Founder of a Metaphysics of Morals 307we must assume that God exists.I41 But we have a choice in this matter, that
is, it is not absolutely necessary to pass judgment on first causes. The prac¬
tical need of reason, by contrast, is absolutely necessary and not condi¬
tional. In this case, Kant claimed, we must pass judgment. "For the purely
practical use of reason consists in the formulation of moral laws," which
lead "to the idea of the highest good that is possible in the world."^142 This
highest good consists of a moral state in the world in which the greatest
happiness coincides with the strictest observation of moral rules. It has thus
two components for Kant. The first is morality in accordance with the cat¬
egorical imperative (as already discussed in the Groundwork); the second
is happiness in proportion to moral worth. But there is no necessary rela¬
tion between morality and happiness. Indeed, often it seems the case that
bad things happen primarily to good people. Nevertheless, we must believe
that eventually good deeds will make a difference in the world. Thus rea¬
son needs to assume that happiness in proportion to moral worth is pos¬
sible, even though nature itself cannot be expected to bring it about. Only
an intelligent and all-powerful moral agent can be expected to do this.
Therefore, the highest good makes it necessary for a moral agent to assume
that there is another cause that makes the highest good possible. This can
only be a supreme intelligence that has moral concerns, that is, God. There¬
fore, we must assume the existence of God. The final point is new, and it
anticipates a central argument of the Critique of Practical Reason.
Kant then went on to point out that this need of reason does not enable
us to know that God exists. It only justifies a belief. Still - and this seems
to be Kant's most important concern in the essay — this is a rational belief.
"Every belief, even of a historical kind must be ... rational (for reason is
always the ultimate touchstone of truth); but a rational belief is one which
is based on no other data than those inherent in pure reason."^143 Rational
belief is what should take the place of Mendelssohn's "healthy reason." It
is what gives us orientation in speculation. This rational belief is not just
a belief in certain articles of faith, recommended by reason; it is also a be¬
lief in reason itself. Both Jacobi and Mendelssohn seem to have lost this
belief, and both have therefore opened the door to zealotry.
Zealotry is inimical to freedom of thought, which is only possible if we
submit to reason and its laws. Trying to "emancipate" oneself from reason
amounts to throwing away freedom of thought. The "maxim of the inde¬
pendence of reason from its own need (i.e., the renunciation of rational be¬
lief) is called unbelief." This rational unbelief is undesirable and will lead
to libertinism or "the principle of no longer acknowledging any duty."^144