Kant’s Moral Theism and the Concept of the Highest Good

Abstract

The concept of the highest good plays a vital role in Kant’s moral theism. However, as many scholars suggest, Kant’s own texts about the very concept can be interpreted in different ways, some of which may imply that the practical postulate of God is not necessary for the realization of the highest good. In this paper, I argue, on the contrary, that within the framework of Kant’s philosophy, no matter how we interpretate the concept of the highest good, the practical postulate of God is necessary for the realization of it. The combination of virtue and happiness, let alone their perfect and exact proportionality, both for individuals and for the world as a whole, is not possible without such a postulate of God, since for Kant, virtue and happiness, as radically different elements of the highest good, are governed by different laws and true virtue can only be discerned by God. Nevertheless, this by no means entails that atheists, those who do not believe in God, cannot or should not strive for virtue and moral perfection anymore. As long as one is committed to the moral law and acts as the law commands, he can substantially contribute to realizing the highest good.

1. Introduction

Kant’s ethics is known for its emphasis on the moral law and autonomy, which naturally leads people to infer that Kant would not place too much importance on faith in God. However, in many of Kant’s works, he argues that religious belief is morally significant and he even claims that “morality inevitably leads to religion” in the preface to Religion within the Boundaries of Mere Reason (hereafter, Religion), where Kant links morality and religion with the concept of “the highest good”. Similar elucidation can be found in Critique of Pure Reason (hereafter, the first Critique), Critique of Practical Reason (hereafter, the second Critique) and Critique of Judgment (hereafter, the third Critique).1 This crucial thesis and other related viewpoints of Kant constitute his so-called “moral theism”; undoubtedly, the concept of the highest good plays an important role in Kant’s moral theism.

Unfortunately, Kant’s concept of the highest good has aroused much debate over the decades, with no consensus reached yet. Specifically, scholars’ debates center around these questions—Is the concept of the highest good an intrinsic and important element of Kant’s ethics? Or, is it, at most, an extra-moral addition (cf. Silber 1959a, 1959b, 1963; Beck 1960; Zeldin 1971; Auxter 1979; Friedman 1984)? Relatedly, is it necessary for one to believe in God if he sets the highest good as an end? Are there any other ways for one to conceive the realization of the highest good except for postulating the existence of God (cf. Denis 2003; Insole 2008)? More fundamentally, it seems that there are ambiguities in the very concept of Kant’s highest good. Then, what is the most reasonable interpretation of the highest good? Do all the various interpretations of this concept inevitably lead to religious belief (cf. Silber 1959a; Reath 1988; Lin 2019; Vatansever 2020)? Can atheists reasonably hope for and substantially contribute to the realization of the highest good? Instead, would they fall into moral despair because of their disbelief (cf. Denis 2003; Van Impe 2014)?

In this paper, I aim to argue that the highest good in Kant’s philosophy, whether it is understood as immanent or transcendent, ideal or historical, theological or secular, can only be conceived to be possible of realization through the practical postulate of the existence of God. For this reason, moral theists seem to be better off than atheists in many ways. However, this does not mean that those who do not have a faith in God cannot strive for virtue and moral perfection under the guidance of the moral law. I will propose that we can reasonably expect that, in the end, both theists and atheists can be members of the ethical commonwealth and work together to approach the approximation of the highest good.

The whole paper consists of six sections. Section 1 is an introduction. Section 2 is an examination of Kant’s elucidation (especially in Religion) of the relationship between morality and religion, in which the tenet of Kant’s moral theism and the importance of his concept of the highest good are clarified. Section 3 is an exploration of Kant’s accounts of the highest good, showing that the highest good can be understood as immanent or transcendent, theological or secular, ideal or historical, as many scholars have suggested. Section 4 and Section 5 are detailed arguments for my own position. Specifically, in Section 4, I argue that no matter how we understand and interpret Kant’s concept of the highest good, it is necessary for us to postulate the existence of God in order to conceive the possible realization of the highest good; in Section 5, I show that although moral theism seems to be a more reasonable stance than atheism given Kant’s account of the highest good, atheists can also strive for virtue and moral perfection, as long as they are guided by the moral law. And, in this sense, atheists can also contribute to the realization of the highest good, despite their disbelief in God. Section 6 is a summary and conclusion of the whole paper.

2. Kant on Morality and Religion

Kant’s thought on the relation between morality and religion is scattered in many of his philosophical writings, but it is in the first preface to Religion that he explicitly states that “on its own behalf morality in no way needs religion”2 (6:3; Rel, Kant 1998b, p. 33) and, meanwhile, that “morality inevitably leads to religion” (6:6; Rel, Kant 1998b, p. 35). At first sight, there is an obvious tension between these two claims. In this section, I will examine Kant’s elucidation of these two seemingly contradictory claims, which constitute the tenet of Kant’s moral theism, i.e., belief in God founded on morality. As we will see, the concept of the highest good plays a vital role in Kant’s moral theism.

