Categorical imperative

Kant's supreme moral principle: a command that binds every rational agent unconditionally, whatever their desires.

Also: CI, formula of universal law, formula of humanity, Kantian ethics

What it means

Immanuel Kant contrasted hypothetical imperatives, which apply only if you want some end ('do not steal if you want to be popular'), with the categorical imperative, which applies regardless of what you want. His best-known formulations are to act only on a principle you could will as a universal law, and to treat humanity, in yourself and others, never merely as a means but always also as an end. A standard example is the lying promise: if everyone made promises they meant to break, nobody would trust promises, so the policy defeats itself. Critics question whether the formulations are equivalent, and whether acting from duty alone undervalues love and sympathy.

The questions it belongs to

• 3.2.2 Duty-Based ApproachesAre some things wrong even when they would do good?

Thinkers

• Immanuel Kant
• John Stuart Mill

Traditions

• Modern European

To read

• A System of Logic — John Stuart Mill
• An Answer to the Question: What Is Enlightenment? — Immanuel Kant
• Considerations on Representative Government — John Stuart Mill

Sources and further reading

• Kant’s Moral Philosophy (Stanford Encyclopedia of Philosophy)
• Categorical imperative (Britannica)

Written by the Coordinates of Thought editors and checked against the sources above on 29 October 2026. Not peer-reviewed. How we write and check.

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