The two parts of Kant’s moral religion

Abstract

Why in the Critique of Practical Reason is moral religion presented as a doctrine of the postulates of pure practical reason, of which Christian morality, considered as a philosophical doctrine, is an illustration, whereas in the Religion Within the Boundaries of Mere Reason moral religion is ultimately identified with a particular moral interpretation of the religious dogmas of Christianity? In this essay, I propose to answer this question by examining a thesis of Kant’s that has scarcely been considered. This is the thesis that, as with other philosophical disciplines, moral religion consists of a pure part and an applied part. The reasons for the bipartite division of moral religion—confirmed also by the findings of Kant’s third Critique—not only provide a direct, explicit, and maybe sufficient answer to the question posed, but also shed light on the role of Christianity in Kant’s conception of religion.

The problem of the diversity of the content of Kant’s moral religion

Both in the Critique of Practical Reason (1788) and in the Religion Within the Boundaries of Mere Reason (1793), Kant defines religion, i.e. natural or moral religion, as the recognition and observance of all our moral duties as divine commands (see KpV, AA 05: 129, RGV, AA 06: 84, 103, 153).¹ However, the way in which this definition is developed and takes shape in both works is, at least at first sight, very different.

In the second Critique, religion thus defined is associated with the doctrine of the highest good and the affirmation of the immortality of the soul and the existence of God as postulates of pure practical reason. The doctrine of religion is part of morals, and was once described by Kant as a “doctrina moralis indirecta” (VAMS, AA 23: 396). Thus, the “doctrine of Christianity”, “not regarded as a religious doctrine”, according to Kant’s express claim, “gives on this point a concept of the highest good (of the kingdom of God) which alone satisfies the strictest demand of practical reason” (KpV, AA 05: 127–128). “The Christian doctrine of morals” indeed justifies the rational creature “in hoping for his endless duration”, and promotes the realisation of a world “in which nature and morals come into a harmony, foreign to each of them of itself, through a holy author who makes the derived highest good possible” (KpV, AA 05: 128).

In the book published five years later, by contrast, moral religion takes the form of a sui generis interpretation of Christianity precisely as a religious doctrine. Its essential contents include, indeed, the religious doctrine of the peccatum originarium or radical evil in human nature. The book also contains teachings concerning the need for a personified idea of the moral good in the prototype of the Son of God. It incorporates considerations concerning the final destiny of all things and the need for the founding of the Church as a kingdom of God on earth. Finally, there is in the book no lack of meditations on the question of the justification of a guilty human being and the problem of the grace and the means of grace.

Why this difference? Why in the Critique of Practical Reason does moral religion coincide with Christianity as an (indirect) moral doctrine, without needing to consider the properly religious teachings of Christianity, whereas in the Religion Within the Boundaries of Mere Reason moral religion is identified with a certain interpretation of Christianity as a moral doctrine, but also and fundamentally as a religious doctrine? Why is moral religion not reduced to the theoretical requirements emanating from the concept of the highest good, i.e. to the doctrine of the postulates of pure practical reason, but needs to be extended by means of a moral interpretation of certain basic dogmas of Christianity? In what relationship are the conceptions of moral religion set out in the 1788 book and in the 1793 book? What different role, then, does Christianity play in Kant’s elaboration of moral religion in the second Critique and in the book on religion, and what is the relationship between these two roles?

It should be noted that the problem to which these questions refer, although they place Christianity at their centre, is not that of the role of historical or ecclesiastical faith—Christian faith in this case—in the promotion of moral religion.² The above-mentioned questions refer, rather, to a prior and more fundamental problem, namely that of the diversity of the content of the rational faith proper to moral religion. The first problem considers human beings “as citizens within a divine state on earth”. It is a question, therefore, of examining “How does God will to be honored in a church” (RGV, AA 06: 105). The second, in contrast, regards human beings as moral beings. It is, then, a question of establishing “the matter of the veneration of God”—of the moral veneration of God (RGV, AA 06: 105). As ecclesiastical faith, Christianity is an organon or vehicle of moral religion (see SF, AA 07: 37). Hence, the Christian faith can be considered as one more among others, such as, in Kant’s enumeration, the Jewish, the Mohammedan, the Catholic or the Lutheran faiths (see RGV, AA 06: 108). As pure religious faith (based on mere reason), instead, Christianity is the canon, or rule or guide, of moral religion (see SF, AA 07: 37). This is why Christianity is ultimately the only revealed religion that Kant subjects to the so-called “second experiment” to which he refers in the preface to the second edition of his book on religion (see RGV, AA 06: 12).

The distinction between these two problems—that of the role of historical faith in the promotion of moral faith and that of the diversity of the content of rational faith—is crucial to a proper understanding of the relationship between the contents of moral religion set out in the Critique of Practical Reason and those developed in the Religion Within the Boundaries of Mere Reason. It allows us to rule out in advance an unfortunate reductionist portrayal of the book on religion. In the 1793 book, Kant does not simply “translate”, as has sometimes been said, the ecclesiastical faith, the vehicle of moral religion, into the language of rational faith, the criterion of pure moral religion.³In presenting Kant’s project in this way, one might mistakenly think that the teachings of the book on religion do not add anything new to what Kant set out in his ethical writings: we would be dealing with two different versions of the same content, either by translating the language of Christian dogmas into the principles of pure practical reason, or by proceeding the other way round.⁴ Far from it, it is more appropriate to say that, in the book on religion, Kant expands and supplements, with new topics taken from the Christian revelation, the content of the pure rational faith presented in the second Critique. Kant, however, carries out this extension and supplement by trying to harmonise the new data offered by Christianity with the results of the second Critique. Thus he passes them through the sieve of pure practical reason and also relies on new philosophical arguments.⁵

It is equally important to note at the outset that the problem of the diversity of the content of moral religion also does not exactly coincide with the scholarly question of the nature and location in Kant’s writings of the two so-called “experiments” for the construction of moral religion. As is well known, in the preface to the second edition of his book on religion, Kant explains the title of his book by means of the image of two concentric circles, the outer circle of historical faith and the inner circle of rational religion. Regarding the latter, he writes that “the philosopher, as purely a teacher of reason (from mere principles a priori), must keep within the inner circle and, thereby, also abstract from all experience”. With regard to the former, he proposes a “second experiment”, namely, “to start from some alleged revelation”, “to hold fragments of this revelation, as a historical system, up to moral concepts, and see whether it does not lead back to the same pure rational system of religion” (RGV, AA 06: 12).

