Ethics · Immanuel Kant, Groundwork of the Metaphysics of Morals, 1785
Kant’s universal law
What if everyone did what you’re about to do?
Kant offered a test for any action: imagine it as a rule everyone follows. If the rule would collapse, the action is wrong. Simple to state, surprisingly hard to live by.
1The puzzle
Kant’s test is a thought experiment you can run on any action: turn it into a rule for everyone. Pick a small, everyday act and scale it up from just you to the whole world. Watch what happens to the thing it relies on.
Scale three actions all the way up to everyone.
2Take a stand
Is it ever right to lie?
There’s no right answer here. Pick the one closest to what you actually think. We’ll test it next.
3The push-back
A few situations designed to test your answer. After each one, you can hold your ground or shift. Watch where you end up.
4The map of answers
You’re not the first to wrestle with this. Tap a thinker to see their answer and the strongest case for it. Open at least two.
5Turn it on yourself
You don’t need to be a Kantian to use his test. “What if everyone did this?” catches a lot of small exceptions we quietly make for ourselves.
Your answers stay in this browser. Nobody else sees them.
6Your question card
Kant’s universal law
What if everyone did what you’re about to do?
Before you act, imagine your action as a rule for everyone. If the rule would collapse or you couldn’t accept it, think again.
The main answers
John Stuart Mill: Actions are right as they tend to promote happiness, wrong as they tend to produce the reverse.
Benjamin Constant: You owe the truth only to those who have a right to it. The murderer has none.
Aristotle: Be the kind of person who is honest, and use practical wisdom to know what honesty requires here.
W. D. Ross: We have several real duties, such as honesty, keeping promises and not harming. When they clash, we judge which is stronger.
Christine Korsgaard: A Kantian can lie to the murderer, because his lie to you already breaks the conditions of honest exchange.
Immanuel Kant: Act only on rules you could will everyone to follow. Never treat people merely as means.
Where you stand
Your note
Notice this week
Notice one moment this week when you make an exception for yourself. Ask: what if everyone did this?