“The Metaphysics of Morals” by Immanuel Kant (translated by Mary Gregor)

This is Kant’s take on a system of morality derived solely from a priori logic. “The concept of freedom is a pure rational concept, which for this very reason is transcendent for theoretical philosophy, that is, it is a concept such that no instance corresponding to it can be given in any possible experience…. But in reason’s practical use the concept of freedom proves its reality by practical principles, which are laws of a causality of pure reason for determining choice independently of any empirical conditions…. On this concept of freedom, which is positive (from a practical point of view), are based unconditional practical laws, which are called moral…. Moral laws are imperatives (commands or prohibitions) and indeed categorical (unconditional) imperatives…. By categorical imperatives certain actions are permitted or forbidden, that is, morally possible or impossible, while some of them or their opposites are morally necessary, that is, obligatory. For those actions, then, there arises the concept of a duty, observance or transgression of which is indeed connected with a pleasure or displeasure of a distinctive kind (moral feeling), although in practical laws of reason we take no account of these feelings.” Kant continues by stressing his concept of the categorical imperative, “A categorical (unconditional) imperative is one that represents an action as objectively necessary and makes it necessary not indirectly, through the representation of some end that can be attained by the action, but through the mere representation of this action itself (its form), and hence directly. No other practical doctrine can furnish instances of such imperatives than that which prescribes obligation (the doctrine of morals)…. A categorical imperative, because it asserts an obligation with respect to certain actions, is a morally practical law…. A categorical imperative is a law that either commands or prohibits, depending upon whether it represents as a duty the commission or omission of an action.” Finally, in Kant’s deontological system, people are always ends unto themselves and never just a means to another’s own ends. “For a human being can never be treated merely as a means to the purposes of another or be put among the objects of rights to things: his innate personality protects him from this, even though he can be condemned to lose his civil personality.”

Kant stresses the a priori nature of his moral system. “But in fact no moral principle is based, as people sometimes suppose, on any feeling whatsoever. Any such principle is really an obscurely thought metaphysics that is inherent in every human being because of his rational predisposition…. But his thought must go all the way back to the elements of metaphysics, without which no certitude or purity can be expected in the doctrine of virtue…. If one departs from this principle and begins with pathological or pure aesthetic or even moral feeling (with what is subjectively rather than objectively practical); if, that is, one begins with the matter of the will, the end, instead of with the form of the will, the law, in order to determine duties on this basis, then there will indeed be no metaphysical first principles of the doctrine of virtue…. After it has been made so clear that the principle of duty is derived from pure reason, one cannot help wondering how this principle could be reduced again to a doctrine of happiness.”

Furthermore, Kant parses out the difference between the external law that governs us, from the internal duties that must govern each individual unto himself. “In ancient times “ethics” signified the doctrine of morals (philosophia moralis) in general, which was also called the doctrine of duties. Later on it seemed better to reserve the name “ethics” for one part of moral philosophy, namely for the doctrine of those duties that do not come under external laws…. The very concept of duty is already the concept of a necessitation (constraint) of free choice through the law. This constraint may be an external constraint or a self-constraint. The moral imperative makes this constraint known through the categorical nature of its pronouncement (the unconditional ought)…. It is this self-constraint in opposite directions and its unavoidability that makes known the inexplicable property of freedom itself…. Only an end that is also a duty can be called a duty of virtue…. What essentially distinguishes a duty of virtue from a duty of right is that external constraint to the latter kind of duty is morally possible, whereas the former is based only on free self-constraint.”

Finally, Kant stresses that each man must know himself. “Know your heart – whether it is good or evil, whether the source of your actions is pure or impure, and what can be imputed to you as belonging originally to the substance of a human being or as derived (acquired or developed) and belonging to your moral condition…. Moral cognition of oneself, which seeks to penetrate into the depths (the abyss) of one’s heart which are quite difficult to fathom, is the beginning of all human wisdom…. Impartiality in appraising oneself in comparison with the law, and sincerity in acknowledging to oneself one’s inner moral worth or lack of worth are duties to oneself that follow directly from this first command to cognize oneself.”

