Critique of Pure Reason

by Immanuel Kant

  Canon of Pure Reason

  Section II

  Of the Ideal of the Summum Bonum as determining the Ultimate Aim of Pure Reason

  Reason, in its speculative employment, conducted us through the field of experience, and, as it could find no perfect satisfaction there, from thence to speculative ideas which, however, in the end conducted us back again to experience, and thus fulfilled their purpose in a manner which, though useful, was not at all in accordance with our expectation. We may now have one more trial, namely, to see whether pure reason may be met with in practical use also, and whether thus it may lead to ideas which realise the highest aims of pure reason as we have just stated them, and whether therefore from the point of view of its practical interest, reason may not be able to grant us what it entirely refused to do with regard to its speculative interest.

  The whole interest of my reason, whether speculative or practical, is concentrated in the three following questions:—

  1. What can I know?

  2. What should I do?

  3. What may I hope?

  The first question is purely speculative. We have, as I flatter myself, exhausted all possible answers, and found, at last, that with which no doubt reason must be satisfied, and, except with regard to the practical, has just cause to be satisfied. We remained, however, as far removed from the two great ends to which the whole endeavour of pure reason was really directed as if we had consulted our ease and declined the whole task from the very beginning. So far then as knowledge is concerned, so much is certain and clear that, with regard to these two problems, knowledge can never fall to our lot.

  The second question is purely practical. As such it may come within the cognisance of pure reason, but is, even then, not transcendental, but moral, and cannot, consequently, occupy our criticism by itself.

  The third question, namely, what may I hope for, if I do what I ought to do? is at the same time practical and theoretical, the practical serving as a guidance to the answer to the theoretical and, in its highest form, speculative question; for all hoping is directed towards happiness and is, with regard to practical interests and the law of morality, the same as knowing and the law of nature, with regard to the theoretical cognition of things. The former arrives at last at a conclusion that something is (which determines the last possible aim) because something ought to take place; the latter, that something is (which operates as the highest cause) because something does take place.

  Happiness is the satisfaction of all our desires, extensively, in regard to their manifoldness, intensively, in regard to their degree, and protensively, in regard to their duration. The practical law, derived from the motive of happiness, I call pragmatical (rule of prudence); but the law, if there is such a law, which has no other motive but to deserve to be happy, I call moral (law of morality). The former advises us what we have to do, if we wish to possess happiness; the latter dictates how we ought to conduct ourselves in order to deserve happiness. The former is founded on empirical principles, for I cannot know, except by experience, what desires there are which are to be satisfied, nor what are the natural means of satisfying them. The second takes no account of desires and the natural means of satisfying them, and regards only the freedom of any rational being and the necessary conditions under which alone it can harmonise with the distribution of happiness according to principles. It can therefore be based on mere ideas of pure reason, and known a priori. I assume that there really exist pure moral laws which entirely a priori (without regard to empirical motives, that is, happiness) determine the use of the freedom of any rational being, both with regard to what has to be done and what has not to be done, and that these laws are imperative absolutely (not hypothetically only on the supposition of other empirical ends), and therefore in every respect necessary. I feel justified in assuming this, by appealing, not only to the arguments of the most enlightened moralists, but also to the moral judgment of every man, if he only tries to conceive such a law clearly.

  Pure reason, therefore, contains not indeed in its speculative, yet in its practical, or, more accurately, its moral employment, principles of the possibility of experience, namely, of such actions as might be met with in the history of man according to moral precepts. For as reason commands that such actions should take place, they must be possible, and a certain kind of systematical unity also, namely, the moral must be possible; while it was impossible to prove the systematical unity of nature according to the speculative principles of reason. For reason, no doubt, possesses causality with respect to freedom in general, but not with respect to the whole of nature, and moral principles of reason may indeed produce free actions, but not laws of nature. Consequently, the principles of pure reason possess objective reality in their practical and more particularly in their moral employment.

  I call the world, in so far as it may be in accordance with all moral laws which, by virtue of the freedom of rational beings it may, and according to the necessary laws of morality it ought to be, a moral world. As here we take no account of all conditions (aims) and even of all impediments to morality (the weakness or depravity of human nature), this world is conceived as an intelligible world only. It is, therefore, so far a mere idea, though a practical idea, which can and ought really to exercise its influence on the sensible world in order to bring it, as far as possible, into conformity with that idea. The idea of a moral world has therefore objective reality, not as referring to an object of intelligible intuition (which we cannot even conceive), but as referring to the sensible world, conceived as an object of pure reason in its practical employment, and as a corpus mysticum of rational beings dwelling in it, so far as their free-will, placed under moral laws, possesses a thorough systematical unity both with itself and with the freedom of everybody else.

