strictures are meant to contribute to a more positive moral
outlook. For Hume, the principle may even have positive religious conse¬
quences, because it shows that if there is a "true" religion, then it must be
based on faith. By limiting "the principles of human reason," this prin¬
ciple may make room for faith.
What Kant calls "Hume's principle" sums up the most fundamental tenet
of Hume's mitigated skepticism, but it also sums up the most important
outcome of Kant's first Critique. For what Kant in the Prolegomena calls
"Hume's principle" is nothing but a different formulation of what Kant
identifies in the very same context as the
proposition, which is the resume [Resultat] of the whole Critique: Reason by all a pri¬
ori principles never teaches us anything more than objects of possible experience, and
even of these nothing more than can be known in experience.^46
Kant admits here that "the resume of the whole Critique" is essentially a
negative principle. It limits our use of reason and thus also the scope of
metaphysics. When one disregards the phrases characterizing reason as hav¬
ing a priori principles, as one may do here without distorting the intent of
the sentence, Kant simply says that "reason never teaches us anything
more... than can be known in experience."
Like Hume, Kant believes that this negative theoretical principle has a
positive moral point, for it has "the inestimable benefit, that all objections
to morality and religion will be for ever silenced, and this in Socratic
fashion, namely, by the clearest proof of the ignorance of the objectors"
(Bxxxi).^47 Contrary to Hume, Kant believes that this principle is not the
last word on the issues addressed in speculative philosophy. Hume's prin¬
ciple needs a friendly amendment. Taking his point of departure from
Hume's criticisms of deism and theism, Kant finds that
Hume's objections to deism are weak, and affect only the proofs and not the deistic
assertion itself. But as regards theism, which depends on a stricter determination of
the concept of the Supreme Being, which in deism is merely transcendent, they are