The methodological question of Kant’s elaboration of rational religion has been the focus of scholarly attention for several years. The main positions under discussion can be schematised as follows.⁶ Some scholars argue that the first experiment only takes place in the second Critique,⁷ while the second experiment is only used in the book on religion as a whole.⁸ Some others claim that Kant carries out both experiments in the Religion Within the Boundaries of Mere Reason. On this point, opinions also diverge. Some hold that the two experiments are carried out successively and jointly in each of the four essays or “pieces” (Stücke) that make up the book.⁹ Others, instead, consider that the second experiment is only carried out by Kant in the fourth and last “piece” of the book, while in the three previous essays the first experiment alone would be used.¹⁰ Finally, a new and bold interpretation has been proposed: In the preface to the second edition of his book on religion Kant does not claim that the elaboration of moral religion is guided by two different experiments.¹¹

The resolution of the debate on the methods—“experiments” or “attempts”—that Kant actually follows in the elaboration of moral religion presupposes a previous task, namely, to justify sufficiently that, however closely related they may be, the subject matter of moral religion presented in the Critique of Practical Reason is not the same as the subject matter dealt with in Religion Within the Boundaries of Mere Reason. Only when the reason for such a difference in the content, the latter of which presupposes and complements the former, has been clarified, will it be possible to adequately justify the different methodical approaches followed in the 1788 book and in the 1793 book for the elaboration of moral religion, as well as the different roles played by Christianity in both works. It will then be seen that the difference between the two methods is based on the origin from which the cognitions of moral religion are obtained. Moral religion is certainly a rational discipline, but in it there are pure a priori cognition and also a priori cognition, but not pure, i.e. a priori cognition admixed with something empirical.¹² It will also be verified that in both methodical procedures the philosophical results obtained are confronted, albeit in different ways, with Christian teachings.

Given the fundamental nature of the problem of the diversity of the content of Kant’s moral religion, there is no shortage of research nowadays that offers plausible explanations of the relationship between the second Critique and the book on religion. There are also recent and valuable accounts of the peculiar character of the Religion Within the Boundaries of Mere Reason and the role played in it by Christianity.¹³ It has been thoroughly explained, for instance, how Kant generates the system of moral religion from the doctrine of the highest good and how Kant’s project is reflected in the internal structure of his book on religion.¹⁴ It has also been convincingly shown that, in that book, Kant turns to Scripture in an attempt to satisfy the “weakness of ours” and to complete the responses to capital philosophical problems that bare reason cannot provide.¹⁵ The undeniable historical fact has been recognised that Kant’s late philosophy of history constitutes the background for the introduction of the concept of radical evil, and that this concept leads Kant to deepen the moral conception of religion, while allowing him to enter into a detailed discussion with the historical religions, especially Christianity.¹⁶ Nor has it failed to be pointed out that Kant’s appreciation of Christianity is an essential part of his project of transcendental philosophy. Certainly, as Kant once expressly recognised, the Gospel is “an everlasting guide to true wisdom,” with which speculative reason agrees and from which it receives “new light on the whole field surveyed by that reason, illuminating what still remains opaque to it” (Letter to Jung-Stilling, after March 1, 1789, Br, AA 11:10).¹⁷ And it has been rightly said, finally—so as not to make this list of examples endless—that the doctrine contained in Kant’s book on religion “moves into the vicinity of a moral anthropology”.¹⁸

In this essay, I intend to contribute to the resolution of the problem of the diversity of the content of moral faith by examining the reasons justifying a thesis of Kant’s that does not seem to have been sufficiently attended to by scholars. It is the thesis that moral religion consists of two parts, one pure and one applied. As is well known, within some philosophical disciplines, Kant distinguishes between a pure part and an applied part. The same is true for moral religion, although Kant merely notes this distinction, without expressly going into detail on the need for this bipartite division. The distinction provides, however, a direct, explicit, and maybe sufficient answer both to the difference and to the mutual and essential connection between moral religion as a doctrine of the postulates of pure practical reason and as a moral interpretation of the dogmas of Christianity. Moreover, the distinction also sheds light on the role played by Christianity in the construction of moral religion.

In what follows, in order to adequately justify the response referred to, I will carry out three main tasks. I will first compare the divisions of logic and ethics with the division of moral religion into pure and applied. I will then set out separately the essential core and the respective method of elaboration of pure and applied moral religion, only insofar as it serves to show the necessity of dividing moral religion in this way and to recognise the role played by Christianity in shaping the two parts of moral religion. Finally, I will very briefly consider two problems concerning the question of hope raised by the results of the Critique of the Power of Judgement, the answers to which confirm the need for a bipartite division of moral religion.

The bipartite division of logic and ethics… and of moral religion

As is well known, in the case of both logic and ethics, Kant distinguishes respectively pure logic and applied logic, and pure ethics (or “metaphysics of morals”) and applied ethics (or “practical anthropology” or “moral anthropology”). In both cases it is a matter of distinguishing a more universal and non-empirical cognition from a less universal and empirically mixed cognition. The distinction between both kinds of cognitions is obtained through the mediation of a third discipline, psychology, in the case of logic, and anthropology, in the case of ethics.

Thus, pure logic is a pure a priori cognition of a theoretical (and normative) character,¹⁹ which deals with the necessary laws of thought. Applied to psychology, which is a theoretical and empirical science, it gives rise to an a priori, but not pure, theoretical (and normative) cognition, i.e. applied logic. In pure logic, Kant writes, “we abstract from all empirical conditions under which our understanding acts.” Applied logic, instead, Kant claims, “is directed to the rules of the use of the understanding under the subjective empirical conditions that psychology teaches us” (KrV, A 53/B 77).

Similarly, the metaphysics of morals is a pure a priori cognition of a practical nature, which deals with the laws of freedom. When this pure cognition is applied to anthropology, which is a theoretical and empirical science, it produces an a priori, but not pure, cognition of a practical nature, i.e. practical or moral anthropology. Certainly, the “a priori source” from which the principles of the metaphysics of morals arise always safeguards their “purity”, but these principles are often applied to “the particular nature of human beings, which is cognised only by experience, in order to show in it what can be inferred from universal moral principles”. Moral anthropology, therefore, will deal with “the subjective conditions in human nature that hinder people or help them in fulfilling the laws of a metaphysics of morals” (MS, AA 06: 217).

