1 1 Kant’s Ethical Theory: An Overview

Kant’s writings on ethics followed his monumental Critique of Pure Reason (1781). There he tried to show that all previous metaphysical theories failed because they did not begin with a critical assessment of the powers of reason. His own critical study attempted to revolutionize metaphysics and synthesize the best from rationalist and empiricist traditions. A major conclusion relevant to ethics was that theoretical reason cannot prove the existence of God, immortality, or freedom of the will, though it leaves room for faith. In his later ethical writings he argued that nevertheless from practical reason we can establish the supreme principle of morality and the freedom of choice that it presupposes. At least, he argued, these can be shown to be valid for purposes of deliberation and action. These are major themes of his classic Groundwork for the Metaphysics of Morals (1785). Here he also defends his a priori method for the foundations of ethics, draws a sharp contrast between moral and nonmoral “ought” judgments, and articulates several versions of the supreme moral principle. Shortly after, in his Critique of Practical Reason (1788), he reaffirms his previous conclusions but modifies his argument. Here he also offers moral reasons for faith that God exists and hope for immortality, but not as a basis or motive for morality. Later Kant published The Metaphysics of Morals (1797–8), which (in Part I) presents his theory of law and justice and (in Part II) explains how his ethical principles apply to recurrent moral issues. Contemporary philosophers have interpreted Kant’s ethical writings in many different ways. This chapter simply highlights some of the main themes, inviting readers to explore them further for themselves.

When addressing the most fundamental questions, Kant argues, moral philosophy should be “pure” and not based on empirical generalizations. For example, the validity of its basic principle should not depend on how altruistic or selfish human beings are naturally inclined to be. In Kant’s view, pure moral philosophy aims first to discover the most basic and comprehensive moral principle inherent in ordinary thought about moral duty and morally worthy actions. This requires what he called an analytic mode of argument, which is a matter of examining our concepts carefully to see what further ideas they presuppose. The conclusion of such arguments is always conditional. For example, in Groundwork II, Kant argues not that the supreme moral principle (which he calls “the Categorical Imperative”) is rationally binding for us, but only that in believing that we have genuine moral duties we are necessarily committed to the Categorical Imperative as a rationally imperative moral principle.

Pure moral philosophy also aims to determine whether or not conformity to the basic moral principle is necessarily rational, and this is not a question that can be settled by empirical studies of how people actually behave. Even polls about what people say is rational would be inconclusive because the claim that violations of moral requirements are contrary to reason is a normative claim. It is a claim about what in fact we have good and sufficient reason to do, which is more than a prediction about what most people would say if asked. To establish that the basic moral principle is rationally binding, Kant says, requires a different type of argument, one that proceeds synthetically. This is what he attempts in the notoriously dense reasoning in Groundwork III. Here the question is not about what is presupposed by our common moral beliefs but about whether we have sufficient reason to regard those beliefs as true. Both questions, in Kant’s view, call for an a priori method. Groundwork II uses an a priori analytical argument to show that our moral beliefs presuppose that moral requirements are rational, but Groundwork III uses a different (“synthetical”) a priori procedure to show that this presupposition is not an illusion.

None of this implies, however, that ethics is completely independent of empirical facts. Most obviously, we cannot make judgments about what we ought to do on a particular occasion without some information about the situation. Even general principles of the sort Kant presents in The Metaphysics of Morals depend on at least general facts about the human condition. Kant does defend the controversial claim that some principles (for example, the prohibition of lying) are binding regardless of the particular circumstances, but he acknowledges that the application of other principles (for example, those regarding giving aid, developing one’s talents, and even retributive punishment) may vary with the situation. When moral philosophy focuses on empirical facts, such as the conditions that facilitate moral education, he calls it moral anthropology.