Let’s start with Kant’s initial claim that “on its own behalf morality in no way needs religion”. (6:3; Rel, Kant 1998b, p. 33) At the beginning of the first preface to Religion, Kant says,

“So far as morality is based on the concept of the human being as one who is free but who also, just because of that, binds himself through his reason to unconditional laws, it is in need neither of the idea of another being above him in order that he recognize his duty, nor, that he observe it, of an incentive other than the law itself.”

(6:3; Rel, Kant 1998b, p. 33)

For Kant, morality is self-sufficient in that moral agents, as they are rational and free, are capable of giving a priori, unconditional laws to themselves through their own willing, without any external help. The moral law we are subject to is given to us by our own practical reason and we are obligated to act out of respect for the moral law itself. The authority of morality arises from pure practical reason itself rather than an external and divine source. We are bound to morality because of the self-giving law and we are not subject to a commanding authority outside ourselves in this regard. Moreover, since the moral law binds only through the mere form of universal lawfulness of the maxims to be adopted (“Act only in accordance with that maxim through which you can at the same time will that it become a universal law” (4:421; G, Kant 2002, p. 37)), no material determining ground is needed for morality itself. In other words, as far as morality itself is concerned, only the formal part of one’s maxims (i.e., its universal lawfulness) counts and no material element or object (e.g., purposes/ends) is needed. In this way, the autonomy of the will is highlighted in Kant’s ethics, which differentiates itself from any other moral theory based on heteronomy, especially those theological ethics that derive the authority of morality from God (cf. 4:440–41; G, Kant 2002, pp. 58–59). This naturally leads to the conclusion that, for Kant, morality on its own behalf does not need religion at all; rather, it is self-sufficient by virtue of pure practical reason.

However, as Kant continues to elucidate, he makes it clear that “morality inevitably leads to religion”. (6:6; Rel, Kant 1998b, p. 35) Kant’s argument for this claim is made by using “end” and “the highest good” as intermediary conceptions. On its own behalf, morality does not need the representation of an end for it to determine the will. In other words, for the moral law to determine the will, there is no need to refer to an end in advance. The will of rational, moral agents can abide by morality for its own sake. Nevertheless, as we are finite rational human beings, we are bound not to be indifferent to the end/purpose of our actions. As Kant puts it,

“[A]lthough on its own behalf morality does not need the representation of an end which would have to precede the determination of the will, it may well be that it has a necessary reference to such an end, not as the ground of its maxims but as a necessary consequence accepted in conformity to them.”

(6:4; Rel, Kant 1998b, p. 34)

As rational agents with practical reason, we human beings are capable of acting out of respect for the moral law, which can bring about right and virtuous conduct. Yet, as we are finite beings, we have an interest in the end/purpose of our actions and inevitably tend to ask, “what is the result of this right conduct of ours?” For example, a conscientious person may choose to do something charitable as it is her duty to do so, but she will also want to ensure that her contributions can make a difference in the world. She would reasonably hope that her charitable actions will not be in vain and will bring out the intended good ends, such as a better community or world. Taking this on board, for Kant, although consequences cannot serve as the ground for whether an action is morally right or wrong, this does not mean that human beings are not interested in the consequences of their actions. Instead, we have a natural tendency to care about the possible consequences of our actions. Our actions are always guided by their intended ends, whether it is moral ends or self-interested ends. In short, although morality itself does not need an end to determine the will, it naturally extends to the concept of an end.

In the next step, the highest good, as the ultimate end of all things, is introduced into Kant’s argument. As he puts it, “It cannot be a matter of indifference to morality, therefore, whether it does or does not fashion for itself the concept of an ultimate end of all things”. (6:5; Rel, Kant 1998b, p. 34) Here, the “ultimate end of all things” refers to the highest good in the world. It has been made clear above that we human beings have a natural interest in the ends of our actions. Every action is directed towards a specific end and different actions have different ends they aim to achieve. More specifically, for those morally significant actions conducted for the sake of duty, we can find in them both a moral end (virtue/morality) and a natural end (happiness). Now, a further question is how are these different ends related and ordered? We are not indifferent to this question, either. We need a “special point of reference for the unification of all ends” (6:5; Rel, Kant 1998b, p. 35), and this is the idea of the highest good, i.e., virtue with happiness proportioned to it (6:5; Rel, Kant 1998b, p. 34). As Kant says,

“this is indeed only the idea of an object that unites within itself the formal condition of all such ends as we ought to have (duty) with everything which is conditional upon ends we have and which conforms to duty (happiness proportioned to its observance), that is, the idea of a highest good in the world.”

(6:5; Rel, Kant 1998b, p. 34)3

As the argument goes, Kant makes a further point that for the possible realization of the highest good, we must assume or postulate a higher, moral, most holy and omnipotent being, which is God.4 The highest good is a unification of virtue and happiness proportionate to it. We can do as the moral law requires to promote our virtue and, at the same time, we long for our own happiness as the subjective ultimate end of all our actions. However, on our own, we cannot ensure that all virtuous actions can bring about proportioned happiness. Instead, we need to postulate an omnipotent moral being higher than us to assure the realization of the highest good, the union or combination of virtue and proportional happiness.