  The answer, therefore, of the first of the two questions of pure reason with reference to practical interests, is this, 'do that which will render thee deserving of happiness.' The second question asks, how then, if I conduct myself so as to be deserving of happiness, may I hope thereby to obtain happiness? The answer to this question depends on this, whether the principles of pure reason which a priori prescribe the law, necessarily also connect this hope with it?

  I say, then, that just as the moral principles are necessary according to reason in its practical employment, it is equally necessary according to reason in its theoretic employment to assume that everybody has reason to hope to obtain happiness in the same measure in which he has rendered himself deserving of it in his conduct; and that, therefore, the system of morality is inseparably, though only in the idea of pure reason, connected with that of happiness.

  In an intelligible, that is, in a moral world, in conceiving which we take no account of any of the impediments to morality (desires, etc.), such a system, in which happiness is proportioned to morality, may even be considered as necessary, because freedom, as repelled or restrained by the moral law, is itself the cause of general happiness, and rational beings therefore themselves, under the guidance of such principles, the authors of the permanent well-being of themselves, and at the same time of others. But such a system of self-rewarding morality is an idea only, the realisation of which depends on everybody doing what he ought to do, that is, on all actions of reasonable beings being so performed as if they sprang from one supreme will, comprehending within itself or under itself all private wills. But, as the moral law remains binding upon every one in the use of his freedom, even if others do not conform to that law, it is impossible that either the nature of things in the world, or the causality of the actions themselves, or their relation to morality, should determine in what relation the consequences of such actions should stand to happiness. If, therefore, we take our stand on nature only, the necessary connection of a hope of happiness with the unceasing endeavour of rendering oneself deserving of happiness, cannot be known by reason, but can only be hoped for, if a highest reason, which rules according to moral laws, is accepted at the same time as the cause of nature.


  I call the idea of such an intelligence in which the most perfect moral will, united with the highest blessedness, is the cause of all happiness in the world, so far as it corresponds exactly with morality, that is, the being worthy of happiness, the ideal of the supreme good. It is, therefore, in the ideal only of the supreme original good that pure reason can find the ground of the practically necessary connection of both elements of the highest derivative good, namely, of an intelligible, that is, moral world. As we are bound by reason to conceive ourselves as belonging necessarily to such a world, though the senses present us with nothing but a world of phenomena, we shall have to accept the other world as the result of our conduct in this world of sense (in which we see no such connection between goodness and happiness), and therefore as to us a future world. Hence it follows that God and a future life are two suppositions which, according to the principles of pure reason, cannot be separated from the obligation which that very reason imposes on us.

  Morality, by itself, constitutes a system, but not so happiness, unless it is distributed in exact proportion to morality. This, however, is possible in an intelligible world only under a wise author and ruler. Such a ruler, together with life in such a world, which we must consider as future, reason compels us to admit, unless all moral laws are to be considered as idle dreams, because, without that supposition, the necessary consequences, which the same reason connects with these laws, would be absent. Hence everybody looks upon moral laws as commands, which they could not be if they did not connect a priori adequate consequences with their rules, and carried with them both promises and threats. Nor could they do this unless they rested on a necessary Being, as the supreme good, which alone can render the unity of such a design possible.

  Leibniz called the world, if we have regard only to the rational beings in it, and their mutual relations according to moral laws and under the government of the supreme good, the kingdom of grace, distinguishing it from the kingdom of nature, in which these beings, though standing under moral laws, expect no other consequences from their conduct but such as follow according to the course of nature of our sensible world. To view ourselves as belonging to the kingdom of grace, in which all happiness awaits us, except in so far as we have diminished our share in it through our unworthiness of being happy, is a practically necessary idea of reason.

  Practical laws, in so far as they become at the same time subjective grounds of actions, that is, subjective principles, are called maxims. The criticism of morality, with regard to its purity and its results, takes place according to ideas, the practical observance of its laws, according to maxims.

  It is necessary that the whole course of our life should be subject to moral maxims; but this is impossible, unless reason connects with the moral law, which is a mere idea, an efficient cause, which assigns to all conduct, in accordance with the moral law, an issue accurately corresponding to our highest aims, whether in this or in another life. Thus without a God and without a world, not visible to us now, but hoped for, the glorious ideas of morality are indeed objects of applause and admiration, but not springs of purpose and action, because they fail to fulfil all the aims which are natural to every rational being, and which are determined a priori by the same pure reason, and therefore necessary.