“Groundwork of the Metaphysics of Morals” by Immanuel Kant (translated by Mary Gregor and Jens Timmermann)

This short treatise is Kant’s explication of his categorical imperative and the basis for his entire system of morals. He begins by explaining why morality is only linked with duty, “To do the action without any inclination, solely from duty; not until then does it have its genuine moral worth…. It is just there that the worth of character commences, which is moral and beyond all comparison the highest, namely that he be beneficent, not from inclination, but from duty.” He continues with a definition of duty, “Duty is the necessity of an action from respect for the law…. Only what is connected with my will merely as ground, never as effect, what does not serve my inclination, but outweighs it, or at least excludes it entirely from calculations when we make a choice, hence the mere law by itself, can be an object of respect and thus a command. Now, an action from duty is to separate off entirely the influence of inclination, and with it every object of the will; thus nothing remains for the will that could determine it except, objectively, the law and, subjectively, pure respect for this practical law…. I ought never to proceed except in such a way that I could also will that my maxim should become a universal law…. The necessity of my actions from pure respect for the practical law is that which constitutes duty, to which every other motivating ground must give way, because it is the condition of a will good in itself, whose worth surpasses everything.”

Kant continues by asserting that it is not consequentialism, but the inner motive of the individual that pertains to morality, “When moral worth is at issue what counts is not the actions, which one sees, but their inner principles, which one does not see.” He continues on the concept of the Will, “Only a rational being has the capacity to act according to the representation of laws, i.e. according to principles, or a will. Since reason is required for deriving actions from laws, the will is nothing other than practical reason…. The will is a capacity to choose only that which reason, independently of inclination, recognizes as practically necessary, i.e. as good.”

The categorical imperative is the central concept of Kant’s entire moral system. He begins, “The categorical imperative would be the one that represented an action as objectively necessary by itself, without reference to another end…. All imperatives are formulae for the determination of an action necessary according to the principle of a will that is good in some way…. The categorical imperative, which declares the action to be of itself objectively necessary without reference to any other purpose, i.e. even apart from any other end, holds as an apodictically practical principle…. There is therefore only a single categorical imperative, and it is this: act only according to that maxim through which you can at the same time will that it become a universal law…. So act as if the maxim of your action were to become by your will a universal law of nature.”

Next, Kant discusses treating every rational agent as an end. “A human being and generally every rational being exists as an end in itself, not merely as a means for the discretionary use for this or that will…. Rational beings are called persons, because their nature already marks them out as ends in themselves, i.e. as something that may not be used merely as a means…. These are therefore not merely subjective ends, the existence of which, as the effect of our action, has a worth for us; but rather objective ends, i.e. entities whose existence in itself is an end…. The ground of this principle is: a rational nature exists as an end in itself…. So act that you use humanity, in your own person as well as in the person of any other, always at the same time as an end, never merely as a means.” Kant connects this back with his categorical imperative, “Autonomy is thus the ground of the dignity of a human and of every rational nature…. The categorical imperative can also be expressed as follows: act according to maxims that can at the same time have as their object themselves as universal laws of nature. Such, then, is the formula of an absolutely good will…. A rational nature is distinguished from the others by this, that it sets itself an end.”

Kant might be described as the progenitor of German idealism. He talks of the world of appearances, where humans rely on their senses, and the world of things in themselves, defined through reason and understanding, but never quite grasped. “A human being cannot even—according to the acquaintance he has with himself by inner sensation—presume to cognize how he himself is in himself.” Kant concludes, “As a rational being, hence as one that belongs to the intelligible world, a human being can never think of the causality of his own will otherwise than under the idea of freedom…. When we think of ourselves as free, we transfer ourselves as members into the world of understanding, and cognize autonomy of the will, along with its consequence, morality; but if we think of ourselves as bound by duty we consider ourselves as belonging to the world of sense and yet at the same time to the world of understanding…. Categorical imperatives are possible, because the idea of freedom makes me a member of an intelligible world.”

“Critique of Judgment” by Immanuel Kant (translated by Werner S. Pluhar)

This is the final of Kant’s three treatises in his series of critiques. This book is divided into his critiques of the judgment of aesthetics and the judgment of teleology. But to start, Kant waxes on his theory of judgment, in general. For Kant, judgment is a bridge between the subjects of his first two critiques, “Judgment will bring about a transition from the pure cognitive power, i.e., from the domain of the concepts of nature, to the domain of the concept of freedom…. Judgment in general is the ability to think the particular as contained under the universal. If the universal (the rule, principle, law) is given, then judgment, which subsumes the particular under it, is determinative…. But if only the particular is given and judgment has to find the universal for it, then this power is merely reflective…. Determinative judgment, [which operates] under universal transcendental laws given by the understanding, is only subsumptive…. Reflective judgment, which is obligated to ascend from the particular in nature to the universal, requires a principle, which it cannot borrow from experience.”