By way of summarizing the whole argument, Kant explicitly says,

“[N]ow, if the strictest observance of the moral laws is to be thought of as the cause of the ushering in of the highest good (as end), then, since human capacity does not suffice to effect happiness in the world proportionate to the worthiness to be happy, an omnipotent moral being must be assumed as ruler of the world, under whose care this would come about, i.e., morality leads inevitably to religion.”

(6:8; Rel, Kant 1998b, p. 36)

As long as we adopt the highest good as our ultimate end, we must also be committed to maintaining beliefs about the means of its realization. Since we ourselves cannot assure the attainment of perfect virtue and happiness, let alone the necessary and exact proportionality between them—only an omnipotent moral being can—our pursuit of the highest good leads us to belief in God as an assurer or guarantee. It is in this way that “morality leads inevitably to religion”.

With the above elucidation, it is evident that, for Kant, religious belief is founded on morality, not the other way around. Morality takes priority of religion in that morality is self-sufficient and no reference to religion is needed to determine what morality is. Nevertheless, we are inevitably led to step beyond the exclusive moral perspective to entertain a religious perspective when the ultimate end of our actions is taken into account. The tenet of Kant’s moral theism, in a word, is belief in God founded on morality. According to Kant, theoretical reason cannot validly prove the existence of God, so we cannot have theoretical knowledge in this regard. However, since the realization of the highest good (the ultimate end of morality) can only be possible with the postulate of an omnipotent moral being (i.e., God), we have valid practical reasons for faith in God. Clearly, this is belief or faith in God founded on morality or for moral reasons, which is moral theism.

To sum up, in this section, I examined Kant’s arguments for the two seemingly contradictory claims regarding the relationship between morality and religion, i.e., “on its own behalf morality in no way needs religion” (6:3; Rel, Kant 1998b, p. 33) and “morality inevitably leads to religion” (6:6; Rel, Kant 1998b, p. 35), which, together, form the tenet of Kant’s moral theism. My task in this section is to place Kant’s claims on the table and show the reasons he himself gives for them. However, his arguments for moral theism result in many debates, among which controversies over the very concept of the highest good are most intense. In the following two sections, I will scrutinize different interpretations of Kant’s concept of the highest good and see whether Kant’s argument for moral theism will still stand under these different interpretations.

3. Different Interpretations of Kant’s Concept of the Highest Good

As is usually understood, virtue and happiness together constitute the so-called “highest good”, which consists of “happiness distributed in exact proportion to morality (as the worth of a person and his worthiness to be happy)” (5:110; CPrR, Kant 1999, p. 229). If we take it literally, this means that if the highest good is obtained, a morally good or virtuous person can gain the happiness he deserves. His virtue is paid off by happiness and the degree of happiness he enjoys is proportional to the degree of virtue his actions display. This idea seems to be deeply rooted in the common understanding of our moral life and it seems few problems will be related to this. Nevertheless, in Kant’s philosophy, the concept of the highest good brings many interpretation problems and the importance of this concept is a highly controversial issue among scholars. So far, scholars have suggested different approaches to understanding Kant’s concept of the highest good, among which three distinctions are most influential, i.e., John Silber’s distinction between the immanent and transcendent conceptions of the highest good, Andrews Reath’s distinction between the secular and theological conceptions of the highest good, and Lara Denis’s distinction between the ideal and historical conceptions of the highest good. In this section, I will examine these three distinctions. As we will see, all of these different interpretations can be supported by corresponding texts, which shows there exist major ambiguities in Kant’s concept of the highest good.

Let’s begin with John Silber’s famous distinction between the immanent and transcendent conceptions of Kant’s highest good. As Silber puts it,

“The idea of the highest good as transcendent—that is, the idea of the highest good as the object which man is obligated to attain in full—is the measure that man uses in assessing the limits of his capacity…But the idea of the highest good as immanent—that is, the idea of the highest good as the object which man is obligated to promote to the full extent of his powers—is the measure which specifies man’s actual moral obligation.”

(Silber 1959a, pp. 484–85)

The highest good is a combination of perfect virtue and proportionate happiness. Since no man can attain perfect virtue and always reward virtue with appropriate degrees of happiness, the highest good cannot be fully realized or attained in this world on our own. As Kant says,

“Complete conformity of the will with the moral law is, however, holiness, a perfection of which no rational being of the sensible world is capable at any moment of his existence.”

(5:122; CPrR, Kant 1999, p. 238)

Moreover, human capacity does not suffice for bringing about happiness in the world proportionate to worthiness to be happy, either. In other words, perfect morality (virtue) and happiness in conformity with such perfect virtue cannot be attained in this world with our own efforts, making the full attainment or realization of the highest good impossible in this sensible, empirical world.