In Kant’s view, it is crucial to distinguish between morality and prudence. Too often, in theory and in practice, we confuse moral reasons with self-serving reasons. Philosophers mistakenly urge us to be moral as a means to happiness, and in daily life we make exceptions of ourselves by treating our strong self-regarding desires as excuses. At the heart of Kant’s moral theory is his explanation of the contrast between moral and nonmoral “ought” judgments. The former express (or are based on) categorical imperatives whereas the latter express (or are based on) hypothetical imperatives. All imperatives (in Kant’s sense) have two features: they are (at least conditionally) rational to follow and they are expressed in terms appropriate for those who can follow them but might not (“ought,” “should,” “must,” “Do it!”). Categorical imperatives are said to be unconditionally necessary “commands” of reason that prescribe an act as good in itself. They express the idea that we (rationally) must do as prescribed whether or not it will contribute to our happiness or serve the particular ends we happen to have. Hypothetical imperatives, by contrast, are “counsels of prudence” or “rules of skill” that prescribe an act as (conditionally) good to do if or because it serves as a means to our happiness or particular ends we happen to have. Strictly speaking, Kant argues, there is only one Categorical Imperative—the most basic principle of rational morality (to be discussed shortly)—but he also used the term for strict requirements that are based on this basic principle.

Characteristic examples of specific categorical imperatives, in Kant’s view, include “One must not make false promises,” “Do not treat anyone as worthless,” and “Adopt the happiness of others as an end.” The idea is that failing to conform to these moral principles is contrary to reason (“irrational” or “unreasonable,” we might say) and, in Kant’s view, this is not because these failures would make us unhappy or unable to achieve what we want. Examples of hypothetical imperatives might include “One ought to floss one’s teeth if one aims to avoid gum disease,” “Work out harder!” (assuming you aim to be successful in sports), “Since you want to be happy, you should avoid dwelling on past troubles,” and “Save something for a rainy day!” (where the implicit reason is that you will be unhappy otherwise). The idea in these cases is that it is one’s particular aim or general concern to be happy that explains why it is rationally necessary to act as the hypothetical imperatives prescribe—unless there is a compelling (perhaps moral) reason not to.

Why are certain facts reasons to act and others are not? Kant treats facts as reasons insofar as they would fit appropriately into a pattern of reasoning governed by a general principle of rational choice. In the case of hypothetical imperatives the general principle seems to be something like this: You ought, if you aim for a certain end, to take the necessary means to it—or else give up the end. This principle picks out certain facts as reasons to act—or at least to modify one’s plans. For example, it identifies as reasons the (joint) facts that you aim to be successful at sports and exercising harder is needed to accomplish that goal. These reasons do not make the exercise absolutely mandatory, of course, because you may have good reason to give up your plan to succeed at sports. Our natural desire for happiness (lasting contentment and achieving our desire-based ends) cannot be altogether given up, Kant thought, but we can choose not to pursue happiness as our end on particular occasions when there is sufficient reason (for example, a moral imperative) to choose otherwise. In addition, Kant reminds us, how we conceive of our happiness is vague and our understanding of how to achieve it is uncertain. Prudence, then, only gives us conditionally rational “counsels,” not strict “commands,” which are only given by categorical imperatives.

When we turn to categorical imperatives, what is the rational principle that identifies compelling reasons to act? Kant thinks that there must be such a principle and it must be a basic Categorical Imperative in the strictest sense—an absolutely unconditional and nonderivative rational principle. His thought is that the existence of particular moral requirements, which we all recognize, presupposes that there is such a principle. How else, for example, could it be (as he assumed) that there are unconditional commands of reason not to make false promises for profit, to commit murder for revenge, or to ignore the welfare of others? The main aims of the Groundwork were to articulate and vindicate our reliance on this presupposed rational principle, the Categorical Imperative.

Given Kant’s a priori methodology and arguments so far, this supreme moral principle must have compelling credentials as a necessary form or standard that should shape all rational deliberation and choice about practical matters. Too often rationalist theologians and philosophers had uncritically declared their substantive moral dictates to be the voice of reason, but the aim of Kant’s critical philosophy was to expose false pretensions in such claims to rational authority and, when possible, to vindicate the proper use of practical reason. The supreme moral principle, however, must also be plausible as a standard presupposed in common moral thought, for example, in our general understanding of the differences between duty and self-interest and in our ability to distinguish right from wrong in particular cases. Because the Categorical Imperative must be the supreme principle of practical reason as well as of morality, we should not be surprised, even if initially disappointed, to find that what it prescribes is essentially that we fully respect the development and exercise of the powers of practical reason in each person. The formulations of this requirement vary as analysis reveals its more specific meaning.

