Can a moral rule bind everyone?

A promise made to get the money

Imagine that Ingrid needs money to repair the bicycle she rides to work. A neighbor will lend it if she promises to repay him on Friday. She knows she cannot repay him by then, and she considers promising anyway: she wants the loan and has no intention of keeping the promise.

She might ask whether he will discover the deception, or whether losing his trust will cost her more than the repair. Kant asks a different question: what principle would she be acting on, and could she accept that principle as a law for everyone? The scene builds on his own false-promise example, from the second section of the Groundwork of the Metaphysics of Morals. [1]

Find the rule in the action

A maxim is the principle on which someone acts: how they propose to act, in certain circumstances, for a purpose. Ingrid’s maxim might be: “When I need money and can get it only by promising repayment, I will promise despite knowing I cannot pay on the agreed date, in order to obtain the loan.”

“Borrow money” would leave out exactly what is under examination: the deception, and the purpose it serves. Someone who borrows intending to repay acts on a different maxim, even if both borrowers say the same words. Kant distinguishes such a personal principle of action from a law that every rational being ought to follow. [1]

An ought that does not depend on a reward

A hypothetical imperative tells you what to do if you will a particular end. If Ingrid wants her neighbor to lend to her again, she should protect her reputation; if she stops caring about future loans, that reason loses its hold.

A categorical imperative claims authority whatever our aims. If deceiving someone is wrong, giving up the wish to be trusted cannot make it right. “Imperative” means a command of reason: we need to be told what we ought to do because our inclinations do not always carry us there. [1]

Kant therefore looks for a principle whose authority comes from reason, not from whatever a person happens to want. That does not make our needs and purposes unimportant. The question is whether they justify the means we choose.

Make the maxim universal

One formulation of the categorical imperative says, in paraphrase: act only on a maxim that you can also will to become a universal law. Kant illustrates it by asking us to picture our maxim as a law of nature, followed by everyone in the relevant circumstances. [1]

Apply it to Ingrid’s proposal. Suppose that everyone who needed a loan and knew they could not repay it made a false promise to obtain one, and that this was an established rule people could reckon with, not an occasional deception hidden among reliable promises. What would happen to the assurance on which her plan depends?

Kant argues that such promises would no longer assure a lender of repayment. Ingrid needs her neighbor to take her word, yet her rule, once universal, would destroy the basis for taking such words seriously. She is relying on a practice that her proposed law would make unavailable: the plan defeats its own necessary means. [1]

The argument does not predict that her single lie will ruin all trust, and it does not calculate whether this repair produces more happiness than harm. The test asks whether she can consistently will the principle she relies on to hold universally. Wanting everyone else to stay reliable while she makes an exception of herself does not meet it.

Giving yourself a law

Autonomy, for Kant, is the will’s giving itself a universal law. The word can sound like permission to choose any rule one likes, but Ingrid cannot make deception right merely by announcing that it is her personal policy. The law must be one she can rationally give to all, herself included, and her private advantage cannot make her an exception. [1]

Suppose she decides not to deceive. If she refuses only because she fears for her reputation, her decision depends on an expected benefit. If she refuses because she recognizes a rational requirement that applies to everyone, Kant locates its authority in reason itself, and she can acknowledge that authority while still wanting the money. Autonomy does not require her to have no desires; it concerns what governs her choice.

Such a law is neither a vote nor a report of what people already do: for Kant, a moral law can bind someone who dislikes it or breaks it. Whether reason can establish that authority is a further question. Section II describes what a categorical moral principle would require and leaves its full justification for further argument.

How much can this test decide?

Interpreters disagree about how far the test reaches. Robert Johnson and Adam Cureton present a procedure for assessing maxims: ask whether the universal rule is conceivable, and whether it can rationally be willed. [2] Allen Wood rejects treating universalization as a general procedure for moral decisions, arguing that it can both exclude acceptable maxims and admit objectionable ones. [3]

Wood’s examples include a policy of donating more than the average donor. Not everyone can exceed the average, yet that hardly makes greater generosity wrong. In the other direction, adding a particular person’s name and a rare occasion to a deceptive maxim may help it slip past a crude test without making the action any better. [3]

The challenge is substantial. We need an account of which details belong in a maxim, and of why failing the test amounts to a moral fault. The false-promise case gives us a clear argument to examine; it does not hand us an automatic answer to every difficult choice. Kant also offers other formulations of the categorical imperative, and how they relate to this one requires argument too.

Try the distinction

Suppose Ingrid objects, “My maxim is simply to obtain a working bicycle. And since autonomy means giving myself a law, I can approve that law for myself.” Explain what her description leaves out, and why her appeal to autonomy does not settle the case. This exercise is optional.

Read a possible response

Her description leaves out the means. Ingrid names her goal but omits how she intends to reach it, and the relevant maxim includes obtaining the loan through a promise she knows she cannot keep. Universalized, that principle would undermine the very assurance she relies on. Calling the rule her own does not solve the problem, because Kantian autonomy requires a law she can rationally will for everyone, not a permission based on her preference. The test questions this means of getting a bicycle. It does not condemn her need, decide every possible way of meeting it, or remove the interpretive difficulties about formulating and testing maxims.

Carry this forward

Kant joins freedom to a demanding form of responsibility: the reason you offer for your action must survive consideration as a law for everyone. Can freedom have a history? asks how freedom might also depend on recognition and social institutions.

Sources and limits

[1] Immanuel Kant, Fundamental Principles of the Metaphysic of Morals, the Groundwork (1785), translated by Thomas Kingsmill Abbott, Project Gutenberg eBook 5682, for maxims, the categorical imperative and autonomy. Read, in Section II:

• The universal law and its examples: the passage beginning “Everything in nature works according to laws” through the paragraph beginning “If now we attend to ourselves,” including the maxim note and four examples.
• Universal legislation: the discussion from “This principle, that humanity” through “Looking back now”.
• Autonomy and heteronomy: the subsections on each.
• The argument still required: Section II’s closing paragraph.

The transcription’s precise print edition was not established. The whole book was not read, and the German text and page images were not compared.

[2] Robert Johnson and Adam Cureton, “Kant’s Moral Philosophy”, Stanford Encyclopedia of Philosophy, substantive revision 2 October 2025, for the test as a procedure for assessing maxims. Read the complete §5, “The Formula of the Universal Law of Nature.” Its cited books were not separately consulted.

[3] Allen W. Wood, “The Supreme Principle of Morality”, Stanford-hosted author PDF, for the objections to universalization as a decision procedure: numbered pp. 1–7, §1, and note 2 on p. 42. This version is undated, and a print edition was not verified. Only those selections were read.

Sources accessed 18 September 2026. Ingrid’s bicycle and her objection are original teaching extensions of Kant’s loan case; the generosity and over-specific maxim objections are paraphrased from Wood. The lesson examines one formulation of the categorical imperative and a bounded disagreement about it, without claiming that all the formulations are obviously equivalent. No independent scholarly review or learner testing is claimed.