Kant argues that moral religion too is composed of two heterogeneous parts: a “pure” religion and an “applied” religion. As for religion set forth in the Critique of Practical Reason, i.e. religion as a doctrine of the postulates of pure practical reason, Kant unequivocally claims its pure nature as follows:

Natural religion, as morality (with reference to the freedom of the subject), combined with the concept of that which can actualize its ultimate end (the concept of God as moral originator of the world), and referred to a duration of the human being proportionate to the entirety of this end (immortality), is a pure practical concept of reason. (RGV, AA 06: 157).

As for religion presented in the Religion Within the Boundaries of Mere Reason, i.e. religion as a moral interpretation of Christian dogmas, Kant also expressly points out its character as an applied discipline. In the preface to this book, in introducing the four treatises or “pieces” of which it is composed, Kant states that they seek “to make apparent the relation (Beziehung) of religion to a human nature partly laden with good dispositions and partly with evil ones” (RGV, AA 06: 11).

In The Metaphysics of Morals, published four years after the book on religion, Kant again unequivocally points to the two-part division of moral religion, even calling the two parts “pure” and “applied”:

We can indeed speak of a “Religion within the Boundaries of Mere Reason”, which is not […] derived from reason alone but is also based on the teachings of history and revelation, and considers only the harmony of pure practical reason with these (shows that there is no conflict between them). But in that case […] religion is not pure; it is rather religion applied to a history handed down to us (MS, AA 06: 488).

Obviously, the statements concerning applied moral religion have not gone unnoticed by scholars of Kant’s philosophy of religion.²⁰ However, the consequences of the distinction between the pure and the applied for explaining Kant’s philosophical project on religion do not seem to have been sufficiently emphasised. Before considering these consequences, pointing out the irreducible peculiarities of pure moral religion and applied moral religion, we should note two facts that in a certain way break the analogy of the division of moral religion with the divisions of logic and ethics. These facts, however, also help to highlight the idiosyncrasy of the distinction that Kant introduces within moral religion.

The first fact is that the pure laws of thinking—the subject matter of pure logic, as well as the universal and necessary laws of willing—the subject matter of pure ethics or metaphysics of morals—are valid for all rational beings, including in a certain sense the infinite rational being. Certainly, the distinction between the pure and the applied does not make sense in the case of the infinite rational being. However, an analogue of these pure laws of thinking and willing can be attributed to God’s understanding and will. According to Kant, indeed, in the concept of God we think of a being to whose understanding belongs intellectual intuition (see KrV, B 72) and to whose will belongs the moral government of the world (see RGV, AA 06: 99). This analogy, however, breaks down in the case of the pure moral religion: its principles are only valid for all finite rational beings. Obviously, the infinite rational being we call God cannot be said to have any religion. For the rest, both applied logic and applied ethics, and also applied moral religion, all agree that their cognitions are valid only for the case of a particular finite rational being, the human being. All these sciences indeed contain a priori cognitions, though not pure, but mixed with empirical elements, since they are applied to a cognition—that of human nature—that can only be obtained from experience.

The second fact mentioned refers to the third discipline that allows the passage from the pure to the applied part of a science. In the case of both logic and ethics, we are dealing with philosophical disciplines of an empirical nature in a certain way already constituted: psychology and anthropology, respectively. In the case of moral religion, the mediating discipline is not properly an empirical discipline, but an a priori discipline, though not a pure one. Until the time Kant wrote his book on religion, this discipline had not yet been formally constituted. It consists of the rational elaboration and justification of those truths about the moral nature of human beings with which Christianity, as a historical system, has enriched philosophy. To these truths can be applied what Kant says about the concepts with which Christianity “has enriched morality”, namely, that they are truths “which, once they exist, are freely approved by reason and assumed as ones that it could have arrived at and which it could and should have introduced by itself” (KU, AA 05: 472 note). Kant builds this peculiar moral anthropology—of which it can be said to be both “Christian”, in the sense that it is strongly influenced by the teachings of Christianity, and also “philosophical”, in the sense that it is grounded in reason alone—at the same time as he elaborates his applied religion, thus forming an inextricable part of it. In this way, Kant fulfils what he announced in the preface to the second edition of his book on religion, namely, “to make apparent the relation of religion to a human nature partly laden with good dispositions and partly with evil ones” (RGV, AA 06: 11).

As is well known, Kant states that pure logic is “a canon of the understanding and reason” (KrV, A 53/B 77), while applied logic is “merely a cathartic of the common understanding” (KrV, A 54/B 78). Would it not then be possible to claim that pure moral religion is properly the canon, “rule” or “criterion”, of natural religion and that applied moral religion is the catharticon, “purgative” or “purifier”, of natural religion? Let us find out whether this parallelism holds, and if so, in what sense, by showing the need to distinguish the bipartition of moral religion into pure and applied and by examining the role Christianity plays in both parts of moral religion.

Pure moral religion

Kant’s thesis is well known. Morality does not need the idea of God for the human being to “recognize his duty” nor, in order for him to observe it, “of an incentive other than the law itself” (RGV, AA 06: 3). However, morality “inevitably leads to religion”, thus extending “to the idea of a mighty moral lawgiver outside the human being, in whose will the final end (of the creation of the world) is what can and at the same ought to be the final human end” (RGV, AA 06: 6). Why does morality inevitably lead to religion? Why should we recognise our moral duties as divine commands?

In the Critique of Practical Reason Kant offers a first answer to this question. In this work, the philosopher teaches that the actual realisation of the final end that practical reason commands is not, as a matter of principle, in the power of any finite rational being. Its achievement, however, is a duty for this being. Neither the supreme condition of the highest good, virtue, or rather, holiness, nor the subordinate condition, the attainment of happiness in accordance with morality, are within the reach of any finite rational being, nor, therefore, of any human being. On the one hand, “no rational being of the sensible world”, Kant writes, “is capable at any moment of his existence” of holiness, i.e. of a “[c]omplete conformity of the will with the moral law” (KpV, AA 05: 122). “The holiness of will is”—Kant says on another occasion—“a practical idea, which must necessarily serve as a model to which all finite rational beings can only approximate without end” (KpV, AA 05: 32). Holiness “is an idea that can be contained only in an endless progress and its totality, and hence is never fully attained by a creature” (KpV, AA 05: 123 note). On the other hand, neither can any limited rational being achieve the goal that, in the whole of his existence, everything in the world “goes according to his wish and will” just by being virtuous (KpV, AA 05: 124). Shall we then consider as an absurdum practicum the command of promoting the highest good?