For the above reason, Silber suggests that the full attainment of the highest good can only be realized by postulating the existence of God and the immortality of the soul and, thus, its realization can only become possible in the transcendent, supersensible world. This leads us to the transcendent conception of the highest good, which man is obligated to attain fully and which can only be realized in another, supersensible world. Different from this transcendent conception, the immanent conception of the highest good refers to virtue plus proportionate happiness, which man is capable of promoting (not attaining) in this world. According to the immanent conception of the highest good, we are not morally obligated to attain fully the highest good; rather, we are obligated to take this idea as an ideal, “as a model for the determination of our wills”, and we have “a duty to realize the highest good as far as it lies within our power to do so” (Silber 1959a, p. 478). Therefore, when the highest good is understood as immanent, which can be conceived in this world, our duty is not to attain but to promote it.

In a word, with Silber’s distinction, Kant’s conception of the highest good can either be understood as transcendent or immanent. When Kant asserts that it is man’s duty to fully attain the highest good, he stresses the transcendence of the highest good, since perfect virtue with proportionate happiness cannot be fully attained in this world. It transcends the sensible world and can only be realized in a transcendent, supersensible world. When Kant asserts that it is man’s duty merely to promote the highest good to the full extent of his power, what he has in mind is an immanent conception of the highest good, which we are capable of promoting and approximating with our constant moral efforts in this world.

Another important and influential distinction is made by Andrews Reath, who suggests that Kant’s texts reveal two different conceptions of the highest good, i.e., a “theological” conception and a “secular” conception. According to Reath,

“[T]he important feature of a theological conception of Highest Good is that it would be a state of affairs that comes about in another world through the activity of God. By contrast, a secular conception of the Highest Good can be described entirely in naturalistic terms, as a state of affairs to be achieved in this world, through human activity.”

(Reath 1988, p. 601)

For Reath, the theological conception of the highest good has two requirements. First, all individuals are virtuous and, second, happiness is distributed in exact proportion to virtue (cf. Reath 1988, p. 602). As explained above, since no man can attain perfect virtue in the empirical world and no man can assure exact happiness proportionate to virtue, these two requirements cannot be satisfied in the sensible, empirical world. Naturally, the theological conception of the highest good sets an otherworldly goal and it can only be realized in another higher world with practical, theological postulates. Reath himself does not favor the theological conception and he thinks this conception cannot be supported by Kant’s philosophy internally. He believes it “represents a departure from Kant’s basic principles” (Reath 1988, p. 613).

According to Reath, the secular conception of the highest good represents Kant’s mature view of the highest good (cf. Reath 1988, p. 601). Understood as a secular conception, the highest good is a union or combination of virtue and happiness, where happiness is subordinated to virtue (cf. Reath 1988, p. 605). This conception does not stress the necessary, exact proportionality between virtue and happiness. Instead, it only requires that happiness be “conditioned by” or “subordinated to” virtue, i.e., morality should take priority over happiness in their combination, as the moral law commands. As Reath suggests, such a combination of happiness and virtue can be achieved through mere human agency in this world without divine assistance, leading us to a secular conception of the highest good (cf. Reath 1988, pp. 615–16). For example, people can establish just social institutions to support moral conduct and the realization of various moral ends, where the happiness of all would be the natural result.

Clearly, Silber’s distinction between the transcendent and immanent conceptions of the highest good is related to Reath’s distinction between the theological and secular conceptions of the highest good. Loosely speaking, taken as the exact and perfect proportionality between virtue and happiness, the highest good should be understood as transcendent and theological, since this can only be conceived to be possible in a supersensible world with the postulate of the existence of God and the immortality of the soul. By contrast, understood as an immanent conception, the highest good should be possible in this world with our moral efforts. Although Silber does not explicitly explain the immanent conception as secular, since everyone is obligated to promote the immanent highest good by acting morally and creating a world with justice, the immanent conception of the highest good is, indeed, secular.

Apart from the above two distinctions of Kant’s conceptions of the highest good, Lara Denis makes a distinction between the ideal conception of the highest good and the historical conception of the highest good. According to Denis, the ideal version of the highest good “is understood as including happiness perfectly proportionate to, and caused by, virtue” (Denis 2003, p. 202). In contrast, the historical notion of the highest good “describes the highest good as a state of affairs resulting from human moral, historical and political progress”, which “consists in a world of virtue, justice, happiness, and flourishing rational capacities” (Denis 2003, p. 202). In other words, the ideal highest good consists in the ideal, perfect proportionality between virtue and happiness, which is unattainable without theological faith. By contrast, in the historical conception of the highest good, only the conformity (not perfect proportionality) of happiness with moral conduct is emphasized and it is attainable in the historical progress of human society.

