I. DEFINITION.
Practical principles are propositions which contain a general
determination of the will, having under it several practical rules.
They are subjective, or maxims, when the condition is regarded by
the subject as valid only for his own will, but are objective, or
practical laws, when the condition is recognized as objective, that
is, valid for the will of every rational being.
REMARK.
Supposing that pure reason contains in itself a practical motive,
that is, one adequate to determine the will, then there are
practical laws; otherwise all practical principles will be mere
maxims. In case the will of a rational being is pathologically
affected, there may occur a conflict of the maxims with the
practical laws recognized by itself. For example, one may make it
his maxim to let no injury pass unrevenged, and yet he may see that
this is not a practical law, but only his own maxim; that, on the
contrary, regarded as being in one and the same maxim a rule for the
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 communication 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 completely 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.