The most general idea Kant is working with here is that good (moral and rational) choice is constrained and guided by the necessity “to conform to universal law.” “Universal law” here is by definition a necessary requirement of reason that guides the conduct of any fully rational agent and, in imperative form, is an inherent standard unavoidably recognized by all imperfectly rational human beings. So assuming that there are universal laws, the imperative “Conform to universal law” in this sense should be uncontroversial. In two controversial moves, however, Kant argues that from this basic idea we may infer his famous formula of universal law:

(FUL): Act only on that maxim by which you can at the same time will that it should become universal law. (Kant (1785), 4: 421)

This is followed immediately by a variation, the formula of a universal law of nature:

(FULN): Act as though the maxim of your action were to become by your will a universal law of nature. (Ibid.)

Kant illustrates the use of FULN, and so (indirectly) FUL, with four examples: suicide to escape a troublesome life, borrowing money with a lying promise to ease financial problems, not doing anything to develop one’s useful talents, and refusing to give any help to others in trouble. Agents can determine the wrongness of these acts and omissions, Kant argues, by using FULN to test the maxim (intention or policy) on which they propose to act.

Scholars differ on how exactly these formulas are supposed to guide moral deliberation. It is clear, however, that any application must begin by identifying the maxim of a proposed act. This is meant to be an honest articulation of what one intends to do and why: for example, “I intend to do this (e.g. borrow money that I know I cannot repay) for a certain purpose (e.g. to pay for an expensive holiday) because I care more for my pleasure than the rights and interests of the lender.” Problems arise because there may be several different ways of expressing the maxim, but in any case the next step is to try to conceive of the maxim as a universal law (or law of nature). This has been variously interpreted as a teleological law, a psychological law, or a law of permission: that is, we are to conceive a possible world in which one’s purposeful act fits into a system of natural purposes, a world where everyone does act on the maxim, or a world where anyone may do so. Maxims that cannot without contradiction be conceived as universal laws in the appropriate sense are deemed wrong to act on. Some maxims, however, can be conceived as universal laws but not willed as universal laws. Kant’s examples are neglecting one’s talents and refusing to give aid to those in dire need. Acting on these maxims too is deemed wrong, though Kant calls the duties to develop one’s talents and help those in need “imperfect duties” by contrast to “perfect duties” such as not to make lying promises.

Kant’s followers and critics have long debated whether proper application of FUL and FULN really leads to moral judgments that are correct and compatible with common understanding. Many scholars now doubt that it is important to Kant’s basic moral theory that these formulas function as explicit decision-guides regarding particular cases. As Kant sometimes suggests, they may serve as heuristic aids to help us see more clearly that what we propose to do is contrary to principles we already accept and apply to others. Because we are tempted to make illegitimate exceptions for ourselves, reflecting on a world where everyone does (or may) act as we intend can help to expose our self-deceiving excuses. Another idea is that the formulas (with later formulations of the Categorical Imperative) provide a framework or perspective for thinking about very general moral principles rather than deciding particular cases. These would be, for example, the ethical principles of the sort Kant proposes in The Metaphysics of Morals: “Do not violate the (legal) rights of others,” “Respect every human being as a person,” “Seek your own natural and moral perfection,” and “Promote the happiness of others.”

Regarding the importance of examples, Kant repeatedly insists that the basic moral principle cannot be identified or established as rational by appeal to examples, but he also expresses confidence that ordinary people have a basic knowledge of right and wrong that implicitly relies on the ideas expressed in his formulations of Categorical Imperative. For this reason Kant suggests that careful use of his formulas in moral judgment would “clarify” and “strongly confirm” his claims about the supreme moral principle (Kant (2002), 194 [4: 392]).

The universal law formulas are concerned with the “form” of moral maxims, but Kant’s next formulation of the Categorical Imperative concerns their “matter” or “end.” He states this formula of humanity as an end thus:

(FHE): Act in such a way that you treat humanity, whether in your own person or in any other person, always at the same time as an end, never merely as a means. (Kant (2002), 230 [4: 429])

The idea of expressing the essential features of morality in terms of means and ends was not original to Kant but he used it in a way that contrasts with many traditional moral theories. These “teleological” theories tried to describe the ideal end or goal of a moral life and viewed specific virtues and constraints as necessary means to achieve that goal (and sometimes as constitutive elements presupposed in the goal itself). For Kant, rational nature (“humanity”) in each person is an end in itself in a special sense, not as a goal to be achieved but as a status to be respected. It limits the legitimate pursuit of personal and social ends, Kant argues, by prohibiting the use of certain means (for example, lying promises and revolution) and also by requiring us to adopt and pursue certain moral ends (the perfection of oneself and the happiness of others).