Denis stresses the importance of the historical conception of the highest good and believes “it is an end reason sets for us collectively to pursue through social and political means” (Denis 2003, p. 212). As Denis suggests, since this historical conception of the highest good does not depend on divine agency or immortality for its completion, it better serves as an end for our moral conduct. Compared with the ideal conception, the historical or social conception of the highest good gives us a goal within the scope of human agency (cf. Denis 2003, p. 212).

As it becomes clear, Denis’s distinction between the ideal and historical conceptions of the highest good is also closely intertwined with Reath’s distinction between the theological and secular conceptions of the highest good. In a sense, the theological conception of the highest good is ideal, while the secular conception is historical. As a matter of fact, when Reath differentiates the theological conception and the secular conception of the highest good, he explains that the secular conception is historical or social. For example, Reath explicitly says,

“Turning now to the secular conception, this version treats the Highest Good as a social goal to be achieved in history, through human agency and the ordering of social institutions.”

(Reath 1988, p. 603)

Similarly, Denis argues that if we adopt the historical account as a legitimate conception of the highest good, even those metaphysically conservative dogmatic atheists can maintain hope for the realization of the highest good (cf. Denis 2003, p. 213). This clearly shows that what Denis has in mind is a historical, social and secular conception of the highest good.

The above discussion suggests there are significant ambiguities in Kant’s elucidation of the concept of the highest good. In some places, Kant refers to the highest good as perfect virtue with exact proportionality of happiness. For example, in the second Critique, Kant says,

“virtue and happiness together constitute possession of the highest good in a person, and happiness distributed in exact proportion to morality (as the worth of a person and his worthiness to be happy) constitutes the highest good of a possible world.”

(5:110; CPrR, Kant 1999, p. 229)

Understood as a perfect, ideal conception, which consists in perfect virtue together with happiness distributed in exact proportion to morality, the highest good can only be attained in another transcendent world with divine assistance, which leads us to a transcendent and theological conception of the highest good. In other places, however, it seems Kant’s conception of the highest good is immanent, secular and historical. For instance, in the third Critique, Kant suggests that the highest good is “the existence of rational beings under moral laws” (5:444; CJ, Kant 2007, p. 273) and that the final end “is the highest good in the world possible through freedom” and moral law makes it obligatory for us to strive towards the attainment of this highest good (cf. 5:450; CJ, Kant 2007, p. 278). Significantly, Kant makes it clear that our duty is to promote this end and that “the fulfillment of duty consists in the form of the earnest will, not in the intervening causes that contribute to success” (5:451; CJ, Kant 2007, p. 280).

Now, a natural question is, if the highest good is understood as immanent, secular and historical, can Kant’s argument for “morality leads inevitably to religion” still stand? To put it in another way, if we adopt the immanent, secular and historical conception of the highest good, is it still necessary for us to postulate the existence of God for the realization of the highest good? At first sight, it seems the answer is negative. In fact, Silber, Reath and Denis’s uses of the words “immanent”, “secular” and “historical” suggest that they believe the highest good understood in these ways can be realized in this world with man’s own effort in the process of history. All of them intend to stress the non-theological sense of Kant’s concept of the highest good and seek to show how we human beings can contribute to realizing the highest good. Based on their distinction, it seems that no divine aid is needed to realize the immanent, secular and historical conception of the highest good. It is at this point that I disagree with them. In the next section, I will explain why even the so-called immanent, secular and historical conception of the highest good can only be conceived to be possible of realization by postulating the existence of God.

4. God as a Necessary Practical Postulate for the Realization of the Highest Good

As our discussion in the previous two sections suggests, the concept of the highest good plays a critically important role in Kant’s moral theism. The highest good is set as the final end of morality, which we are obligated to pursue. Since human capacity does not suffice for bringing about happiness in the world proportionate to worthiness to be happy, an omnipotent moral being must be postulated as the ruler of the world, under whose care the balance between happiness and virtue occurs. Nevertheless, Kant’s concept of the highest good can be understood in different ways, as is shown in the last section. Specifically, as Silber, Reath and Denis suggest, Kant’s texts reveal a “transcendent, theological and ideal” conception of the highest good and an “immanent, secular and historical” conception of the highest good. Understood as a transcendent, theological and ideal conception, the highest good refers to perfect virtue with exact proportionality of corresponding happiness, whose full realization can only be possible with the practical postulates of the existence of God. This point is well founded and can hardly be refuted. However, when understood as an immanent, secular and historical conception, it seems that the highest good can be promoted and realized with our own efforts in this world without the assistance of a higher being. Can this point be justified? In this section, I will argue that it is not. As we will see, human beings are obligated to pursue and promote the highest good in this world with constant moral efforts, but the realization of the highest good can only be reasonably conceived with belief or faith in God, even when the highest good is understood as immanent and historical.

The first reason for this lies in the fact that virtue and happiness are heterogeneous and their connection cannot be guaranteed analytically. As Kant says,

“[T]he maxims of virtue and those of one’s own happiness are quite heterogeneous with respect to their supreme practical principle; and, even though they belong to one highest good, so as to make it possible, yet they are so far from coinciding that they greatly restrict and infringe upon each other in the same subject.”

