Kantian ethics

DOI: 10.4324/9780415249126-L042-2
Version: v2,  Published online: 2011
Retrieved July 23, 2024, from

1. Kant’s ethics

Kant’s main writing on ethics and politics can be found in Grundlegung zur Metaphysik der Sitten (Groundwork of the Metaphysics of Morals) (1785), Kritik der praktischen Vernunft (Critique of Practical Reason) (1788), Die Metaphysik der Sitten (The Metaphysics of Morals) (1797) and numerous sections of other works and free-standing essays. Throughout these writings he insists that we cannot derive ethical conclusions from metaphysical or theological knowledge of the good (which we lack) or from a claim that human happiness is the sole good (which we cannot establish). We lack the basis for a teleological or consequentialist account of ethical reasoning, which therefore cannot be simply a matter of means–ends reasoning towards some fixed and knowable good (see Consequentialism; Teleological ethics).

If Kant’s account of reasoning about action, and in particular moral reasoning, is not confined to means–end reasoning, what can it be grounded in? His alternative account proposes simply that moral principles must be principles for all rational agents at all times. He insists that we can have reason for recommending only those principles of action which could be adopted by all concerned, whatever their particular desires, social identities, roles or relationships. Correspondingly, practical reasoning about ethical matters must reject as fundamental any principles which cannot be principles for all concerned, which Kant characterizes as nonuniversalizable principles (see Universalism in ethics §5).

Kant gives this rather austere, modal conception of practical reason some grand names. He calls it the ‘supreme principle of morality’ and the ‘categorical imperative’. He formulates this fundamental principle of ethics in various ways. The formulation most discussed in the philosophical literature runs ‘act only according to that maxim [principle] through which you can at the same time will that it become a universal law’ or, alternatively, a ‘law of nature’ (1785: 421). The formulation that has had and still has the greatest cultural resonance requires us to treat others with impartial moral regard. It runs ‘use humanity, in your own person as well as in the person of any other, always at the same time as an end, never merely as a means.’ (1785: 429) (see Respect for persons §2). The equivalence of these formulations of the categorical imperative is far from obvious. One way of glimpsing why Kant thought they were equivalent is to note that if we treat others with equal regard, that is as persons rather than as things, then we must not destroy or impair their abilities to act, in order to leave it open to them to act on the same principles that we act on; hence we must act on universalizable principles. On a Kantian view, one of the worst features of consequentialist ethics is that it not merely permits but requires that persons be used merely as means or instruments if this will produce better results than other ways of acting.

Kant claims that the categorical imperative can be used to justify the principles underlying specific human duties (see Duty §2). For example, we can show by a reductio ad absurdum argument that a principle of false promising is not universalizable. Suppose that, as anyone does in consciously making a false promise, everyone were to adopt the principle of making false promises when in trouble: since the tendency to promise falsely would be universal, and known to be so, trust would be destroyed and nobody could get a false promise accepted, i.e. promising would turn out to be impossible, contrary to the hypothesis of universal adoption of the principle of promising falsely. There could then be no promises that were accepted by others, so no successful promising. A maxim of promising falsely is not universalizable, so the categorical imperative requires us to reject it. Parallel arguments can be used to show that principles such as those of stealing, unjust coercion or gratuitous or systematic violence are not universalizable, and so that it is a duty to reject these principles.

Kant calls duties such as these strict or perfect (namely, complete) duties. These are duties which can be observed by each towards all others. He also provides arguments to establish the principles of certain wide or imperfect (namely, incomplete) duties, such as those of helping others in need or developing one’s own talents. One way in which imperfect duties are unavoidably incomplete is that it is possible that they cannot be observed towards all others: in our world, nobody can help all those in need, or develop all possible talents. Kant calls these imperfect duties ‘duties of virtue’ (see Virtues and vices §§2–3).

The core of Kant’s ethics is his derivation of principles of duty from his conception of practical reason is, and provides the context for his discussion of many other themes. These include: the difference between the spirit and the letter of morality, i.e. between internalizing principles and merely conforming to them in outward respects (‘action from duty’ versus ‘action that conforms with duty’); the place of happiness in a completely good life; the need for judgment in moving from principle to act (see Moral Judgement §2); the justification of state power; and of a cosmopolitan account of justice (see Cosmopolitanism). Kant also develops the connections between his distinctive conceptions of practical reason and of freedom and his equally distinctive view of religion, which he sees as a matter not of knowledge but of reasoned hope for a future in which morality can be fully realized. In some works Kant articulates reasoned hope in religious terms; in others he articulates it in political and historical terms as a hope for a better this-worldly human future (see Hope §3). In any case, morality cannot be founded on religion, or on any other authority, tradition or revelation: rather religion must be founded on morality, which provides a full expression of practical reason in setting standards not only for action here and now but for our hopes for the future.

Since the Kantian moral law is not derived from an antecedent naturalist or metaphysical conception of the good, or from the values of society or divine commands, it can be seen as a matter of human agents freely adopting principles that express the autonomy of reason. Kant argues that only a law that is self-imposed can be universal and necessary in the way morality requires (1785: 439) (see Autonomy). The authority of any prescription imposed on the human will from the outside can be questioned, and some additional motivational factor would be needed to link the human will to it, which would (contrary to Kant’s central claims) make morality conditional.

Citing this article:
O'Neill, Onora and Jens Timmermann. Kant’s ethics. Kantian ethics, 2011, doi:10.4324/9780415249126-L042-2. Routledge Encyclopedia of Philosophy, Taylor and Francis,
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