The fact—the fact of reason—of our consciousness of the moral law (see KpV, AA 05: 31) leads Kant to admit truths that were closed to speculative reason, not in order to expand knowledge, but only to gain the intimate certainty that it is possible to achieve the perfect fulfilment of the final end of moral life. Such truths are the immortality of the soul and the existence of God. By “immortality of the soul” is meant the existence, continued in a progress to infinity, of a rational being in which his “weal or woe is to be allotted to him in proportion to his moral worth” (VNAEF, AA 08: 418. See KpV, AA 05: 122). By “existence of God” is meant the claim that there is a highest moral being who, “by understanding and will”, is the author of nature (KpV, AA 05: 125). Both truths are, according to Kant, conditions of possibility for the realisation of the highest good, i.e. our final moral end. Both are, in Kant’s technical term, “postulates of pure practical reason”, i.e. theoretical propositions, albeit not demonstrable as such, which are inseparably attached to the moral law (see KpV, AA 05: 122).

These two articles of faith, of rational or moral faith, i.e. these credibilia of pure practical reason to which morality leads, form the fundamental content of pure moral religion. They are the pure a priori cognitions constituting the pure part of moral religion. It is on these articles of moral faith that the hope which pure moral religion encourages in us is founded. Kant confirms this unequivocally: “[T]he moral law leads through the concept of the highest good, as the object and final end of pure practical reason, to religion, that is, to the recognition of all duties as divine commands”. The reason for the need of religion thus understood is, therefore, that “only from a will that is morally perfect (holy and beneficent) and at the same time all-powerful […] can we hope to attain the highest good, which the moral law makes it our duty to take as the object of our endeavors” (KpV, AA 05: 129).

There is no denying that Kant was inspired by Christian doctrine to elaborate his own moral doctrine and the pure moral religion to which it leads. As Kant recognised on several occasions, “if the gospels had not previously instructed us in the universal moral laws in their total purity, our reason would not yet have discovered them so completely”. This does not prevent, however, that “once we are in possession of them, we can convince anyone of their correctness and validity using reason alone” (Letter to F. H. Jacobi, August 30, 1789, Br, AA 11: 76; see KU, AA 05: 472 note). In this sense, it could be said that both Kant’s moral doctrine and pure moral religion constitute a strictly rational justification of certain truths that Christianity has taught for the first time.

It is important to note, however, that Kant, in the Critique of Practical Reason, when constructing his moral doctrine and the pure moral religion to which it leads, adheres strictly to that first method or “experiment” to which he would refer (without enumerating it) years later in his book on religion. The use of this method inevitably demands proceeding according to pure a priori principles, abstracting from all experience. But this method does not exclude the subsequent comparison of the results obtained with the findings of other systems of thought. Thus, as Kant states, “the philosopher, as purely a teacher of reason” must seek—as is the case here—the principles of morality and the foundations of religion “from mere principles a priori”, abstracting “from all experience” (RGV, AA 06: 12). Then, later in his book Kant considers Christian morality “on the philosophical side” (KpV, AA 05: 127 note) and finds in it a venerable historical illustration, so to speak, of the harmony between the truths discovered by bare reason and those offered by Christian revelation. In any case, however, pure moral religion is the only canon by which to judge the truths offered by Christianity. Thus, Kant states that the commandment of love of God and neighbour, that “law of all laws” that Jesus put at the centre of his teaching, “like all the moral precepts of the Gospel, presents the moral disposition in its complete perfection” (KpV, AA 05: 83). Moreover, as noted above, the Christian concept of the “kingdom of God”, i.e. of the highest good, is the only one that satisfies the strictest demand of practical reason by justifying the creature in hoping for his “endless duration” and by affirming the harmony of nature and morals through the existence of “a holy author” (KpV, AA 05: 127–128).

In this sense, therefore, Christianity plays a peculiar role in the elaboration of pure moral religion. Christianity, by harmonising fully and wonderfully with the doctrines of pure practical reason, illustrates and endorses, without claiming to offer a philosophical justification, the truth of these doctrines. The role played by Christianity in this case—the illustration and endorsement of the doctrines of pure practical reason—is apparently modest. However, any other historical religion is, according to Kant, very far from being able to play this role (see RGV, AA 06: 51–52, 167). Christianity is thus recommended as the revealed religion from which the greatest fruits for the philosophical doctrine of religion are to be expected—fruits that will then have to be justified by means of bare reason. But having examined the pure use of practical reason, Kant can already recognise that the Christian principle of morals is not heteronomy, but autonomy of pure practical reason, “since it does not make cognition of God and his will the basis of these laws but only of the attainment of the highest good subject to the condition of observing these laws” (KpV, AA 05: 129). Moreover, according to Kant, Christianity can rightly be said to offer a moral concept of God that is fully consonant with the object of pure practical reason. Christianity conceives of God, in fact, as a being of the highest perfection, omniscient “in order to cognize my conduct even to my inmost disposition in all possible cases and throughout the future”, omnipotent “in order to bestow results appropriate” to my moral conduct, “and so too omnipresent, eternal, and so forth” (KpV, AA 05: 140).

Nevertheless, pure moral religion, even thus illustrated by Christian doctrine considered “on the philosophical side”, does not yet completely answer the question posed: Why does morality inevitably lead to religion? The insufficiency of the first response given in the second Critique lies in the methodological limitation of the examination of the pure use of practical reason. A critique of practical reason as such, Kant writes, “has only to give a complete account of the principles of its possibility, of its extent, and of its limits, without special reference to human nature” (KpV, AA 05: 8, emphasis added). Therefore, the aforementioned credibilia of pure practical reason are valid, as a matter of principle, for all finite rational beings, and not only and exclusively for human beings.²¹ A new question then arises: Is rational faith in the immortality of the soul and in the existence of God all that human beings as such can and should hope for when considering their moral duties as divine commands? In other words: Regarding the hope for the realisation of the ultimate moral end, is there no difference between any finite rational being and the particular finite rational being that is the human being?