(5:112; CPrR, Kant 1999, p. 230)

That is, virtue and happiness do not necessarily contain one another—they even “greatly restrict and infringe upon each other in the same subject” (5:112; CPrR, Kant 1999, p. 230). If one follows the moral law and attains virtue, he is not automatically or necessarily happy. At the same time, if one seeks his own happiness and succeeds in obtaining it, he is not for this reason necessarily virtuous.

But, for Kant, the highest good must contain two elements, i.e., virtue and happiness. Both are the good we pursue. Virtue is moral good, which is the non-empirical constituent of the highest good, while happiness is non-moral good, which is the empirical constituent of the highest good. In the highest good, virtue is the unconditioned good and it is “the supreme condition of whatever can even seem to us desirable and hence of all our pursuit of happiness” (5:110; CPrR, Kant 1999, p. 228). To promote the highest good, we can make earnest efforts to act morally and strive for virtue. But virtue alone is not yet the highest good for us finite rational beings. Happiness is also required.

Nevertheless, after we have tried our best to approach true virtue, happiness does not necessarily and naturally follow our virtuous actions and characters. Then, how can we reasonably hope for happiness and the attainment of the highest good? Can the highest good become possible merely through social or political means in the historical progress of human society, as Denis suggests?

After all, it seems that by establishing just states and enacting just laws, we can reward the virtuous and punish the vicious, which can substantially promote social justice. Living in a good society, we can reasonably hope that our virtuous actions will be paid off by corresponding happiness and that virtue and happiness can combine in a certain way with human agency. This seems to indicate that the so-called “historical and secular” highest good, understood as the combination or union of virtue and happiness in which happiness is subjected to virtue, can be promoted and realized in secular ways without any divine assistance.

However, as I will show, this is not the case. Even if we do not emphasize the exact or perfect proportionality between virtue and happiness (which is ideal), the highest good cannot be assured either without an omnipotent moral being. According to the so-called “secular” or “historical” conception of the highest good, the necessary and exact proportionality between virtue and happiness is not required for the attainment of the highest good. But it still requires that happiness be “conditioned by” or “subordinated to” virtue. To fulfill this requirement, we have to first ascertain true virtue in a man, before we can ensure that his happiness is, indeed, conditioned by or subordinated to virtue.

But how can we ascertain that? Some people may suggest that we can ascertain true virtue in a man through his actions. But, according to Kant, although actions can display virtue, virtue does not consist in external actions. In Metaphysics of Morals, Kant defines virtue as “the strength of a human being’s maxims in fulfilling his duty” (6:394; MM, Kant 1999, p. 524). That is to say, whether there is virtue in a man is determined by the internal maxims according to which his actions are performed. Now, how can we be certain on what kind of internal maxims a man’s actions are based?

As finite human beings, we do not have intellectual intuition and, thus, one cannot penetrate into man’s mind, including one’s own. Kant says,

“[T]hrough experience we can indeed notice unlawful actions, and also notice (at least within ourselves) that they are consciously contrary to law. But we cannot observe maxims, we cannot do so unproblematically even within ourselves.”

(6:20; Rel, Kant 1998b, p. 46)

Here, Kant is discussing unlawful actions contrary to the moral law, but we can reasonably infer that the case is similar to the lawful actions, which conform with the moral law. As Kant himself explicitly puts it,

“[A] human being cannot see into the depths of his own heart so as to be quite certain, in even a single action, of the purity of his moral intention and the sincerity of his disposition, even when he has no doubt about the legality of the action.”

(6:392; MM, Kant 1999, p. 523)

In a word,

“The real morality of actions (their merit and guilt), even that of our own conduct, therefore remains entirely hidden from us.”

(A551/B579; CPR, Kant 1998a, p. 542)

If Kant is right on this point, then we can never be certain on what kind of maxims a man’s actions are based. For this reason, the first element of the highest good (virtue) cannot be fully discerned all on our own or by any external social institutions. Instead, only an all-knowing, all-powerful and all-good God with intellectual intuition can penetrate into man’s mind, making Him the only one to know our maxims and discern whether we are truly virtuous. Based on this, God can distribute proportionate happiness according to one’s virtue, which leads to the realization of the highest good in individuals. On the contrary, social institutions seem to be able to reward the virtuous and punish the vicious; still, since they cannot truly discern virtue, their distribution of happiness or unhappiness is not well founded. This clearly shows that without divine assistance, the highest good for individuals cannot be authentically promoted or realized by social institutions.

