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