Applied moral religion

To the concise doctrine on religion presented in the Critique of Practical Reason, Kant adds the lengthy teachings contained in the 1793 book. The reason for this addition is Kant’s conviction that moral faith in the immortality of the soul and in the existence of God is not all that human beings as such can and should hope for when considering their moral duties as divine commands, for such faith is not enough to keep them from losing heart in the pursuit of the final end of their moral actions. The particular moral nature of the human being requires new credibilia of practical reason on which to ground hope in achieving the final end of moral life.

Certainly, the realisation of the ultimate end of moral action is not, as a matter of fact, in the power of any of those particular finite rational beings that we human beings are. In this case, it is not about an impossibility grounded on our ontological finitude, shared with every finite rational being—finitude that does not depend on our freedom. It is not that the brevity of our sensible life and the limitations of our faculties prevent us from attaining the ultimate end of moral life. Rather, in this case, the impossibility is due to the moral nature of the being who has to fulfil the moral duty—a nature for which we are entirely responsible and which, therefore, need not be shared by any other possible finite rational being. It is, indeed, our particular moral condition, born of the first use of our power of choice in adopting the maxims of our conduct, which places insurmountable obstacles in the way of the realisation of our final moral end. Human beings are indeed rational beings in whose particular nature morally good predispositions (Anlagen) are mixed with a propensity (Hang) to evil. How can a rational being who is prone to evil and even burdened with moral guilt live his moral duties as divine commands?

Kant’s answer to this question constitutes the essential content of applied moral religion, i.e. the subject matter of the Religion Within the Boundaries of Mere Reason. In the search for this response, Kant abandons the method used to elaborate pure moral religion, i.e. the so-called “first experiment”, which required abstracting from all experience and proceeding only according to pure a priori principles. Kant then proposes to follow a new method, which is undoubtedly recommended to him by the philosophical wealth he has discovered in Christianity. This is the method which, in the preface to the second edition of his book on religion, he calls the “second experiment” or “second attempt”. It consists essentially of examining the teachings of Christianity on the moral nature of human being and his need for salvation in order to verify not only the “compatibility” but also the “unity” of the Christian dogmas (see RGV, AA 06: 13) with the doctrines of pure practical reason. In Kant’s own words, it is a matter of “hold[ing] fragments of this revelation, as a historical system, up to moral concepts and see[ing] whether it does not lead back to the same pure rational system of religion” (RGV, AA 06: 12). Consequently, in order to show the unity or compatibility of certain fundamental Christian teachings with the doctrines of pure practical reason, Kant proceeds both by directly stating what reason alone discovers when applied to the study of the moral nature of the human being (without even hinting at its otherwise obvious inspiration in a Christian teaching) and by explicitly considering some Christian teachings from the point of view of pure morality.

It can therefore be said that the first two treatises or “pieces” of Kant’s book on religion essentially set out the fundamental tenets of what can be called “Christian moral anthropology of fallen nature within the limits of mere reason”. It is, in fact, a moral anthropology that deals with the human being in statu naturae lapsae (in a state of fallen nature), to use a common expression in Christian theology, i.e. in a state of nature “partly laden with good dispositions and partly with evil ones” (RGV, AA 06: 11), in Kant’s own words. As previously stated, Kant’s purpose in his book on religion is to make apparent the relation—“application”, we might say—of pure religion to human nature thus understood.

The first two parts of Kant’s book on religion constitute also a moral anthropology within the boundaries of mere reason because they justify and substantiate their claims by reason alone, without the support of positive revelation. They aspire indeed to elaborate a universal wisdom about the moral condition of the human being, recognisable as true by all, irrespective of the particular religious tradition in which one believes, if that is the case. Kant actually shares with Christianity the claim, which he tries to justify rationally, that all human beings are originally good, but that, nevertheless, each one of them has begun his moral life, which strictly speaking does not take place in time, by carrying out a choice, of which no one has any memory, in favour of evil, which has radically perverted him.²² Thus, because of this peccatum originarium (RGV, AA 06: 31), there is “the radical evil in human nature”, as we read in the title of the first treatise of the book on religion. The moral indigence of the human being is clearly manifested—a matter that Kant also tries to explain rationally—in the permanent “struggle of the good with the evil principle for dominion over the human being”, as we also read in the title of the second treatise of the book.

However, this moral anthropology is also, finally, a Christian moral anthropology not only in the sense that its inspiration in biblical teachings cannot be concealed, but also, above all, in the sense that it tries to show that there are fragments of Christian revelation that, held up to moral concepts, are compatible with the doctrines of pure practical reason. Thus, as Kant also attempts to do in the first treatise of his book, the biblical story of the Fall of our First Parents—the dogma of original sin—can be interpreted philosophically as the assertion that “[e]very evil action must be so considered, whenever we seek its rational origin, as if the human being had fallen into it directly from the state of innocence”, for his action is, in all cases, free and not determined through any natural cause and, therefore, “can and must always be judged as an original exercise of his power of choice” (RGV, AA 06: 41).

Similarly, Kant attempts, in the second treatise of the book, to interpret philosophically the figure of Christ, the “Son of God”—the teacher of the Gospel, as he calls him—as “the personified idea of the good principle” (RGV, AA 06: 60), as “the prototype of moral disposition in its entire purity” (RGV, AA 06: 61). However, neither his divinity, nor his incarnation, nor his vicarious sacrifice can be held up to moral concepts. To affirm the divinity of Christ, Kant writes, “would rather, from all that we can see, stand in the way of the practical adoption of the idea of such a being for our imitation” (RGV, AA 06: 64). Nor can his incarnation be rationally recognised, for “the good principle did not descend among humans from heaven at one particular time but from the very beginning of the human race, in some invisible way” (RGV, AA 06: 82). Nor, finally, can his death on the cross be understood as a vicarious atonement, however inexplicable it may be that a sinner who has contracted an “infinity of guilt” (RGV, AA 06: 72) can (“because it is a duty”) bring about a “change of the heart” (RGV, AA 06: 56–57); just as it is also inexplicable that such a sinner can be imputed to merit what should be admitted as the fruit of grace (see RGV, AA 06: 75). In this second treatise, Kant also interprets the gospels as narrating the battle between good and evil that takes place in the heart of every human being “in the form of a story in which two principles, opposed to each other like heaven to hell and represented as two persons outside the human being […] test their respective power in him” (RGV, AA 06: 78). These “two persons” are obviously Jesus, “the teacher of the Gospel” (RGV, AA 06: 128), and Satan, the “tempting spirit” (RGV, AA 06: 44).