What’s more, for the society/the world as a whole, only by postulating the existence of God can we hope that social goods could be promoted in the long run and that the highest good for the whole world can be possible in the future.5 For the highest good for the whole world to be possible, the mere combinations of virtue and happiness in some individuals are no longer enough. Rather, to promote the highest good for the whole world, we should combine universal happiness with the most lawful morality of all rational beings in the world. In other words, only when everyone in the world obtains genuine virtue and is, at the same time, blessed with proportionate happiness can the highest good of the world be promoted. In Religion, Kant suggests that such universal highest good consists not only in the fact that the universal happiness of everyone conforms with their virtue, but also in a special constitution among them, namely an ethical community, which is “a universal republic based on the laws of virtue” (6:98; Rel, Kant 1998b, p. 109). Striving for one’s own moral perfection does not suffice for the realization of the highest good of the world; rather, this conception requires the union of all the individuals into a whole towards a common end. We have a duty to promote the highest good of the world, but we are not capable of doing this all on our own. Instead, only by presupposing or postulating God can we conceive the world as a whole is developing towards the idea of the highest good. As Kant says,

“this duty will need the presupposition of another idea, namely, of a higher moral being through whose universal organization the forces of single individuals, insufficient on their own, are united for a common effect.”

(6:98; Rel, Kant 1998b, p. 109)

With the above discussion, we see that, within the framework of Kant’s philosophy, no matter how we interpretate the concept of the highest good, God must be postulated for the realization of the highest good. The combination of virtue and happiness (let alone their perfect and exact proportionality), both for individuals and for the world as a whole, is not possible without postulating the existence of God, since virtue and happiness are two very different elements, governed by different laws, and true virtue can only be discerned by God. This, again, leads us to the tenet of Kant’s moral theism, i.e., our faith in God is grounded on morality. Since we are obligated to promote the highest good in our own person and in the whole world and since the highest good is only possible by postulating the existence of God, we are led to develop a faith in God for moral reasons.

5. Virtue and Moral Perfection for Atheists

Now, we get to the point that for Kant God is a necessary practical postulate for the highest good to be possible. This being said, it seems that moral theists who have faith in God grounded on morality are better off than atheists who do not believe in God, since the former can hope for the realization of the highest good while the latter cannot.6 Nevertheless, as I will argue in this section, this does not entail that atheists cannot contribute to the realization of the highest good anymore. Despite their disbelief in God, atheists should and can still strive for virtue and moral perfection under the guidance of the moral law. In this way, atheists can also substantially contribute to realizing the highest good.

Before we get to our central point, we should make it clear that Kant distinguishes two kinds of atheism, i.e., skeptical atheism and dogmatic atheism. As Kant explains,

“Atheism (that is, godlessness or denial of God), can be either skeptical or dogmatic. The former disputes only the proofs for the existence of a God and especially their apodictic certainty, but not God’s existence itself, or at least its possibility. Hence a skeptical atheist can still have religion, because he sincerely admits that it is even more impossible to prove that God does not exist than to prove that he does…It is wholly different with the atheist who straightway denies the existence of a God, and who declares in general that it is impossible for there to be a God.”

(Kant 1978, pp. 39–40)

According to Kant, skeptical atheists are right to reject speculative proofs for the existence of God and he believes that the existence of God can only be postulated through practical, moral argument, as our above discussion suggests. Moreover, for skeptical atheists, since speculative arguments do not refute God’s existence, this may allow them to affirm a belief in God based on moral considerations. To use Kant’s own words,

“[A] skeptical atheist can still have religion.”

(Kant 1978, p. 39)

By contrast, dogmatic atheists deny the existence of God straightforwardly and it is impossible for them to have faith in God. For Kant, it is dogmatic atheism that should be contrasted with moral theism, while skeptical atheism and moral theism can find common ground, since it is possible for skeptical atheists to have a belief in God based on moral reasons. In the following discussion, we will not distinguish skeptical atheists and dogmatic atheists. We will use “atheists” in the common sense to refer to those who do not manifest faith in God. After all, in the sense that both skeptical atheists and dogmatic atheists do not publicly confirm or declare the existence of God, they are atheists as we generally understand.

For Kant, without believing in God, atheists cannot conceive the possible realization of the highest good, the pursuit of which is command by the moral law. This might lead atheists, who embrace Kant’s philosophy at the same time, to regard pursuing the highest good as irrational, but this will not necessarily weaken one’s respect for the moral law. Instead, every rational human being, including atheists, is subject to the moral law and is obligated to do what the law commands. In the pursuit of the highest good, what we human beings (be it theists or atheists) are capable of doing is perfecting our virtue to the limits of our ability. That is, there is at least one constituent of the highest good, i.e., virtue, that human beings can strive for.

Virtue, as Kant suggests, is the “moral strength of a human being’s will in fulfilling his duty, a moral constraint through his own lawgiving reason, insofar as this constitutes itself an authority executing the law” (6:405; MM, Kant 1999, p. 533). The moral law we are subject to is what reason gives to itself, so the reason is self-lawgiving. This law is unconditional and universally valid for all rational beings, both complete, holy rational beings and finite rational beings. The will of fully rational beings is holy, which will not be affected by irrational factors and will conform with the law necessarily. On the contrary, human beings are not fully rational beings and we do not have a holy will. Instead, we also have natural inclinations, which may conflict with our reason. For this reason, human beings will not automatically and necessarily act as the moral law commands. Still, the moral law commands unconditionally and it is a duty for human beings to keep their action accord with the law and adopt maxims of the action out of respect for the law.

