
Universalization
Ask whether the rule behind the promise can coexist with everyone following that same rule.
Would promising remain possible if deception were the shared rule?
Understand this lens
Understanding the topic
Kantian universalization tests the maxim behind an action: the situation, action, and end that express the agent’s reason. One asks whether that maxim could be conceived and willed as a universal law. The test concerns rational consistency and willing, rather than a forecast that everyone will copy the behavior.
A maxim should describe the agent’s reason, including the relevant circumstance, proposed action, and end. Describing it as an arbitrary exception for one named individual avoids the moral issue rather than answering it. The universal-law test then asks about general authorization of that principle. The argument differs from predicting how many people would copy the behavior: it examines the coherence of a practice and of rational willing under the proposed rule.
Explore the example and debate
An illustrative example
Imagine seeking a loan by promising repayment while intending never to repay. State the maxim honestly, then imagine its general authorization. The promise depends on a practice of trust that the proposed principle places under pressure.
Where the debate stands
A maxim described too narrowly can appear to license nearly anything, while a vague one can distort the agent’s actual reason. Interpreters disagree about how to formulate and apply the test. Explaining why a principle fails matters more than offering the slogan “What if everyone did that?” without specifying the reasoning.
Take an invented rule allowing anyone to obtain assistance through a promise they never intend to keep. The rule relies on promises being trusted while authorizing conduct that undermines that trust. Explain the contradiction you think this generates before reaching a verdict. Next compare a truthful warning that repayment is uncertain. The recipient can now decide on informed terms, helping show why a deceptive maxim differs from a genuine commitment made under ordinary risk.



