In this study we do not advance merely from the common moral judgment (which
here is very worthy of respect) to the philosophical, as this has already been done; but
we advance by natural stages from popular philosophy (which goes no farther than it
can grope by means of examples) to metaphysics (which is not held back by anything
empirical and which, as it must measure out the entire scope of rational knowledge of
this kind, reaches even Ideas, where examples fail us). In order to make this advance,
we must follow and clearly present the practical faculty of reason from its universal
rules of determination to the point where the concept of duty arises from it.
Everything in nature works according to laws. Only a rational being has the capac-
ity of acting according to the conceptionof laws (i.e., according to principles). This
capacity is the will. Since reason is required for the derivation of actions from laws, will
is nothing less than practical reason. If reason infallibly determines the will, the actions
which such a being recognizes as objectively necessary are also subjectively necessary.
That is, the will is a faculty of choosing only that which reason, independently of incli-
nation, recognizes as practically necessary (i.e., as good). But if reason of itself does not
sufficiently determine the will, and if the will is subjugated to subjective conditions
(certain incentives) which do not always agree with the objective conditions—in a word,
if the will is not of itself in complete accord with reason (which is the actual case with
men), then the actions which are recognized as objectively necessary are subjectively
contingent, and the determination of such a will according to objective laws is a con-
straint. That is, the relation of objective laws to a will which is not completely good is
conceived as the determination of the will of a rational being by principles of reason to
which this will is not by its nature necessarily obedient.
The conception of an objective principle, so far as it constrains a will, is a command
(of reason), and the formula of this command is called an imperative.
All imperatives are expressed by an “ought” and thereby indicate the relation of
an objective law of reason to a will which is not in its subjective constitution necessar-
ily determined by this law. This relation is that of constraint. Imperatives say that it
would be good to do or to refrain from doing something, but they say it to a will which
does not always do something simply because the thing is presented to it as good to do.
Practical good is what determines the will by means of the conception of reason and
hence not by subjective causes but objectively, on grounds which are valid for every
rational being as such. It is distinguished from the pleasant, as that which has an influ-
ence on the will only by means of a sensation from purely subjective causes, which hold
for the senses only of this or that person and not as a principle of reason which holds for
everyone.*
A perfectly good will, therefore, would be equally subject to objective laws of the
good, but it could not be conceived as constrained by them to accord with them, because
FOUNDATIONS OF THEMETAPHYSICS OFMORALS 865
413*The dependence of the faculty of desire on sensations is called inclination, and inclination always indi-
cates a need. The dependence of a contingently determinable will on principles of reason, however, is called
interest. An interest is present only in a dependent will which is not of itself always in accord with reason; in the
divine will we cannot conceive of an interest. But even the human will can take an interest in something without
thereby acting from interest. The former means the practical interest in the action; the latter, the pathological
interest in the object of the action. The former indicates only the dependence of the will on principles of reason
in themselves, while the latter indicates dependence on the principles of reason for the purpose of inclination,
since reason gives only the practical rule by which the needs of inclination are to be aided. In the former case the
action interests me, and in the latter the object of the action (so far as it is pleasant for me) interests me. In the
First Section we have seen that, in the case of an action done from duty, no regard must be given to the interest
in the object, but merely to the action itself and its principle in reason (i.e., the law).
414