Specific interpretations of this formula vary. For example, some understand FHE as just a different way of expressing the same requirement as the universal law formulas, that is, a maxim is permissible only if it can be willed consistently as universal law by anyone, whether on the “giving” or “receiving” end of a transaction. For example, the maxim of a lying promise would have to be rationally acceptable, not only to the deceiver, but also to the person deceived. Often the formula of humanity is assumed to be an intuitive guide to be used case by case, ruling out proposed acts that seem not to respect each person as a rational agent. A more formal reading treats the formula as an abstract requirement to honor the rational (“law-making”) will in each person, as later understood through the formula of autonomy and the formula of the kingdom of ends. Any principle’s alleged exceptions need to be ultimately justifiable from a perspective that takes appropriate account of the rational will of every person, especially those who are harmed or thwarted in their pursuits for the sake of others. In discussing ethical duties in The Metaphysics of Morals, Kant seems to appeal to a more substantive standard, suggesting that to treat humanity as an end implies strong (though not always absolute) presumptions in favor of preserving, developing, exercising, and honoring rational capacities in oneself and others.

From the previous formulations, Kant says, a third one follows. This formula of autonomy is expressed in several ways, including:

(FA): …the supreme condition of the will’s harmony with universal practical reason is the Idea of the will of every rational being as a will that legislates universal law…[; and] every human will is a will that enacts universal laws in all its maxims…(Kant (2002), 232–3 [4: 431–2])

This formula of autonomy, Kant says, leads to the “very fruitful concept” of a kingdom (or commonwealth) of ends, and he uses this concept to re-express the idea of autonomy in a variation often understood as a separate principle—the formula of a kingdom of ends. Kant expresses this as follows:

(FKE): A rational being must always regard himself as lawgiving in a kingdom of ends made possible through freedom of the will…[and] [a]ll maxims which stem from autonomous lawgiving are to harmonize with a possible kingdom of ends and a kingdom of nature… (Ibid. [4: 434–6])

FKE, like FULN and FHE, is supposed to express the supreme principle in a manner “closer to intuition (by means of a certain analogy) and thus nearer to feeling” (ibid. [4: 436]). In the Groundwork Kant suggests that for purposes of judgment we should rely primarily on FUL or FA (ibid. [4: 436–7]), but in The Metaphysics of Morals he appeals most often to the idea of humanity as an end in itself (FHE).

Interpretations vary but the basic analogy is with an ideal commonwealth in which all members legislate the laws and are subject to them. The members of a kingdom of ends are conceived, in abstraction from personal differences, as rational agents with private ends and as ends in themselves who autonomously legislate universal laws (ibid. [4: 433 ff.]). The “laws” here are ethical principles rather than enforceable state laws, and the lawmakers are not influenced by biases and irrationalities as state legislators often are. The analogy with the laws of a commonwealth suggests that the legislators do not legislate the supreme moral principle itself—the constitution, as it were, specifies the basic framework under which they make laws. Rather, they adopt more specific moral principles while being guided and constrained by ideas inherent in the supreme principle (autonomy, rationality, universality, and the dignity of legislators as ends in themselves). If this reading is correct, when Kant says without explicit qualification that we are subject only to laws we give ourselves (ibid. [4: 432]), then the “laws” here refer to the more specific universal ethical principles that we “legislate” with the authority, guidance, and constraints of the basic “law” of practical reason and morality (the Categorical Imperative). The basic law must be self-imposed in a different sense, for example by being authoritative for us because it is the fundamental principle of our own shared practical reason, not because of “alien causes,” natural sentiments, alleged intuitions, or even divine commands. Kant does not develop FKE further or propose examples to show how it might be applied to practical issues. Instead, his treatment of specific ethical principles in The Metaphysics of Morals mostly appeals to FHE. In addition, some passages suggest that members are conceived as making the laws, not together in a common legislative session (as the analogy suggests), but simply by always choosing in practice to act only on maxims that they can will as universal laws in the sense of FUL.

