04 Deontology and Kantian Ethics
Learn how Kantian ethics grounds moral obligation in reason, tests maxims through universal principles, respects rational agency, and distinguishes duty-based motives from merely compliant actions.
Moral law and duty
Kantian ethics is a form of . It evaluates actions by their relation to moral principles and duties, rather than judging them solely by their results. Kant argues that morality rests on reason and applies unconditionally to rational agents.
The supreme principle is the : a command that binds regardless of what a person happens to want. A , by contrast, tells someone what to do if they have a particular goal. For example, if you want to catch a train, you should leave on time.
Testing maxims and duties
A is the subjective rule on which a person acts. One example is: “When I need money, I will make a promise I do not intend to keep, so I can get a loan.”
To assess a , ask whether you could rationally will it as a rule for everyone in relevantly similar circumstances. If everyone made insincere promises to obtain loans, promising would lose its credibility and the practice would be undermined. Kant argues that this therefore cannot consistently be universalized.
The universal-law test is not simply a forecast of whether universal adoption would produce good or bad outcomes. It asks whether the can be thought and willed as a universal principle. Kant distinguishes perfect duties, which are strict requirements, from imperfect duties, which leave discretion about how to fulfill them. Not making a deceptive promise is an example of a ; helping others or developing one’s abilities are examples of imperfect duties.
Respect for persons
Kant also expresses the as a requirement to treat humanity, in yourself and others, always as an . People may cooperate to achieve one another’s goals, which involves using one another as means in an ordinary sense. The moral prohibition is against treating someone merely as a tool—for example, by deceiving or coercing them in a way that bypasses their capacity to choose.
Respect for persons means recognizing their rational agency and taking their ends seriously. In a business agreement, both parties may help one another achieve their aims. If both understand and freely accept the terms, neither is necessarily being treated merely as a means. Concealing crucial terms to secure someone’s agreement undermines their ability to make an informed choice and raises a Kantian objection.
Motivation and moral worth
An action is in accordance with duty if it meets the requirement. It is from duty when the agent acts because they recognize the moral requirement and are motivated by respect for it.
A shopkeeper who charges a fair price only to protect a reputation acts in accordance with duty, but the motive is self-interest. A shopkeeper who charges fairly because it is the right thing to do acts from duty.
Kant’s distinction does not mean that kindness or other natural inclinations are bad. An action can be both enjoyable and morally required. The relevant question is what grounds the agent’s choice: Kant holds that for an action to have distinctively moral worth, the agent must act from duty, not merely happen to do what duty requires.
Applying Kantian ethics
Kantian ethics grounds moral obligation in rational, universal principles. Assess an action by considering its and whether it could be willed as a universal law, whether it respects each person as an end rather than merely as a means, and whether the agent does what duty requires because it is their duty.