In the same way, the last two treatises or “pieces” of the book on religion contain what might be called the “Christian anthropology of redeemed nature or soteriology within the limits of mere reason”.²³ It is a soteriology because it deals with the human being in statu naturae redemptae (in a state of redeemed nature), to use again a common expression in Christian theology or, more precisely in this case, with what Kant would describe as the nature of “every morally well-disposed human being” who “hope[s] for a victory of the good principle over the evil one” (RGV, AA 06: 93–94). As recalled, Kant also describes the character of his book on religion as a “religion applied to a history handed down to us” (MS, AA 06: 488), applied, therefore, to the so-called “salvation history” of mankind, which has contracted an innate and infinite guilt.

These last two treatises of Kant’s book are equally a soteriology within the boundaries of mere reason because they are built by means of evidence and rational argumentation alone. Thus, in the third treatise of the book on religion—entitled “The victory of the good principle over the evil principle, and the founding of a kingdom of God on earth”—Kant defends the need—which actually constitutes a duty of a special kind—for every human being who wants to escape the dominion of the evil principle and to avoid the “incessant danger of relapsing into it”, to associate with other human beings, “merely under the laws of virtue” (RGV, AA 06: 94), in an “ethical community” or “kingdom of virtue”. Kant not only claims that the idea of this ethical community “has an entirely well-grounded, objective reality in human reason” (RGV, AA 06: 95), but even that reason itself teaches that the foundation of such an ethical community is “a work whose execution cannot be hoped for from human beings but only from God himself” and therefore “cannot be realized (by human organisation) except in the form of a church” (RGV, AA 06: 100). Likewise, in the fourth essay of his book, Kant is concerned to distinguish, as his title announces, the “service and counterfeit under the dominion of the good principle”. The distinction is based on a moral principle that Kant considers self-evident. He states it as follows: “Apart from a good life-conduct, anything which the human being supposes that he can do to become well-pleasing to God is mere religious delusion and counterfeit service of God” (RGV, AA 06: 170–171). Kant even claims that reason confirms that whoever does everything in his power to fulfil his moral duties “can legitimately hope that what lies outside his power will be supplemented by the supreme wisdom in some way or other” (RGV, AA 06: 171).

Finally, this philosophical soteriology is also Christian in the aforementioned double sense: it is primarily inspired by Christianity, and above all it tries to show that certain Christian salvific teachings, held up to moral concepts, harmonise fully with the doctrines of pure practical reason. Thus, in the third “piece” of his book, Kant argues that only the Christian church bears within it “the germ and the principles of the objective unity of the true and universal religious faith” (RGV, AA 06: 125) and offers a history of the Christian church in which—in his view—its discouraging past and its hopeful future are explained in terms of the opposition between historical faith and true religious faith. Similarly, in the fourth essay of the book, Kant declares that the “teacher of the Gospel” is the founder, not of the moral religion, but indeed of “the first true church” (RGV, AA 06: 159) and claims that the New Testament presents “complete religion, which can be proposed to all human beings comprehensibly and convincingly through their own reason” (RGV, AA 06: 162).

The contents of this “complete religion”, in which the discoveries of bare reason and the fundamental teachings of Christianity coincide or are in agreement, thus constitute the new credibilia of pure practical reason.²⁴ Morality considered with special reference to human nature leads to a new way of recognising our moral duties as divine commandments, since human beings cannot count on the presupposition of a prior innocence, but rather on that of an original depravity of their power of choice. Thus Kant states not only that the ultimate end of our moral action coincides with the final end that God Himself has set in creating the world and the human beings in it (see KpV, AA 05: 130, RGV, AA 06: 6), but also that this coincidence is the only thing that can give rise in us to the hope of achieving our ultimate moral end, despite our moral neediness and our constitutive incapacity for good. Nearly 20 years before the publication of his book on religion, Kant recognised indeed that “the essential and most excellent part (das wesentliche und vortreflichste) of the teachings of Christ is this: that righteousness is the sum of all religion”. Consequently, Kant continues, “we ought to seek it with all our might, having faith (that is, an unconditional trust) that God will then supplement our efforts and supply the good that is not in our power” (Draft of a letter to Johann Caspar Lavater, after April 28, 1775, Br, AA 10: 180).

Thus, the articles of faith that make up pure moral religion (the immortality of the soul and the existence of God), valid for every finite rational being, are now enriched by these new credibilia, which are the a priori, but not pure cognitions constituting the applied part of moral religion. They are indeed articles of faith proper to the practical reason of the peculiar finite rational being that is the human being. They add to the pure part of moral religion, a true canon of natural religion, as a catharticon of moral religion, by teaching human beings the need for inner transformation, liberation from guilt, and moral purification.

Pure and applied moral religion and the question of hope

The division of moral religion into two parts, the pure and the applied, brings out with particular clarity one aspect of the capital problem which, within transcendental idealism, the linking of the theoretical and practical parts of the system of philosophy poses. The exposition and assessment of Kant’s solution to this problem, its many complexities, and its manifold repercussions are far beyond the scope of this essay. A few brief indications will suffice, however, to better understand the meaning of Kant’s conception of moral religion and to confirm the necessity of its bipartite division.

As is well known, Kant claims that religion tries to answer the question of hope: “If I do what I should, what may I then hope?” (KrV, A 805/B 833; see Log, AA 09: 25; Letter to C. F. Stäudlin, May 4, 1793, Br, AA 11: 414). In this question, the practical interest and the theoretical interest of reason come together, since, as Kant writes, “all hope concerns happiness, and with respect to the practical and the moral law it is the very same as what knowledge and the natural law is with regard to theoretical cognition of things” (KrV, A 805/B 833). The practical infers indeed that something is “because something ought to happen”, while the theoretical concludes that something is “because something does happen”. Hope is thus grounded on the assumption that, what ought to happen—i.e. what ought to be—will happen—i.e. will be.