The most difficult and controversial aspects of Kant’s writings on ethics are his treatments of freedom of the will and how they figure in his defense of his claims about the Categorical Imperative. The main theses for which he argues in Groundwork I and II and the Critique of Practical Reason are: (1) he has identified the basic, comprehensive principle implicit in common moral thought, and it is expressed in FUL and equivalent formulas; and (2) common morality presupposes that this basic principle is the one and only Categorical Imperative in the strict sense. To be the Categorical Imperative in the strict sense a principle must be a universal and necessary principle of practical reason and not a particular hypothetical imperative or the general requirement of coherence among one’s ends and means (the Hypothetical Imperative). What Kant needs to show, then, is that common morality relies on the principle expressed in his formulas and that the principle is an unconditionally rational requirement. Kant argues analytically for the first claim in Groundwork I and II, trying step by step to reveal FUL as implicit in the ideas of a good will and duty. Passing over details, the main steps are these: Common morality accepts that only a good will could be good without qualification, or worth preserving in all situations. We express a good will when our (“morally worthy”) acts are both in accord with duty and done out of duty. So the essence of the basic principle of a good will is not that it must bring about desirable consequences, or even aim to do so, but that we must do what is morally required by maintaining an attitude of respect for the (moral/rational) law. By analyzing the essential motive or attitude of a good will, the argument is supposed to reveal that the basic principle of a good will is “Conform to universal law” and from this Kant infers FUL.

In Groundwork II Kant tries to draw out the presuppositions of the common idea of duty, and the mains steps can be paraphrased as follows. By contrast to what we ought to do for prudential or pragmatic reasons, a moral duty is what we ought to do for compelling reasons not based upon our personal aims and desire to be happy. We could have duties, understood this way, only if they are backed by a fundamental principle of reason that identifies these compelling reasons without appealing to prudence or rationally optional aims. In other words, duty must be based on a Categorical Imperative in the strict sense. From the concept of a Categorical Imperative, Kant argues, the only principle that could qualify is (to paraphrase): it is rationally necessary to conform to universal law. From this (again) Kant infers (with little explanation) that FUL is the Categorical Imperative.

These arguments, Kant dramatically points out, leave open the theoretical possibility that morality might be an illusion. They only reveal what common morality presupposes, not what is necessarily rational to accept. In Groundwork III Kant confronts this challenge, arguing that the presupposition that the supreme moral principle is unconditionally rational is valid for all purposes of deliberation and choice. As rational agents, Kant argues, we “cannot act except under the Idea of freedom” (2002 [4: 448]). This is an essential aspect of the standpoint of practice. In deliberation, choice, and acting for reasons we take our wills to be free in a negative sense—able to cause events “independently of alien causes determining it” (ibid. [4: 446]). Negative freedom, however, is inseparable from positive freedom or autonomy, “the property that a will has of being a law to itself” (ibid. [4: 447]). In order to make sense of the idea that we can act for reasons independently of our inclinations and sentiments, we must suppose that we can govern ourselves by standards inherent in our nature as rational agents. And, again assuming negative freedom, these rational standards must give us prescriptions that are not relative to our inclinations and sentiments. In sum, when we act as rational agents we necessarily take ourselves to have autonomy of the will, and Groundwork II is supposed to show that the Categorical Imperative is the standard of rational agents if they have autonomy of the will. The upshot is that in taking a practical standpoint we inevitably and rationally take ourselves to be subject to the Categorical Imperative.

In Kant’s view, freedom of will is an Idea that we must use in practical thinking but we cannot comprehend. Theoretical reason, empirical and speculative, can neither prove nor disprove that we have such freedom. Arguments in the Critique of Pure Reason are supposed to show that all empirical phenomena are subject to natural laws of cause and effect, but Kant held that the idea of free will presupposed by morality cannot be defined empirically or explained by natural laws. He embraced the apparent consequence, however obscure, that we must think of moral agents as “free” members of an “intelligible world” to which our spatial and temporal concepts do not apply. Perhaps few philosophers today follow Kant’s thinking this far, but his idea of autonomy has inspired some to develop and use related concepts.

