What is Kant's categorical imperative?

A moral rule that commands unconditionally: act only on principles you could will to become universal laws for everyone. Unlike hypothetical imperatives ("if you want X, do Y"), it binds regardless of desire.

What is an example of the categorical imperative?

Lying fails it: if everyone lied when convenient, promises would lose all meaning, so the maxim cannot be universalised. Lying is therefore forbidden as a matter of duty, not consequence.

How is the categorical imperative different from utilitarianism?

Kant judges actions by the principle behind them, not their results. Utilitarianism judges by outcomes (greatest happiness). The categorical imperative can forbid an act even when it would produce more total good.

The Categorical Imperative

Kant's supreme moral rule: act only on a principle you could will everyone to follow, and treat people as ends, never merely as means.

Originated with Immanuel Kant

What it means

Kant distinguished hypothetical imperatives ("if you want X, do Y") from the categorical imperative, which commands unconditionally. Its first formulation — the Formula of Universal Law — asks whether the maxim of your action could become a universal law without contradiction. Lying fails the test: a world where everyone lied would destroy the trust that makes lying useful. Its second formulation — the Formula of Humanity — forbids treating any person as a mere tool. For Kant, morality is therefore a matter of reason and consistency, not consequences or sentiment, and it applies equally to every rational being.

How it applies

A test for the consistency of personal and business decisions
A foundation for human-rights and consent-based ethics
A counterweight to purely outcome-based (utilitarian) reasoning

The deeper point

Kant’s test isn’t "what if everyone did this?" as a prediction of consequences — it’s "could I even will it as a universal law without contradiction?" Lying fails not because it leads to bad outcomes but because universal lying destroys the very trust that makes a lie function.

Related ideas

The Allegory of the Cave

Frequently asked

What is Kant's categorical imperative?: A moral rule that commands unconditionally: act only on principles you could will to become universal laws for everyone. Unlike hypothetical imperatives ("if you want X, do Y"), it binds regardless of desire.
What is an example of the categorical imperative?: Lying fails it: if everyone lied when convenient, promises would lose all meaning, so the maxim cannot be universalised. Lying is therefore forbidden as a matter of duty, not consequence.
How is the categorical imperative different from utilitarianism?: Kant judges actions by the principle behind them, not their results. Utilitarianism judges by outcomes (greatest happiness). The categorical imperative can forbid an act even when it would produce more total good.

Summary based on Kant's Groundwork (public domain) and the Stanford Encyclopedia of Philosophy.