The Critique of Practical Reason · Immanuel Kant
IV. The Immortality of the Soul as a Postulate of
Pure Practical Reason. The realization of the summum bonum in the world is the necessary object of a will determinable by the moral law. But in this will the perfect accordance of the mind with the moral law is the supreme condition of the summum bonum. This then must be possible, as well as its object, since it is contained in the command to promote the latter. Now, the perfect accordance of the will with the moral law is holiness, a perfection of which no rational being of the sensible world is capable at any moment of his existence. Since, nevertheless, it is required as practically necessary, it can only be found in a progress in infinitum towards that perfect accordance, and on the principles of pure practical reason it is necessary to assume such a practical progress as the real object of our will. {BOOK_2|CHAPTER_2 ^paragraph 35} Now, this endless progress is only possible on the supposition of an endless duration of the existence and personality of the same rational being (which is called the immortality of the soul). The summum bonum, then, practically is only possible on the supposition of the immortality of the soul; consequently this immortality, being inseparably connected with the moral law, is a postulate of pure practical reason (by which I mean a theoretical proposition, not demonstrable as such, but which is an inseparable result of an unconditional a priori practical law.
This principle of the moral destination of our nature, namely, that it is only in an endless progress that we can attain perfect accordance with the moral law, is of the greatest use, not merely for the present purpose of supplementing the impotence of speculative reason, but also with respect to religion. In default of it, either the moral law is quite degraded from its holiness, being made out to be indulgent and conformable to our convenience, or else men strain their notions of their vocation and their expectation to an unattainable goal, hoping to acquire complete holiness of will, and so they lose themselves in fanatical theosophic dreams, which wholly contradict self-knowledge. In both cases the unceasing effort to obey punctually and thoroughly a strict and inflexible command of reason, which yet is not ideal but real, is only hindered. For a rational but finite being, the only thing possible is an endless progress from the lower to higher degrees of moral perfection. The Infinite Being, to whom the condition of time is nothing, sees in this to us endless succession a whole of accordance with the moral law; and the holiness which his command inexorably requires, in order to be true to his justice in the share which He assigns to each in the summum bonum, is to be found in a single intellectual intuition of the whole existence of rational beings. All that can be expected of the creature in respect of the hope of this participation would be the consciousness of his tried character, by which from the progress he has hitherto made from the worse to the morally better, and the immutability of purpose which has thus become known to him, he may hope for a further unbroken continuance of the same, however long his existence may last, even beyond this life, * and thus he may hope, not indeed here, nor in any imaginable point of his future existence, but only in the endlessness of his duration (which God alone can survey) to be perfectly adequate to his will (without indulgence or excuse, which do not harmonize with justice).
Happiness is the condition of a rational being in the world with whom everything goes according to his wish and will; it rests, therefore, on the harmony of physical nature with his whole end and likewise with the essential determining principle of his will. Now the moral law as a law of freedom commands by determining principles, which ought to be quite independent of nature and of its harmony with our faculty of desire (as springs). But the acting rational being in the world is not the cause of the world and of nature itself. There is not the least ground, therefore, in the moral law for a necessary connection between morality and proportionate happiness in a being that belongs to the world as part of it, and therefore dependent on it, and which for that reason cannot by his will be a cause of this nature, nor by his own power make it thoroughly harmonize, as far as his happiness is concerned, with his practical principles. Nevertheless, in the practical problem of pure reason, i.e., the necessary pursuit of the summum bonum, such a connection is postulated as necessary: we ought to endeavour to promote the summum bonum, which, therefore, must be possible.
Accordingly, the existence of a cause of all nature, distinct from nature itself and containing the principle of this connection, namely, of the exact harmony of happiness with morality, is also postulated. Now this supreme cause must contain the principle of the harmony of nature, not merely with a law of the will of rational beings, but with the conception of this law, in so far as they make it the supreme determining principle of the will, and consequently not merely with the form of morals, but with their morality as their motive, that is, with their moral character. Therefore, the summum bonum is possible in the world only on the supposition of a Supreme Being having a causality corresponding to moral character. Now a being that is capable of acting on the conception of laws is an intelligence (a rational being), and the causality of such a being according to this conception of laws is his will; therefore the supreme cause of nature, which must be presupposed as a condition of the summum bonum is a being which is the cause of nature by intelligence and will, consequently its author, that is God. It follows that the postulate of the possibility of the highest derived good (the best world) is likewise the postulate of the reality of a highest original good, that is to say, of the existence of God. Now it was seen to be a duty for us to promote the summum bonum; consequently it is not merely allowable, but it is a necessity connected with duty as a requisite, that we should presuppose the possibility of this summum bonum; and as this is possible only on condition of the existence of God, it inseparably connects the supposition of this with duty; that is, it is morally necessary to assume the existence of God.