Our moral choices are inevitably made in a context that includes a particular legal system and complex international relations. We can conceive of a “state of nature” but this remains a mere idea for most practical purposes. In Part I of The Metaphysics of Morals Kant presents his theory of law and justice, and earlier in Perpetual Peace (1795) he offers recommendations for international justice and global peace. Exactly how Kant’s moral theory is related to his theory of law and justice remains controversial, but some points seem clear. For example, Kant’s theory of law and justice is a part of his official (published) “metaphysics of morals,” and he held that it is an “indirect ethical duty” to obey the law. An exception, rarely mentioned, is that one should not do anything “intrinsically immoral” even if ordered to do so by the government in power. Law makes determinate rights of property, contracts, and status, and its officials have a juridical (and so indirectly ethical) duty to enforce the law justly. They must not, for example, use punishment simply as a means to promote general welfare. Thus even if the Categorical Imperative of the Groundwork is only meant as the appropriate standard for individual choices, and not for institutions, the requirements of law and justice are inevitably relevant to individual ethical decisions.

Law and justice, according to Kant, are concerned with the “external freedom” and enforceable rights of persons, not moral motivation. The “universal principle of right” (or justice) is a “postulate” similar in some respects to the universal law formula of the Categorical Imperative (FUL). This principle of right says: “Any action is right if it can coexist with everyone’s freedom in accordance with a universal law, or if on its maxim the freedom of choice of each can coexist with everyone’s freedom in accordance with a universal law” (Kant (1996a), [6: 231]). A corollary of the principle, Kant says, is that coercion to serve as a “hindering of a hindrance to freedom” is consistent with right (ibid.). He assumes a fundamental right to freedom, equality, and independence, and develops from this an account of “private law” which includes rights of property, contract, and status. Anyone in a state of nature, Kant argues, would have a duty to join and maintain a system of “public” law necessary for “a juridical condition.” This is not because of the brutality or inconveniences of a state of nature emphasized by Hobbes and Locke, but because “rightful” or just relations among persons are impossible without an authoritative way to settle disputes. Full justice, Kant argues, requires republican government with separation of powers, abolition of hereditary political privilege, and freedom to criticize the government. Full republican justice, however, is only a standard for gradual reform, for we must obey the law even in very imperfect (even “despotical”) legal systems. Scholars have argued, however, that “rogue states,” such as Nazi Germany, fail to meet even Kant’s minimum conditions for being a legitimate legal order that is owed obedience.

Regarding international justice Kant argues that, although a world government would be ideal in some respects, a voluntary federation of sovereign states would be the best hope for peace, at least in a world of diverse cultures and languages. States should recognize a cosmopolitan right of noncitizens to trade and visit peacefully, and they should not exploit indigenous peoples.

Ethics is concerned directly with the question “What ought I to do?” but Kant also addresses the question “What can I hope for?” This belongs primarily to his philosophy of religion, but it deserves mention here because his answer depends on his ethical theory.

Kant argues that knowledge of right and wrong is not based on religion, but to the contrary our moral knowledge provides the only basis for religious faith. In the Critique of Practical Reason Kant presents moral arguments for belief in God and immortality even though the Critique of Pure Reason established that we cannot strictly prove or even understand these “Ideas” beyond all possible experience. Religion cannot provide the basis for moral knowledge because in order to identify as morally authoritative any supernatural power or even any supposed exemplar of perfection (such as Jesus) we would already need to have an understanding of right and wrong. The moral arguments for faith are based on two prior moral ideas: that we must seek virtue independently of happiness and that the highest good (to be hoped for) would be perfect virtue combined with well-deserved happiness. In his late work Religion within the Boundaries of Mere Reason (1793), Kant argues that morality also provides the limits of a rationally acceptable religious faith. We should see moral duty as if commanded by God, but certain doctrines are ruled out as contrary to morality: for example, extreme doctrines of innate and incorrigible human depravity (as opposed to a willful propensity to evil), divine cruelty and partiality, and the efficacy of prayer for material rewards. The kingdom of ends discussed earlier has a Godlike “head” that has unlimited powers but, like a traditional political sovereign, is not subject to laws made by others. The head wills the same rational laws as the members do, however, and is not subject to the will of others just because it is independent and has no needs. The most basic principles for any rational being, human or divine, are essentially the same, although they become imperative for human beings who are finite and imperfectly rational.