Regarding the judgment of aesthetics, Kant begins, “What is merely subjective in the presentation of an object, i.e., what constitutes its reference to the subject and not to the object, is its aesthetic character…. When the senses present things outside me, the quality of the space in which these things are intuited is the merely subjective [feature] of my presentation of them (and because of this [feature] I cannot tell what such things may be as objects in themselves), and because of this subjective reference the object is moreover thought as merely appearance…. That subjective [feature] of a presentation which cannot at all become an element of cognition is the pleasure or displeasure connected with that presentation…. Not all aesthetic judgments are judgments of taste, which as such refer to the beautiful; but some of them arise from an intellectual feeling and as such refer to the sublime.”

Kant continues on about aesthetics, its subjectivity, and its necessary relationship back through the subject, “He will talk about the beautiful as if beauty were a characteristic of the object and the judgment were logical (namely, a cognition of the object through concepts of it), even though in fact the judgment is only aesthetic and refers the object’s presentation merely to the subject…. Since a judgment of taste involves the consciousness that all interest is kept out of it, it must also involve a claim to being valid for everyone, but without having a universality based on concepts. In other words, a judgment of taste must involve a claim to subjective universality…. In their logical quantity all judgments of taste are singular judgments…. There can be no rule by which someone could be compelled to acknowledge that something is beautiful. No one can use reasons or principles to talk us into a judgment on whether some garment, house, or flower is beautiful…. Beautiful is what, without a concept, is liked universally.”

Kant contrasts aesthetic beauty with the sublime, “Suppose we call something not only large, but large absolutely [schlechtin, absolut], in every respect (beyond all comparison), i.e., sublime. Clearly, in that case, we do not permit a standard adequate to it to be sought outside it, but only within it. It is a magnitude that is equal only to itself. It follows that the sublime must not be sought in things of nature, but must be sought solely in our ideas…. That is sublime in comparison with which everything else is small…. In order for the mind to be attuned to the feeling of the sublime, it must be receptive to ideas…. It is a dominance [Gewalt] that reason exerts over sensibility only for the sake of expanding it commensurately with reason’s own domain (the practical one) and letting it look outward toward the infinite, which for sensibility is an abyss. It is a fact that what is called sublime by us, having been prepared through culture, comes across as merely repellent to a person who in uncultured and lacking in the development of moral ideas…. We say that someone has no feeling if he remains unmoved in the presence of something we judge sublime.”

Kant returns to the concept of taste. “Taste lays claim merely to autonomy; but to make other people’s judgments the basis determining one’s own would be heteronomy…. Following by reference to precedent, rather than imitating, is the right term for any influence that products of an exemplary author may have on others…. Taste is precisely what stands most in need of examples regarding what has enjoyed the longest-lasting approval in the course of cultural progress…. Taste needs this because its judgment cannot be determined by concepts and precepts…. A judgment of taste, just as if it were merely subjective, cannot be determined by bases of proof…. The fact that others have liked something can never serve [the subject] as a basis for an aesthetic judgment.”

Finally, Kant discusses the nature of fine art. “What is essential in all fine art is the form that is purposive for our observation and judging, rather than the matter of sensation (i.e., charm or emotion). For the pleasure we take in purposive form is also culture, and it attunes the spirit to ideas…. Ideas, in the broadest sense, are presentations referred to an object according to a certain principle (subjective or objective) but are such that they can still never become cognition of an object. There are two kinds of ideas. One of these is referred to an intuition…. The other kind is referred to a concept…. Rational ideas are transcendent concepts; they differ from concepts of the understanding, which are called immanent because they can always be supplied with an experience…. An aesthetic idea cannot become cognition because it is an intuition (of the imagination) for which an adequate concept can never be found. A rational idea can never become cognition because it contains a concept (of the supersensible) for which no adequate intuition can ever be given…. I think we may call aesthetic ideas unexpoundable presentations of the imagination, and rational ideas indemonstrable concepts of reason.”

