The practical material principles of determination constituting the
basis of morality may be thus classified.
_1. Subjective_
External: Education; the civil constitution. Internal: Physical feeling;
moral feeling.
_2. Objective_
Internal: Perfection. External: Will of God.
The subjective elements are all experimental, or empirical, and cannot
supply the universal principle of morality, though they are expounded in
that sense by such writers as Montaigne, Mandeville, Epicurus, and
Hutcheson.
But the objective elements, as enunciated and expounded by Wolf and the
Stoics, and by Crusius and other theological moralists, are founded on
reason, for absolute perfection as a quality of things (that is, God
Himself) can only be thought of by rational concepts.
The conception of perfection in a practical sense is the adequacy of a
thing for various ends. As a human quality (and so internal) this is
simply talent, and what completes it is skill. But supreme perfection in
substance, that is, God Himself, and therefore external (considered
practically), is the adequacy of this being for all purposes. All these
principles above classified are material, and so can never furnish the
supreme moral law. For even the Divine will can supply a motive in the
human mind because of the expectation of happiness from it.
Therefore, the formal practical principle of the pure reason insists
that the mere form of a universal legislation must constitute the
ultimate determining principle of the will. Here is the only possible
practical principle which is sufficient to furnish categorical
imperatives, that is, practical laws which make action a duty.
It follows from this analytic that pure reason can be practical. It can
determine the will independently of all merely experimental elements.
There is a remarkable contrast between the working of the pure
speculative reason and that of the pure practical reason. In the
former--as was shown in the treatise on that subject--a pure, sensible
intuition of time and space made knowledge possible, though only of
objects of the senses.
On the contrary, the moral law brings before us a fact absolutely
inexplicable from any of the data of the world of sense. And the entire
range of our theoretical use of reason indicates a pure world of
understanding, which even positively determines it, and enables us to
know something of it--namely, a law.
We must observe the distinction between the laws of a system of nature
to which the will is subject, and of a system of nature which is subject
to the will. In the former, the objects cause the ideas which determine
the will; in the latter, the objects are caused by the will. Hence,
causality of the will has its determining principle exclusively in the
faculty of pure reason, which may, therefore, also be called a pure
practical reason.
The moral law is a law of the causality through freedom, and therefore
of the possibility of a super-sensible system of nature. It determines
the will by imposing on its maxim the condition of a universal
legislative form, and thus it is able for the first time to impart
practical reality to reason, which otherwise would continue to be
transcendent when seeking to proceed speculatively with its ideas.
Thus the moral law induces a stupendous change. It changes the
transcendent use of reason into the immanent use. And in result reason
itself becomes, by its ideas, an efficient cause in the field of
experience.