It must be remarked here that this moral necessity is subjective, that is, it is a want, and not objective, that is, itself a duty, for there cannot be a duty to suppose the existence of anything (since this concerns only the theoretical employment of reason). Moreover, it is not meant by this that it is necessary to suppose the existence of God as a basis of all obligation in general (for this rests, as has been sufficiently proved, simply on the autonomy of reason itself). What belongs to duty here is only the endeavour to realize and promote the summum bonum in the world, the possibility of which can therefore be postulated; and as our reason finds it not conceivable except on the supposition of a supreme intelligence, the admission of this existence is therefore connected with the consciousness of our duty, although the admission itself belongs to the domain of speculative reason. Considered in respect of this alone, as a principle of explanation, it may be called a hypothesis, but in reference to the intelligibility of an object given us by the moral law (the summum bonum), and consequently of a requirement for practical purposes, it may be called faith, that is to say a pure rational faith, since pure reason (both in its theoretical and practical use) is the sole source from which it springs.
The Stoics, on the contrary, had chosen their supreme practical principle quite rightly, making virtue the condition of the summum bonum; but when they represented the degree of virtue required by its pure law as fully attainable in this life, they not only strained the moral powers of the man whom they called the wise beyond all the limits of his nature, and assumed a thing that contradicts all our knowledge of men, but also and principally they would not allow the second element of the summum bonum, namely, happiness, to be properly a special object of human desire, but made their wise man, like a divinity in his consciousness of the excellence of his person, wholly independent of nature (as regards his own contentment); they exposed him indeed to the evils of life, but made him not subject to them (at the same time representing him also as free from moral evil). They thus, in fact, left out the second element of the summum bonum namely, personal happiness, placing it solely in action and satisfaction with one's own personal worth, thus including it in the consciousness of being morally minded, in which they Might have been sufficiently refuted by the voice of their own nature.
The doctrine of Christianity, * even if we do not yet consider it as a religious doctrine, gives, touching this point, a conception of the summum bonum (the kingdom of God), which alone satisfies the strictest demand of practical reason. The moral law is holy (unyielding) and demands holiness of morals, although all the moral perfection to which man can attain is still only virtue, that is, a rightful disposition arising from respect for the law, implying consciousness of a constant propensity to transgression, or at least a want of purity, that is, a mixture of many spurious (not moral) motives of obedience to the law, consequently a self-esteem combined with humility. In respect, then, of the holiness which the Christian law requires, this leaves the creature nothing but a progress in infinitum, but for that very reason it justifies him in hoping for an endless duration of his existence. The worth of a character perfectly accordant with the moral law is infinite, since the only restriction on all possible happiness in the judgement of a wise and all powerful distributor of it is the absence of conformity of rational beings to their duty.
But the moral law of itself does not promise any happiness, for according to our conceptions of an order of nature in general, this is not necessarily connected with obedience to the law. Now Christian morality supplies this defect (of the second indispensable element of the summum bonum) by representing the world in which rational beings devote themselves with all their soul to the moral law, as a kingdom of God, in which nature and morality are brought into a harmony foreign to each of itself, by a holy Author who makes the derived summum bonum possible. Holiness of life is prescribed to them as a rule even in this life, while the welfare proportioned to it, namely, bliss, is represented as attainable only in an eternity; because the former must always be the pattern of their conduct in every state, and progress towards it is already possible and necessary in this life; while the latter, under the name of happiness, cannot be attained at all in this world (so far as our own power is concerned), and therefore is made simply an object of hope. Nevertheless, the Christian principle of morality itself is not theological (so as to be heteronomy), but is autonomy of pure practical reason, since it does not make the knowledge of God and His will the foundation of these laws, but only of the attainment of the summum bonum, on condition of following these laws, and it does not even place the proper spring of this obedience in the desired results, but solely in the conception of duty, as that of which the faithful observance alone constitutes the worthiness to obtain those happy consequences.
When I give the name idea to a perfection to which nothing adequate can be given in experience, it does not follow that the moral ideas are thing transcendent, that is something of which we could not even determine the concept adequately, or of which it is uncertain whether there is any object corresponding to it at all, as is the case with the ideas of speculative reason; on the contrary, being types of practical perfection, they serve as the indispensable rule of conduct and likewise as the standard of comparison. Now if I consider Christian morals on their philosophical side, then compared with the ideas of the Greek schools, they would appear as follows: the ideas of the Cynics, the Epicureans, the Stoics, and the Christians are: simplicity of nature, prudence, wisdom, and holiness. In respect of the way of attaining them, the Greek schools were distinguished from one another thus that the Cynics only required common sense, the others the path of science, but both found the mere use of natural powers sufficient for the purpose. Christian morality, because its precept is framed (as a moral precept must be) so pure and unyielding, takes from man all confidence that he can be fully adequate to it, at least in this life, but again sets it up by enabling us to hope that if we act as well as it is in our power to do, then what is not in our power will come in to our aid from another source, whether we know how this may be or not. Aristotle and Plato differed only as to the origin of our moral conceptions.