Now, between what ought to be and what is, between the practical and the theoretical, between freedom and nature, there is, in Kant’s famous expression, not only a distinction but an “incalculable gulf”. A basic tenet of transcendental idealism is indeed that “the concept of freedom in its object makes a thing representable in itself but not in intuition”, while “the concept of nature certainly makes its objects representable in intuition, but not as things in themselves, rather as mere appearances” (KU, AA 05: 175). Therefore, between the objects of the concept of freedom and those of the concept of nature there is an insurmountable distance: the distance which separates the supersensible from the sensible, the noumena from the phenomena.

But transcendental idealism also affirms with equal force that the transition from the practical to the theoretical, from freedom to nature, must be possible, simply because “freedom should make the end that is imposed by its laws real in the sensible world”. Consequently, nature must “also be able to be conceived in such a way that the lawfulness of its form is at least in agreement with the possibility of the ends that are to be realized in it in accordance with the laws of freedom” (see KU, AA 05: 176).

As is well known, Kant argues that the necessary transition between the concept of nature and that of freedom can be provided neither by understanding nor by reason. Only the power of judgment, the reflecting power of judgment, can be the link between the theoretical and the practical, between nature and freedom. This is because of the transcendental principle of the power of judgment, i.e. the principle of the formal purposiveness of nature. This principle makes it possible to think, although not to know theoretically, the laws of nature as a teleological system that makes possible the realisation of the highest good, the final end of all finite rational beings, i.e. the achievement of happiness in accordance with morality (see KU, AA 05: 196).²⁵

What are the main consequences of these considerations, which Kant explains, justifies, and develops particularly in the second part of his Critique of the Power of Judgment, for the answer to the question of hope, i.e. the question of religion?

As we know, the Critique of Practical Reason provided a ground for hope and thus laid the foundations of pure moral religion. It provided indeed an answer to a capital problem posed by the possibility of achieving the final end of the moral life of every finite rational being. The problem is: May a rational being hope—because it is thinkable, though not cognisable—for a unity of the moral good (bonum supremum), governed by the laws of freedom, and the natural good (morally deserved happiness), governed by the laws of nature, goods which, together, constitute the complete good (bonum consummatum) commanded by the moral law? The admission, on moral grounds and for a practical purpose only, of the existence of God is presented in this work as a postulate of pure practical reason and thus as the basis for the hope that all finite rational beings will regard their moral duties as divine commands.

But the results of the Critique of the Power of Judgment give new reasons for hope because they make it possible to find an answer to two new capital problems. The first one concerns, like the previous problem, the hope that pure moral religion tries to account for. It can be formulated in two related and correlative questions. On the one hand, may a rational being hope his moral acts occur in nature, given that such acts are performed according to the laws of freedom and that nature only obeys the laws of natural causality and thus excludes the causality of freedom? On the other hand, may a rational being hope morally deserved happiness will be an end of nature, nature being alien to morality? According to Kant’s research, the principle of reflective judgement allows us to admit, not as an object of cognition, but as an object of moral faith, that “the whole of creation would be a mere desert, existing in vain and without a final end”, if there were no “rational beings in general” (KU, AA 05: 442). These beings, insofar as they are moral beings, are indeed to be considered as the final end of a supreme creator and moral legislator of the world (see KU, AA 05: 447–450). Pure moral religion thus finds in what Kant calls “ethicotheology” new grounds for the fulfilment of the hope of every rational being. It is understandable, therefore, that Kant characterises religion—pure moral religion, in particular—with formulas such as these: “religion […] is morality applied to God”, or “morality and theology in combination constitute religion” (V-Mo/Collins AA 27: 305).

The second problem mentioned refers to the peculiar hope that applied moral religion tries to underpin. This problem is not posed by Kant in the Critique of the Power of Judgment. But his answer is based on the results obtained in the third Critique. It can be formulated as follows: May human beings hope that, having used their freedom in favour of evil, they can return to the path of moral good and obtain the highest good to which they have been called?²⁶ The admission that human beings, as rational moral beings, are the final end of the divine creation, together with the consideration of the doctrines of Christianity “held up to moral concepts” and in harmony with pure practical reason, allow Kant to propose the grounds for the hope that all human beings, despite their fall into evil, can continue to consider their moral duties as fully realisable divine commands. It is also understandable, therefore, that Kant describes the true end of religion—of applied moral religion, in particular—as “the moral improvement of human beings” (RGV, AA 06: 112).

Consideration of the two problems concerning the question of hope which, in one way or another, arise in the light of the results of the Critique of the Power of Judgment, show once again the necessity for the bipartite division of moral religion. The answer to the first problem provides the pure a priori foundations of rational hope. The answer to the second problem presents the a priori, but not pure, foundations of rational hope, more precisely, of properly human hope. Thus, the pure moral religion expounded in the Critique of Practical Reason finds a deeper foundation, fulfilment and development in the Critique of the Power of Judgment. Applied moral religion, i.e. Religion Within the Boundaries of Mere Reason, builds on the achievements of the third Critique, while supplementing them with essential considerations on the moral nature of the human being and his need for salvation.²⁷

Concluding remarks

In the preceding pages, I have tried to show that Kant’s division of moral religion into two parts, the pure and the applied, arises from the discovery of a double impossibility, ontological and moral, which prevents human beings from achieving the actual realisation of the final end that practical reason commands. Because of its ontological limitation, no finite rational being, and therefore no human being, has the power to fulfil the conditions for the realisation of the highest good. Because of his moral nature, the human being, “partly laden with good dispositions and partly with evil ones” (RGV, AA 06: 11), cannot free himself from the infinite guilt he has incurred and return to the path of moral goodness. Hence, given this double impossibility, morality inevitably leads to religion, i.e. to the recognition of moral duties as divine commands, thus encouraging the hope that God will carry out what is impossible for human beings, even though it is a duty for them. Pure moral religion concerns the overcoming of the ontological impossibility, while applied moral religion concerns the overcoming of the impossibility born of the human being’s first use of freedom. Pure moral religion is constituted from the pure use of practical reason. It is thus the canon of moral religion, by which the moral doctrine of Christianity and the consequences to which it leads are subsequently proved to coincide with moral religion. Applied moral religion arises from the consideration of the anthropological and soteriological doctrines offered by Christianity as a historical religion, but only of those capable of being held up to moral concepts, i.e. capable of conforming to the canon of moral religion. It is thus constituted as a catharticon or “purgative” of the will of the human being who tries to recognise his moral duties as divine commands.