In the second section of his treatise, Kant lays out his critique of teleological judgment. He suggests, “Organized beings are the only beings in nature that, even when considered by themselves and apart from any relation to other things, must still be thought of as possible only as purposes of nature. It is these beings, therefore, which first give objective reality to the concept of a purpose that is a purpose of nature rather than a practical one, and which hence give natural science the basis for a teleology…. An organized product of nature is one in which everything is a purpose and reciprocally also a means. In such a product nothing is gratuitous, purposeless, or to be attributed to a blind natural mechanism.”

Kant concludes with man’s purposive role within nature, “Now in this world of ours there is only one kind of beings with a causality that is teleological, i.e., directed to purposes, but also so constituted that the law in terms of which these beings must determine their purposes is presented by these very beings as unconditioned and independent of conditions of nature, and yet necessary in itself. That being is man, but man considered as noumenon. Man is the only natural being in whom we can nonetheless cognize, as part of his own constitution, a supersensible ability (freedom) and even cognize the law and the object of this causality, the object that this being can set before itself as its highest purpose (the highest good in the world)…. His existence itself has the highest purpose within it…. Now if things in the world, which are dependent beings with regard to their existence, require a supreme cause that acts in terms of purposes, then man is the final purpose of creation…. Only in man, and even in him only as moral subject, do we find unconditioned legislation regarding purposes…. For the moral principle that determines us to action is supersensible. Hence it is the only possible [thing] in the order of purposes that is absolutely unconditioned as concerns nature, and hence alone qualifies man, the subject of morality, to be the final purpose of creation to which all of nature is subordinated.”

“Critique of Practical Reason” by Immanuel Kant (translated by Mary Gregor)

The second of Kant’s three critiques deals specifically with human agency and morality. Kant begins, “If, now, it is found that this rule is practically correct, then it is a law because it is a categorical imperative. Thus practical laws refer only to the will, without regard to what is attained by its causality…. In a practical law reason determines the will immediately, not by means of an intervening feeling of pleasure or displeasure, not even in this law; and that it can as pure reason be practical is what alone makes it possible for it to be lawgiving…. Pure reason is practical of itself alone and gives (to the human being) a universal law which we call the moral law…. Accordingly the moral law is for them an imperative that commands categorically because the law is unconditional; the relation of such a will to this law is dependence under the name of obligation, which signifies a necessitation, though only by reason and its objective law, to an action which is called duty.”

Kant contrasts duty with happiness. “The direct opposite of the principle of morality is the principle of one’s own happiness made the determining ground of the will…. The maxim of self-love (prudence) merely advises; the law of morality commands…. What duty is, is plain of itself to everyone, but what brings true lasting advantage, if this is to extend to the whole of one’s existence, is always veiled in impenetrable obscurity…. The moral law commands compliance from everyone, and indeed the most exact compliance. Appraising what is to be done in accordance with it must, therefore, not be so difficult that the most common and unpracticed understanding should not know how to go about it, even without worldly prudence…. To satisfy the categorical command of morality is within everyone’s power at all times; to satisfy the empirically conditioned precept of happiness is but seldom possible.”

Kant next contrasts morality with legality. “What is essential to any moral worth of actions is that the moral law determine the will immediately. If the determination of the will takes place conformably with the moral law but only by means of a feeling, of whatever kind, that has to be presupposed in order for the law to become a sufficient determining ground of the will, so that the action is not done for the sake of the law, then the action will contain legality indeed but not morality.” It is reason alone, not any feelings of the senses or outside pressures, that must determine the free will towards moral duty. “What is essential in every determination of the will by the moral law is that, as a free will—and so not only without the cooperation of sensible impulses but even with rejection of all of them and with infringement upon all inclinations insofar as they could be opposed to that law—it is determined solely by the law.”

Kant reiterates his categorical imperative that all rational agents must be treated by other agents as ends, in and of themselves, and not merely as means. “The moral law is holy (inviolable)…. A human being alone, and with him every rational creature, is an end in itself: by virtue of the autonomy of his freedom he is the subject of the moral law…. This subject is to be used never merely as a means but as at the same time an end…. In the order of ends the human being (and with him every rational being) is an end in itself, that is, can never be used merely as a means by anyone (not even by God) without being at the same time himself an end, and that humanity, in our person must, accordingly, be holy to ourselves: for he is the subject of the moral law.”