Hence also morality is not properly the doctrine how we should make ourselves happy, but how we should become worthy of happiness. It is only when religion is added that there also comes in the hope of participating some day in happiness in proportion as we have endeavoured to be not unworthy of it. A man is worthy to possess a thing or a state when his possession of it is in harmony with the summum bonum. We can now easily see that all worthiness depends on moral conduct, since in the conception of the summum bonum this constitutes the condition of the rest (which belongs to one's state), namely, the participation of happiness. Now it follows from this that morality should never be treated as a doctrine of happiness, that is, an instruction how to become happy; for it has to do simply with the rational condition (conditio sine qua non) of happiness, not with the means of attaining it. But when morality has been completely expounded (which merely imposes duties instead of providing rules for selfish desires), then first, after the moral desire to promote the summum bonum (to bring the kingdom of God to us) has been awakened, a desire founded on a law, and which could not previously arise in any selfish mind, and when for the behoof of this desire the step to religion has been taken, then this ethical doctrine may be also called a doctrine of happiness because the hope of happiness first begins with religion only.
We can also see from this that, when we ask what is God's ultimate end in creating the world, we must not name the happiness of the rational beings in it, but the summum bonum, which adds a further condition to that wish of such beings, namely, the condition of being worthy of happiness, that is, the morality of these same rational beings, a condition which alone contains the rule by which only they can hope to share in the former at the hand of a wise Author. For as wisdom, theoretically considered, signifies the knowledge of the summum bonum and, practically, the accordance of the will with the summum bonum, we cannot attribute to a supreme independent wisdom an end based merely on goodness. For we cannot conceive the action of this goodness (in respect of the happiness of rational beings) as suitable to the highest original good, except under the restrictive conditions of harmony with the holiness * of his will. Therefore, those who placed the end of creation in the glory of God (provided that this is not conceived anthropomorphically as a desire to be praised) have perhaps hit upon the best expression. For nothing glorifies God more than that which is the most estimable thing in the world, respect for his command, the observance of the holy duty that his law imposes on us, when there is added thereto his glorious plan of crowning such a beautiful order of things with corresponding happiness. If the latter (to speak humanly) makes Him worthy of love, by the former He is an object of adoration. Even men can never acquire respect by benevolence alone, though they may gain love, so that the greatest beneficence only procures them honour when it is regulated by worthiness.
VI. Of the Postulates of Pure Practical Reason Generally. {BOOK_2|CHAPTER_2 ^paragraph 60} They all proceed from the principle of morality, which is not a postulate but a law, by which reason determines the will directly, which will, because it is so determined as a pure will, requires these necessary conditions of obedience to its precept. These postulates are not theoretical dogmas but, suppositions practically necessary; while then they do [not] extend our speculative knowledge, they give objective reality to the ideas of speculative reason in general (by means of their reference to what is practical), and give it a right to concepts, the possibility even of which it could not otherwise venture to affirm. These postulates are those of immortality, freedom positively considered (as the causality of a being so far as he belongs to the intelligible world), and the existence of God. The first results from the practically necessary condition of a duration adequate to the complete fulfilment of the moral law; the second from the necessary supposition of independence of the sensible world, and of the faculty of determining one's will according to the law of an intelligible world, that is, of freedom; the third from the necessary condition of the existence of the summum bonum in such an intelligible world, by the supposition of the supreme independent good, that is, the existence of God.
Thus the fact that respect for the moral law necessarily makes the summum bonum an object of our endeavours, and the supposition thence resulting of its objective reality, lead through the postulates of practical reason to conceptions which speculative reason might indeed present as problems, but could never solve. Thus it leads: 1. To that one in the solution of which the latter could do nothing but commit paralogisms (namely, that of immortality), because it could not lay hold of the character of permanence, by which to complete the psychological conception of an ultimate subject necessarily ascribed to the soul in self-consciousness, so as to make it the real conception of a substance, a character which practical reason furnishes by the postulate of a duration required for accordance with the moral law in the summum bonum, which is the whole end of practical reason. 2. It leads to that of which speculative reason contained nothing but antinomy, the solution of which it could only found on a notion problematically conceivable indeed, but whose objective reality it could not prove or determine, namely, the cosmological idea of an intelligible world and the consciousness of our existence in it, by means of the postulate of freedom (the reality of which it lays down by virtue of the moral law), and with it likewise the law of an intelligible world, to which speculative reason could only point, but could not define its conception. 3. What speculative reason was able to think, but was obliged to leave undetermined as a mere transcendental ideal, viz., the theological conception of the first Being, to this it gives significance (in a practical view, that is, as a condition of the possibility of the object of a will determined by that law), namely, as the supreme principle of the summum bonum in an intelligible world, by means of moral legislation in it invested with sovereign power.
Ideas discussed in this chapter
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