Moreover, duty involves moral constraint or practical necessitation in that the moral law categorially commands us to abide by it, no matter how reluctantly our actions may be performed. As Kant says,

“The moral law is, …for the will of every finite rational being a law of duty, of moral necessitation and of the determination of his actions through respect for this law and reverence for his duty.”

(5:82; CPrR, Kant 1999, p. 206)

This being said, for us finite rational beings to fulfill our duty, it is necessary to fight against the immoral incentives or the enemies of virtue, which calls for strength of the will. This is why Kant defines virtue as “the moral strength of the human being’s will in fulfilling his duty”. Virtue is not for infinite or complete rational beings; rather, it is only for human beings as finite rational beings.

Every human being, as far as they are endowed with reason, is subject to the supreme moral law and atheists are no exception. As finite rational beings, atheists also have a duty to act as the moral law commands and strive for virtue as far as they can. More specifically, when Kant elucidates the duties of virtue in his Tugendlehre, he makes it clear that it is a human being’s duty to increase his moral perfection by purifying one’s disposition to duty and perfecting himself constantly. The commands can be put as “be holy” and “be perfect”, respectively (6:446; MM, Kant 1999, p. 566). Holiness and perfection can by no means be attained by finite rational beings, but the moral law still commands us to strive after them. For human beings, striving for virtue and moral perfection is an ongoing project, in which only constant progress can be made. As Kant puts it,

“Virtue is always in progress and yet always starts from the beginning.—It is always in progress because, considered objectively, it is an ideal and unattainable, while yet constant approximation to it is a duty. That it always starts from the beginning has a subjective basis in human nature, which is affected by inclinations because of which virtue can never settle down in peace and quiet with its maxims adopted once and for all but, if it is not rising, is unavoidably sinking.”

(6:409; MM, Kant 1999, p. 537)

The reason why virtue and moral perfection is an endless project for human beings lies in the facts about human nature. As Kant elucidates in Religion, although there exist original predispositions to good in human nature (animality, humanity, personality), the propensity to evil in human nature is also innate. Kant explains three different grades of the natural propensity to evil, i.e., frailty, impurity and depravity, among which depravity is the worst and Kant calls it “the radical evil” in human nature. Very importantly, Kant attempts to show that the propensity for evil is established in all human beings, even the best ones. In other words, the propensity for evil among human beings is universal and it is woven into human nature (cf. 6:29–30; Rel, Kant 1998b, pp. 52–54). Moreover, since such propensity to evil is innate in human nature and it cannot be eradicated or entirely extirpated through human forces, human beings should live with it and pursue possible virtue and moral perfection on this basis. That is why striving for virtue is always in progress and always starts from the beginning. No one can rest assured that he needs not fight against the propensity to evil in human nature anymore and that he has obtained true virtue or complete moral perfection.

What we have said above applies to all human beings, including atheists. In fact, when Kant elucidates virtue and moral perfection, he never divides human beings into different groups. Rather, to recapitulate, the moral law is valid and unconditionally authoritative for all rational beings and every human being has a duty to act as the law commands, to pursue virtue and one’s own moral perfection. This being said, atheists also have a duty to take the moral law as the supreme guide of their action and try their best be strive for virtue. As we can reasonably infer, as long as an atheist is committed to the moral law and act as the law commands, he/she is making a substantial contribution to realize the highest good in his/her person and in the world as a whole. After all, in the pursuit of the highest good, all we human beings can do is strive for virtue as far as we can. As for the other constituent, i.e., happiness, we can only hope for another higher being’s fair and just distribution according to our true virtue. Because of their disbelief in such a higher moral being, atheists might be deprived of such hope of the possible realization of the highest good. Nevertheless, as long as they strive for their own virtue and moral perfection, they can also substantially contribute to the approximation of the highest good, whether they themselves are aware of this or not.

6. Conclusions

The concept of the highest good plays a vital role in Kant’s argument for moral theism, which is the belief in God founded on morality or for moral reasons. Nevertheless, there are important interpretation ambiguities related to the very concept of the highest good. More specifically, it can either be understood as transcendent, theological and ideal or be understood as immanent, secular and historical. Our discussion in this paper suggests that, as far as we adhere to Kant’s philosophy, no matter how we understand the concept of the highest good, it is necessary to postulate the existence of God for us to conceive the realization of the highest good. The main reason for this is that virtue and happiness are two very different goods governed by different laws and that true virtue can only be discerned by an all-knowing, all-powerful and all-good being. Only God can allocate happiness according to one’s true virtue. However, as our discussion shows, this does not entail that atheists should not and cannot strive for virtue and moral perfection anymore. As long as everyone respects the moral law and acts as the moral law commands, both moral theists and atheists can work together to contribute to the realization of the highest good.