Kant squares his philosophy with his understanding of Christianity, “The moral law is holy (inflexible) and demands holiness of morals, although all the moral perfection that a human being can attain is still only virtue, that is, a disposition conformed with law from respect for law…. With respect to the holiness that the Christian law demands, nothing remains for a creature but endless progress…. The moral law of itself does not promise any happiness…. Holiness of morals is prescribed to them as a rule even in this life while the well-being proportioned to it, namely beatitude, is represented as attainable only in an eternity…. Morals is not properly the doctrine of how we are to make ourselves happy but of how we are to become worthy of happiness.”

Finally, Kant concludes, “Two things fill the mind with ever new and increasing admiration and reverence, the more often and more steadily one reflects on them: the starry heavens above me and the moral law within me. I do not need to search for them and merely conjecture them as though they were veiled in obscurity or in the transcendent region beyond my horizon; I see them before me and connect them immediately with the consciousness of my existence.”

“Critique of Pure Reason” by Immanuel Kant (translated by Werner S. Pluhar)

This book is a slog, but it rewards with a comprehensive system that pushes the bounds of pure reason to its limits. First, Kant has to define terms. “By critique of pure reason… I do not mean a critique of books and systems, but I mean the critique of our power of reason as such, in regard to all cognitions after which reason may strive independently of all experience. Hence I mean by it the decision as to whether a metaphysics as such is possible or impossible…. Transcendental philosophy is the system of all principles of pure reason…. But the critique is not yet that science itself, because it carries the analysis [of a priori concepts] only as far as is required for making a complete judgement about synthetic a priori cognition. The foremost goal in dividing such a science is this: no concepts whatever containing anything empirical must enter into this science.”

Kant next delineates the terms: experiences, intuitions, categories, concepts, and appearances. “All experience, besides containing the senses’ intuition through which something is given, does also contain a concept of an object that is given in intuition, or that appears. Accordingly, concepts of objects as such presumably underlie all experiential cognition as its a priori conditions. Hence presumably the objective validity of all categories, as a priori concepts, rests on the fact that through them alone is experience possible…. Hence the transcendental deduction of all a priori concepts has a principle to which the entire investigation must be directed: viz., the principle that these concepts must be cognized as a priori conditions for the possibility of experience…. If concepts serve as the objective basis for the possibility of experience, then—precisely because of this—they are necessary…. We have a pure imagination, as a basic power of the human soul which underlies a priori all cognition…. By means of this transcendental function of the imagination the two extreme ends, viz., sensibility and understanding, must necessarily cohere; for otherwise sensibility would indeed yield appearances, but would yield no objects of an empirical cognition, and hence no experience. Actual experience consists in apprehension of appearances, their association (reproduction), and thirdly their recognition; in this third [element] (which is the highest of these merely empirical elements of experience), such experience contains concepts, which make possible the formal unity of experience and with it all objective validity (truth) of empirical cognition. Now these bases of the recognition of the manifold, insofar as they concern merely the form of an experience as such, are the categories. Hence the categories underlie all formal unity in the synthesis of imagination…. We cannot think an object except through categories; we cannot cognize an object thought by us except through intuitions corresponding to those concepts. Now all our intuitions are sensible, and this [sensible] cognition is empirical insofar as its object is given. Empirical cognition, however, is experience. Consequently no cognition is possible for us a priori except solely of objects of possible experience…. As far as pure intuitions as well as pure concepts of understanding are concerned, they are elements of cognition that are found in us a priori.”

Next, Kant explicates the difference between analytic and synthetic judgements. “The supreme principle of all synthetic judgments is this: Every object is subject to the conditions necessary for synthetic unity of the manifold of intuition in a possible experience. Thus synthetic judgments are possible a priori if we refer the formal conditions of a priori intuition, the synthesis of imagination, and the necessary unity of this synthesis in a transcendental apperception to a possible experiential cognition as such.” Next, the difference between understanding and experience. “Everything that understanding draws from itself, rather than borrows from experience, it still has for the sake of nothing other than use in experience only. The principles of pure understanding—whether constitutive a priori (like the mathematical principles) or merely regulative (like the dynamical ones)—contain nothing but, as it were, the pure schema for possible experience. For experience has its unity solely from the synthetic unity that the understanding confers, originally and on its own, on the synthesis of imagination by reference to apperception; appearances, as data for a possible cognition, must a priori already have reference to, and be in harmony with, that synthetic unity. Now, these rules of understanding not only are true a priori; but, by containing the basis for the possibility of experience as the sum of all cognition wherein objects may be given to us, they are even the source of all truth.”

