will of every rational being； it must contradict itself。 In natural
philosophy the principles of what happens； e。g。； the principle of
equality of action and reaction in the munication of motion） are at
the same time laws of nature； for the use of reason there is
theoretical and determined by the nature of the object。 In practical
philosophy； i。e。； that which has to do only with the grounds of
determination of the will； the principles which a man makes for
himself are not laws by which one is inevitably bound； because
reason in practical matters has to do with the subject； namely； with
the faculty of desire； the special character of which may occasion
variety in the rule。 The practical rule is always a product of reason；
because it prescribes action as a means to the effect。 But in the case
of a being with whom reason does not of itself determine the will；
this rule is an imperative； i。e。； a rule characterized by 〃shall；〃
which expresses the objective necessitation of the action and
signifies that； if reason pletely determined the will； the action
would inevitably take place according to this rule。 Imperatives；
therefore； are objectively valid； and are quite distinct from
maxims； which are subjective principles。 The former either determine
the conditions of the causality of the rational being as an
efficient cause； i。e。； merely in reference to the effect and the means
of attaining it； or they determine the will only； whether it is
adequate to the effect or not。 The former would be hypothetical
imperatives； and contain mere precepts of skill； the latter； on the
contrary； would be categorical； and would alone be practical laws。
Thus maxims are principles； but not imperatives。 Imperatives
themselves； however； when they are conditional （i。e。； do not determine
the will simply as will； but only in respect to a desired effect； that
is； when they are hypothetical imperatives）； are practical precepts
but not laws。 Laws must be sufficient to determine the will as will；
even before I ask whether I have power sufficient for a desired
effect； or the means necessary to produce it； hence they are
categorical： otherwise they are not laws at all； because the necessity
is wanting； which； if it is to be practical； must be independent of
conditions which are pathological and are therefore only
contingently connected with the will。 Tell a man； for example； that he
must be industrious and thrifty in youth； in order that he may not
want in old age； this is a correct and important practical precept
of the will。 But it is easy to see that in this case the will is
directed to something else which it is presupposed that it desires；
and as to this desire； we must leave it to the actor himself whether
he looks forward to other resources than those of his own acquisition；
or does not expect to be old； or thinks that in case of future
necessity he will be able to make shift with little。 Reason； from
which alone can spring a rule involving necessity； does； indeed；
give necessity to this precept （else it would not be an imperative）；
but this is a necessity dependent on subjective conditions； and cannot
be supposed in the same degree in all subjects。 But that reason may
give laws it is necessary that it should only need to presuppose
itself； because rules are objectively and universally valid only
when they hold without any contingent subjective conditions； which
distinguish one rational being from another。 Now tell a man that he
should never make a deceitful promise； this is a rule which only
concerns his will； whether the purposes he may have can be attained
thereby or not； it is the volition only which is to be determined a
priori by that rule。 If now it is found that this rule is
practically right； then it is a law； because it is a categorical
imperative。 Thus； practical laws refer to the will only； without
considering what is attained by its causality； and we may disregard
this latter （as belonging to the world of sense） in order to have them
quite pure。
II。 THEOREM I。
All practical principles which presuppose an object （matter） of
the faculty of desire as the ground of determination of the will are
empirical and can furnish no practical laws。
By the matter of the faculty of desire I mean an object the
realization of which is desired。 Now； if the desire for this object
precedes the practical rule and is the condition of our making it a
principle； then I say （in the first place） this principle is in that
case wholly empirical； for then what determines the choice is the idea
of an object and that relation of this idea to the subject by which
its faculty of desire is determined to its realization。 Such a
relation to the subject is called the pleasure in the realization of
an object。 This； then； must be presupposed as a condition of the
possibility of determination of the will。 But it is impossible to know
a priori of any idea of an object whether it will be connected with
pleasure or pain； or be indifferent。 In such cases； therefore； the
determining principle of the choice must be empirical and；
therefore； also the practical material principle which presupposes
it as a condition。
In the second place； since susceptibility to a pleasure or pain
can be known only empirically and cannot hold in the same degree for
all rational beings； a principle which is based on this subjective
condition may serve indeed as a maxim for the subject which
possesses this susceptibility； but not as a law even to him （because
it is wanting in objective necessity； which must be recognized a
priori）； it follows； therefore； that such a principle can never
furnish a practical law。
III。 THEOREM II。
All material practical principles as such are of one and the same
kind and e under the general principle of self…love or private
happiness。
Pleasure arising from the idea of the idea of the existence of a
thing； in so far as it is to determine the desire of this thing； is
founded on the susceptibility of the subject； since it depends on
the presence of an object； hence it belongs to sense （feeling）； and
not to understanding； which expresses a relation of the idea to an
object according to concepts； not to the subject according to
feelings。 It is； then； practical only in so far as the faculty of
desire is determined by the sensation of agreeableness which the
subject expects from the actual existence of the object。 Now； a
rational being's consciousness of the pleasantness of life
uninterruptedly acpanying his whole existence is happiness； and the
principle which makes this the supreme ground of determination of
the will is the principle of self…love。 All material principles； then；
which place the determining ground of the will in the pleasure or pain
to be received from the existence of any object are all of the same
kind； inasmuch as they all belong to the principle of self…love or
private happiness。
COROLLARY。
All material practical rules place the determining principle of
the will in the lower desires； and if there were no purely formal laws
of the will adequate to determine it； then we could not admit any
higher desire at all。
REMARK I。
It is surprising that men； otherwise acute； can think it possible to
distinguish between higher and lower desires； according as the ideas
which are connected with the feeling of pleasure have their origin
in the senses or in the understanding； for when we inquire what are
the determining grounds of desire； and place them in some expected
pleasantness； it is of no consequence whence the idea of this pleasing
object is derived； but only how much it pleases。 Whether an idea has
its seat and source in the understanding or not； if it can only
determine the choice by presupposing a feeling of pleasure in the
subject； it follows that its capability of determining the choice
depends altogether on the nature of the inner sense； namely； that this
can be agreeably affected by it。 However dissimilar ideas of objects
may be； though they be ideas of the understanding； or even of the
reason in contrast to ideas of sense； yet the feelin