  Our reason does by no means consider happiness alone as the perfect good. It does not approve of it (however much inclination may desire it), except as united with desert, that is, with perfect moral conduct. Nor is morality alone, and with it mere desert of being happy, the perfect good. To make it perfect, he who has conducted himself as not unworthy of happiness, must be able to hope to participate in it. Even if freed from all private views and interests reason, were it to put itself in the place of a being that had to distribute all happiness to others, could not judge otherwise; because in the practical idea both elements are essentially connected, though in such a way that our participation in happiness should be rendered possible by the moral character as a condition, and not conversely the moral character by the prospect of happiness. For, in the latter case, the character would not be moral, nor worthy therefore of complete happiness; a happiness which, in the eyes of reason, admits of no limitation but such as arises from our own immoral conduct.

  Happiness, therefore, in exact proportion with the morality of rational beings who are made worthy of happiness by it, constitutes alone the supreme good of a world into which we must necessarily place ourselves according to the commands of pure but practical reason. But this is an intelligible world only, and a sensible world never promises us such a systematical unity of ends as arising from the nature of things. Nor is the reality of this unity founded on anything but the admission of a supreme original good, so that independent reason, equipped with all the requirements of a supreme cause, founds, maintains, and completes, according to the most perfect design, the universal order of things which, in the world of sense, is almost completely hidden from our sight.

  This moral theology has this peculiar advantage over speculative theology, that it leads inevitably to the concept of a sole, most perfect, and rational first Being, to which speculative theology does not even lead us on, on objective grounds, much less give us a conviction of it. For neither in transcendental nor in natural theology, however far reason may carry us on, do we find any real ground for admitting even one sole being which we should be warranted in placing before all natural causes and on which we might make them in all respects to depend. On the other hand, if, from the point of view of moral unity as a necessary law of the universe, we consider what cause alone could give to it its adequate effect, and therefore its binding force with regard to ourselves, we find that it must be one sole supreme will which comprehends all these laws within itself. For how with different wills should we find complete unity of ends? That will must be omnipotent, in order that the whole of nature and its relation to morality and the world may be subject to it; omniscient, that it may know the most secret springs of our sentiments and their moral worth; omnipresent, that it may be near for supplying immediately all that is required by the highest interests of the world; eternal, that this harmony of nature and freedom may never fail, and so on.

  But this systematical unity of ends in this world of intelligence which, if looked upon as mere nature, may be called a sensible world only, but which, if considered as a system of freedom, may be called an intelligible, that is, a moral world (regnum gratiae), leads inevitably also to the admission of a unity of design in all things which constitute this great universe according to general natural laws, just as the former (unity) was according to general and necessary laws of morality. In this way practical and speculative reason become united. The world must be represented as having originated from an idea, if it is to harmonise with that employment of reason without which we should consider ourselves unworthy of reason, namely, with its moral employment, which is founded entirely on the idea of the supreme good. In this way the study of nature tends to assume the form of a teleological system, and becomes in its widest extension physico-theology. And this, as it starts from the moral order as a unity founded on the essence of freedom, and not accidentally brought about by external commands, traces the design of nature to grounds which must be inseparably connected a priori with the internal possibility of things, and leads thus to a transcendental theology, which takes the ideal of the highest ontological perfection as the principle of systematical unity which connects all things according to general and necessary laws of nature, because they all have their origin in the absolute necessity of the one original Being.

  What use can we make of our understanding, even in respect to experience, if we have not aims before us? The highest aims, however, are those of morality, and these we can only know by means of pure reason. Even with their help and guidance, however, we could make no proper use of the knowledge of nature, unless nature itself had established a unity of design: for without this we should ourselves have no reason, because there would be no school for it, nor a
ny culture derived from objects which supply the material for such concepts. This unity of design is necessary and founded on the essence of free-will, which must, therefore, as containing the condition of its application in concreto, be so likewise; so that, in reality, the transcendental development of the knowledge obtained by our reason would be, not the cause, but only the effect of that practical order and design which pure reason imposes upon us.

  We find therefore in the history of human reason also that, before the moral concepts were sufficiently purified and refined, and before the systematical unity of the ends was clearly understood, according to such concepts and in accordance with necessary principles, the then existing knowledge of nature and even a considerable amount of the culture of reason in many other branches of science could only produce crude and vague conceptions of the Deity, or allow of an astonishing indifference with regard to that question. A greater cultivation of moral ideas, which became necessary through the extremely pure moral law of our religion, directed our reason to that object through the interest which it forced us to take in it, and without the help either of a more extended knowledge of nature, or of more correct and trustworthy transcendental views (which have been wanting in all ages). A concept of the Divine Being was elaborated which we now hold to be correct, not because speculative reason has convinced us of its correctness, but because it fully agrees with the moral principles of reason. And thus, after all, it is pure reason only, but pure reason in its practical employment, which may claim the merit of connecting with our highest interest that knowledge which pure speculation could only guess at without being able to establish its validity, and of having made it, not indeed a demonstrated dogma, but a supposition absolutely necessary to the most essential ends of reason.