Kant moves on to cognition and reason. “All our cognition starts from the senses, proceeds from there to understanding, and ends with reason, beyond which there is found in us nothing higher to work on the material of intuition and bring it under the highest unity of thought…. There is of reason, as there is of understanding, a merely formal—i.e., logical—use, where reason abstracts from all content of cognition. But there is also a real use, where reason itself contains the origin of certain concepts and principles that it borrows neither from the senses nor from understanding…. We shall distinguish reason from understanding by calling it our power of principles…. I would, therefore, call cognition from principles only that cognition wherein I cognize the particular in the universal through concepts. Thus any syllogism is a form of deriving a cognition from a principle…. The understanding may be considered a power of providing unity of appearances by means of rules; reason is then the power of providing unity of the rules of understanding under principles. Hence reason initially never deals with experience or any object, but deals with the understanding in order to provide the understanding’s manifold cognitions with a priori unity through concepts…. The designation, concept of reason, even if considered provisionally, already shows that such a concept refuses to be confined within experience…. Concepts of reason serve for comprehending, whereas concepts of understanding serve for understanding (viz., perceptions). If concepts of reason contain the unconditioned, then they concern something to which all experience is subject but which itself is never an object of experience.”

Kant explains idealism. “The existence of all objects of outer senses is doubtful. I call this uncertainty the ideality of outer appearances, and the doctrine of this ideality is called idealism…. Only what is in ourselves can be perceived directly…. Therefore the existence of an actual object outside me (if this word is taken in its intellectual meaning) is never given straightforwardly in perception. Rather, perception is a modification of inner sense…. Hence, I cannot, in fact, perceive external things, but can only infer their existence from my inner perception…. Hence by an idealist we must mean, not someone who denies the existence of external objects of the senses, but someone who merely does not grant that this existence is cognized through direct perception, and who infers from this that we can never through any possible experience become completely certain of their actuality…. By transcendental idealism of all appearances I mean the doctrinal system whereby we regard them, one and all, as mere presentations and not things in themselves.”

Finally, Kant tentatively begins to pick through his theme, pure reason. “Apart from transcendental philosophy, there are two further pure rational sciences, the one having a merely speculative and the other a practical content: pure mathematics and pure morality.” Kant moves on to pure reason’s relationship with time and, therefore, causality and free will. “Pure reason, as a merely intelligible power, is not subjected to the form of time, nor consequently to the conditions of temporal succession. The causality of reason in its intelligible character by no means arises, or starts at a certain time, in order to produce an effect…. Of reason… one cannot say that the state wherein it determines the power of choice is preceded by another state wherein that state itself is determined…. Hence reason is the permanent condition of all the voluntary actions under which the human being appears. Each of these actions, even before it occurs, is predetermined in the human being’s empirical character. But in regard to the intelligible character, of which the empirical character is only the sensible schema, no before or after holds, and every action—regardless of its time relation to other appearances—is the direct effect of the intelligible character of pure reason…. In reason there is no antecedent state determining the subsequent state, and that reason therefore does not belong at all in the series of sensible conditions that make appearances necessary according to natural laws. Reason is present to, and is the same in, all actions of the human being in all circumstances of time…. Pure reason is in fact occupied with nothing but itself. Nor can it have any other business. For what are given to it are not objects for the unity of the experiential concept, but cognitions of understanding for the unity of the concept of reason, i.e., for the unity of coherence in a principle. The unity of reason is the unity of a system.”

Kant now circles back around to the reality of the transcendental and to the nature of God. “One asks, first, whether there is something that is distinct from the world and contains the basis of the world order and of the coherence thereof according to universal laws, then the answer is: without doubt. For the world is a sum of appearances; hence there must be some basis of these appearances that is transcendental, i.e., thinkable only for the pure understanding. If the question is, second, whether this being is substance, and of the greatest reality, and necessary, etc., then I answer that this question has no signification whatever. For all the categories through which I try to frame a concept of such an object have only an empirical use, and have no meaning whatever unless they are applied to objects of possible experience, i.e., to the world of sense.”