Broadly speaking, Kant deals with pure moral religion in the Critique of Practical Reason and with applied moral religion in Religion Within the Boundaries of Mere Reason.²⁸ However, the division of the two parts of moral religion is an ideal division, which, as in analogous cases, Kant did not separate drastically in the books he actually published. Thus, for example, although Kant distinguishes the metaphysics of morals, as pure a priori knowledge, from moral anthropology, as pure knowledge mixed with something empirical, it is clear that The Metaphysics of Morals as actually published contains much research on moral anthropology. Something similar can be said of Kant’s book on religion. In addition to expounding strictly religious doctrines, it contains considerations on the conditions of possibility of the highest good, a matter proper to the examination of the pure use of practical reason, as well as many investigations of moral anthropology. Kant’s motives for proceeding this way in these books are easy to understand. On the one hand, the purity of the moral law, valid not only for human beings but for all rational beings, should be clearly stated. On the other hand, however, it is necessary to take into account the only rational being that we know by experience.

As has been seen, Christianity plays a dual role in the elaboration of moral religion. In pure moral religion, Christianity stands only as a final term of comparison, illustrating the moral and religious truths previously discovered by pure practical reason by actually harmonising with them. In the case of pure moral religion, therefore, Christianity illustrates and endorses, without claiming to offer a philosophical justification, the results obtained by reason. In applied moral religion, instead, Christianity is presented as a starting point, which inspires pure practical reason in the discovery of new anthropological and soteriological truths that fully harmonise with those already discovered. Thus, in the case of applied moral religion, reason confirms and rationally justifies the teachings of Christianity. In both cases, pure practical reason and certain fragments of Christianity are shown to be in complete harmony.

In this respect, Kant is right when he defends himself against the accusations that the official Prussian censorship levelled against his book on religion. Far from having “distort[ed] and disparage[d]” (SF, AA 07: 7) the cardinal teachings of Christianity, Kant states that Religion Within the Boundaries of Mere Reason contains “no appraisal of Christianity”, but appraises “only natural religion” (SF, AA 07: 8). Certainly, by supplementing pure moral religion with applied moral religion, Kant seeks to find out to what extent certain dogmas of Christianity are in harmony with the discoveries of bare reason and can legitimately form part of natural religion or moral religion. He does not, therefore, claim to pronounce on the truth of Christian revelation as such, i.e. on the truth of certain religious doctrines that are “outside the boundaries of mere reason”.²⁹ Thus, Kant can write that his book exposes the “best and most lasting eulogy” of Christianity, precisely because in it, “its harmony […] with the purest moral belief of religion” is demonstrated (SF, AA 07: 9).

List of abbreviations, editions, and translations used to cite Kant’s works

AA	Kant’s gesammelte Schriften. Akadamie Ausgabe. Edited by the Royal Prussian, later German, then Berlin-Brandenburg Academy of Sciences (Berlin: Georg Reimer [later Walter de Gruyter], 1900)
	Citations with indications of volume number, followed by a colon and page number
	Translations of Kant’s works are taken from The Cambridge Edition of the Works of Immanuel Kant. Ed. by Paul Guyer and Allen W. Wood. Cambridge: Cambridge University Press, 1992
Br	Briefe
	English version: Immanuel Kant, Correspondence. Translated and edited by Arnold Zweig. Cambridge: Cambridge University Press, 1999
KpV	Kritik der praktischen Vernunft
	English version: Critique of Practical Reason. In Immanuel Kant, Practical Philosophy. Translated and edited by Mary J. Gregor. Cambridge: Cambridge University Press, 1996
KU	Kritik der Urteilskraft
	English version: Critique of the Power of Judgment. Traslated by Paul Guyer and Eric Matthews. Cambridge: Cambridge University Press, 2002
KrV	Kritik der reinen Vernunft
	Citations refer to the pagination in the first (A) and in the second edition (B)
	English version: Critique of Pure Reason. Translated and edited by Paul Guyer and Allen W. Wood. Cambridge: Cambridge University Press, 1998
MS	Die Metaphysik der Sitten
	English version: The Metaphysics of Morals. In Immanuel Kant, Practical Philosophy. Translated and edited by Mary J. Gregor. Cambridge: Cambridge University Press, 1996
RGV	Die Religion innerhalb der Grenzen der bloßen Vernunft
	English version: Religion Within the Boundaries of Mere Reason. In Immanuel Kant, Religion and Rational Theology. Translated by George di Giovanni. Cambridge: Cambridge University Press, 1996
SF	Der Streit der Fakultäten
	English version: The Conflict of the Faculties. In Immanuel Kant, Religion and Rational Theology. Translated by Mary J. Gregor and Robert Anchor. Cambridge: Cambridge University Press, 1996
V-Mo/Collins	Vorlesungen Wintersemester 1784/1785. Moralphilosophie Collins
	English Version: Moral philosophy: Collins’s lecture notes. Translated by Peter Heath. In Immanuel Kant, Lectures on Ethics. Edited by Peter Heath and J. B. Schneewind. Cambridge: Cambridge University Press, 1997
V-Phil-Th/Pölitz	Vorlesungen Wintersemester 1783/1784. Philosophische Religionslehre nach Pölitz
	English version: Lectures on the philosophical doctrine of religion. In Immanuel Kant, Religion and Rational Theology. Translated by Allen W. Wood. Cambridge: Cambridge University Press, 1996
VAMS	Vorarbeit zur Metaphysik der Sitten
VNAEF	Verkündigung des nahen Abschlusses eines Tractats zum ewigen Frieden in der Philosophie
	English version: Proclamation of the imminent conclusion of a treaty of perpetual peace in philosophy. Translated by Peter Heath. In Immanuel Kant, Theoretical Philosophy after 1781. Edited by Henry Allison and Peter Heath. Cambridge: Cambridge University Press, 2002