In every case where an object of the will has to be supposed in order that the rule may be prescribed which is to determine the will, there the rule is simply heteronomy; the imperative is conditional, namely, IF or BECAUSE one wishes for this object, one should act so and so: hence it can never command morally, that is categorically. Whether the object determines the will by means of inclination, as in the principle of private happiness, or by means of reason directed to objects of our possible volition generally, as in the principle of perfection, in either case the will never determines itself IMMEDIATELY by the conception of the action, but only by the influence which the foreseen effect of the action has on the will; I OUGHT TO DO SOMETHING, ON THIS ACCOUNT, BECAUSE I WISH FOR SOMETHING ELSE; and here there must be yet another law assumed in me as its subject, by which I necessarily will this other thing, and this law again requires an imperative to restrict this maxim. For the influence which the conception of an object within the reach of our faculties can exercise on the will of the subject in consequence of its natural properties, depends on the nature of the subject, either the sensibility (inclination and taste), or the understanding and reason, the employment of which is by the peculiar constitution of their nature attended with satisfaction. It follows that the law would be, properly speaking, given by nature, and as such, it must be known and proved by experience, and would consequently be contingent, and therefore incapable of being an apodictic practical rule, such as the moral rule must be. Not only so, but it is INEVITABLY ONLY HETERONOMY; the will does not give itself the law, but it is given by a foreign impulse by means of a particular natural constitution of the subject adapted to receive it. An absolutely good will, then, the principle of which must be a categorical imperative, will be indeterminate as regards all objects, and will contain merely the FORM OF VOLITION generally, and that as autonomy, that is to say, the capability of the maxims of every good will to make themselves a universal law, is itself the only law which the will of every rational being imposes on itself, without needing to assume any spring or interest as a foundation.
HOW SUCH A SYNTHETICAL PRACTICAL a priori PROPOSITION IS POSSIBLE and why it is necessary, is a problem whose solution does not lie within the bounds of the metaphysic of morals; and we have not here affirmed its truth, much less professed to have a proof of it in our power. We simply showed by the development of the universally received notion of morality that an autonomy of the will is inevitably connected with it, or rather is its foundation. Whoever then holds morality to be anything real, and not a chimerical idea without any truth, must likewise admit the principle of it that is here assigned. This section then, like the first, was merely analytical. Now to prove that morality is no creation of the brain, which it cannot be if the categorical imperative and with it the autonomy of the will is true, and as an a priori principle absolutely necessary, this supposes the POSSIBILITY OF A SYNTHETIC USE OF PURE PRACTICAL REASON, which however we cannot venture on without first giving a critical examination of this faculty of reason. In the concluding section we shall give the principle outlines of this critical examination as far as is sufficient for our purpose.
THIRD SECTION
TRANSITION FROM THE METAPHYSIC OF MORALS TO THE CRITIQUE OF PURE PRACTICAL REASOH
The Concept of Freedom is the Key that explains the Autonomy of the
Will
The WILL is a kind of causality belonging to living beings in so far as they are rational, and FREEDOM would be this property of such causality that it can be efficient, independently on foreign causes DETERMINING it; just as PHYSICAL NECESSITY is the property that the causality of all irrational beings has of being determined to activity by the influence of foreign causes.
The preceding definition of freedom is NEGATIVE, and therefore unfruitful for the discovery of its essence; but it leads to a POSITIVE conception which is so much the more full and fruitful Since the conception of causality involves that of laws, according to which, by something that we call cause, something else, namely, the effect, must be produced [laid down]; [Footnote: (Gesetzt.-There is in the original a play on the etymology of Gesetz, which does not admit of reproduction in English. It must be confessed that without it the statement is not self-evident.)] hence, although freedom is not a property of the will depending on physical laws, yet it is not for that reason lawless; on the contrary it must be a causality acting according to immutable laws, but of a peculiar kind; otherwise a free will would be an absurdity. Physical necessity is a heteronomy of the efficient causes, for every effect is possible only according to this law, that something else determines the efficient cause to exert its causality. What else then can freedom of the will be but autonomy, that is the property of the will to be a law to itself? But the proposition: The will is in every action a law to itself, only expresses the principle, to act on no other maxim than that which can also have as an object itself as a universal law. Now this is precisely the formula of the categorical imperative and is the principle of morality, so that a free will and a will subject to moral laws are one and the same.
On the hypothesis then of freedom of the will, morality together with its principle follows from it by mere analysis of the conception. However the latter is still a synthetic proposition; viz., an absolutely good will is that whose maxim can always include itself regarded as a universal law; for this property of its maxim can never be discovered by analysing the conception of an absolutely good will. Now such synthetic propositions are only possible in this way: that the two cognitions are connected together by their union with a third in which they are both to be found. The POSITIVE concept of freedom furnishes this third cognition, which cannot, as with physical causes, be the nature of the sensible world (in the concept of which we find conjoined the concept of something in relation as cause to SOMETHING ELSE as effect). We cannot now at once show what this third is to which freedom points us, and of which we have an idea a priori, nor can we make intelligible how the concept of freedom is shown to be legitimate from principles of pure practical reason, and with it the possibility of a categorical imperative; but some further preparation is required.
Freedom must be presupposed as a Property of the Will of all
Rational Beings
It is not enough to predicate freedom of our own will, from whatever reason, if we have not sufficient grounds for predicating the same of all rational beings. For as morality serves as a law for us only because we are RATIONAL BEINGS, it must also hold for all rational beings; and as it must be deduced simply from the property of freedom, it must be shown that freedom also is a property of all rational beings. It is not enough then to prove it from certain supposed experiences of human nature (which indeed is quite impossible, and it can only be shown a priori), but we must show that it belongs to the activity of all rational beings endowed with a will. Now I say every being that cannot act except UNDER THE IDEA OF FREEDOM is just for that reason in a practical point of view really free, that is to say, all laws which are inseparably connected with freedom have the same force for him as if his will had been shown to be free in itself by a proof theoretically conclusive. [Footnote: I adopt this method of assuming freedom merely AS AN IDEA which rational beings suppose in their actions, in order to avoid the necessity of proving it in its theoretical aspect also. The former is sufficient for my purpose; for even though the speculative proof should not be made out, yet a being that cannot act except with the idea of freedom is bound by the same laws that would oblige a being who was actually free. Thus we can escape here from the onus which presses on the theory. (Compare Butler's treatment of the question of liberty in his "Analogy," part I., ch. vi.)] Now I affirm that we must attribute to every rational being which has a will that it has also the idea of freedom and acts entirely under this idea. For in such a being we conceive a reason that is practical, that is, has causality in reference to its objects. Now we cannot possibly conceive a reason consciously receiving a bias from any other quarter with respect to its judgments, for then the subject would ascribe the determination of its judgment not to its own reason, but to an impulse. It must regard itself as the author of its principles independent on foreign influences. Consequently as practical reason or as the will of a rational being it must regard itself as free, that is to say, the will of such a being cannot be a will of its own except under the idea of freedom. This idea must therefore in a practical point of view be ascribed to every rational being.