Kant explains the differences between philosophy and math. “Philosophical cognition is rational cognition from concepts. Mathematical cognition is rational cognition from the construction of concepts. But to construct a concept means to exhibit a priori the intuition corresponding to it. Hence construction of a concept requires a nonempirical intuition. Consequently this intuition, as intuition, is an individual object; but as the construction of a concept (a universal presentation), it must nonetheless express in the presentation its universal validity for all possible intuitions falling under the same concept…. Hence philosophical cognition contemplates the particular only in the universal. Mathematical cognition, on the other hand, contemplates the universal in the particular, and indeed even in the individual…. Hence the essential difference between these two kinds of rational cognition consists in this difference of form, and does not rest on the difference of their matter or [i.e.] objects…. Philosophy keeps to universal concepts only. Mathematics can accomplish nothing with the mere concept but hastens at once to intuition, in which it contemplates the concept in concreto, but yet not empirically; rather mathematics contemplates the concept only in an intuition that it exhibits a priori.” Kant also breaks down the difference in proofs of affirmation versus those of negation. “For no matter how modest and moderate someone may look who behaves toward the assertions of others in a merely declining and negating manner, yet as soon as he wants to make his objections hold as proofs of the opposite assertion, his claim is always just as haughty and imaginary as if he had adopted the affirming party and its assertion.”

Kant circles back to the relationship between appearances and pure reason. “In appearance, through which all objects are given to us, there are two components: the form of intuition (space and time), which can be cognized and determined completely a priori; and the matter (the physical [component] or content [of intuition], which signifies a something encountered in space and time and hence a something containing existence and corresponding to sensation…. You can say that properly speaking all life is intelligible only and not subjected to changes of time, and that it neither began through birth nor is ended through death; but that this life, on the other hand, is nothing but a mere appearance, i.e. a sensible presentation of the pure spiritual life, and the whole world of sense is a mere image hovering before our current way of cognizing, and like a dream has in itself no objective reality…. This is the fate of all assertions of pure reason: They [are synthetic propositions that] go beyond the conditions of all possible experience—the conditions outside of which no documentation of truth is anywhere to be found. But such assertions must nonetheless employ the laws of understanding; and these laws are determined merely for empirical use, yet without them no step can be taken in any synthetic thought.”

Kant, again, explicitly takes up the transcendental challenges of belief in God, free will, and the soul. “When I hear that an uncommon mind is supposed to have demonstrated away the freedom of the human will, the hope for a future life, and the existence of God, then I am eager to read his book; for in view of his talent I expect him to further my insights. That in fact he will have accomplished nothing of all this—this I already know beforehand with complete certainty…. Metaphysics has only three ideas as the proper purpose of its investigation—God, freedom, and immortality.... Everything else that this science deals with serves it only as a means for arriving at these ideas and at their reality.... Insight into these ideas would make theology, morality, and—through combination of the two—religion and hence the highest purposes of our existence dependent merely on our speculative power of reason and on nothing else.”

Kant concludes with a discussion on morality. “The moral law at least can rest on mere ideas of pure reason and thus be cognized a priori. I assume that there actually are pure moral laws that determine completely a priori (without regard to empirical motives, i.e., to happiness) the doing and the refraining, i.e., the use of the freedom of a rational being as such, and that these laws command absolutely (not merely hypothetically, on the presupposition of other empirical purposes) and are therefore necessary in every regard…. Hence pure reason contains—although not in its speculative use but still in a certain practical, viz., the moral, use—principles of the possibility of experience, viz., of the experience of such actions as could be encountered in accordance with moral precepts…. And hence a particular kind of systematic unity must be possible, viz., moral unity…. Accordingly, the principles of pure reason in its practical use—but specifically in its moral use—have objective reality…. The moral world is a mere idea; yet it is a practical idea that actually can and ought to have its influence on the world of sense…. The system of morality is linked inseparably—but only in the idea of pure reason—with the system of happiness…. The idea of such an intelligence wherein the morally most perfect will, combined with the highest bliss, is the cause of all happiness in the world, insofar as this happiness is exactly proportionate to one’s morality (as the worthiness to be happy), I call the ideal of the highest good…. Hence happiness, in exact balance with the morality of rational beings whereby these beings are worthy of happiness, alone amounts to the highest good of a world into which, according to the precepts of pure but practical reason, we must definitely transfer ourselves. That world, to be sure, is only an intelligible one; for the world of sense does not promise to us, as arising from the nature of things, such systematic unity of purposes. Moreover, the reality of that intelligible world cannot be based on anything other than the presupposition of a highest original good: a good where independent of reason, equipped with all the sufficiency of a supreme cause, establishes, preserves, and completes—according to the most perfect purposiveness—the order of things that is universal although very much concealed from us in the world of sense.”