How to Live · ages 8–12
Is breaking a promise always wrong?
You promised to go. Something better came up. What do you actually owe?
A promise is a strange object. Nothing physical happens when you make one. No money changes hands, nothing is signed. And yet the whole machinery of ordinary life — being picked up, deadlines, friendships, aeroplanes — runs on them.
Hume noticed this and asked what a promise actually is. His answer: an invention. Two people need to be able to rely on each other in advance, so they create a convention, and the convention obliges you because it is useful to everyone including you. That makes it fragile in a specific way. Its power depends on it being kept often enough to be worth trusting, so each broken promise costs a little of everybody’s ability to plan.
Kant took the harder line. If you broke a promise whenever it suited you, promising would collapse, so the act is wrong regardless of consequences and regardless of whether anyone finds out. His illustration in the Groundwork is precisely a promise, which is a sign he thought it was the clearest test case there is.
The piece that is easiest to leave out is what a promise does to the other person. They rearranged something on the strength of your word — they saved the afternoon, they turned someone else down, they stopped worrying. Breaking it does not merely disappoint them, it takes back a plan they had already built on. That is why the small broken promise feels bigger to the person waiting than to the person who broke it.
Try it
Count the promises you made in the last week — including the ones nobody noticed. Then count how many you kept. Most people are surprised by the first number, not the second.
What do you think?
Do you think there is a right answer to this question?
Talk about it
- Does a promise to one person ever matter more than a promise to another?
- If someone breaks a promise to you, does that release you from yours?
- What makes a promise binding — the words, or the other person relying on it?
Yes, but… — the arguments people actually make
I only broke a small promise. No harm done.
Small promises are the training ground. Someone who finds reasons to break the small ones has already built the habit they will need for the large ones.
If I can't keep it, better to be honest and cancel.
Cancelling is better than vanishing, yes. But notice what has already happened: the other person rearranged their life around your word, and that time is not coming back.
Promises are just words. Only results matter.
Then nothing anyone says can be relied on in advance, and every plan you make with another person becomes a guess.
What other philosophers think
- Immanuel KantArgued that breaking a promise cannot be made a rule for everyone, because if everyone did it promising would stop working — so it is wrong regardless of who is hurt.
- David HumeExplained promises as an invention: we need to rely on each other, so we invented a convention of keeping our word, and it obliges us because it is useful to everyone.
- ConfuciusPut good faith near the centre of a life: a person whose word cannot be trusted is not really available to anyone.
- Sissela BokAsked what a promise does to the person waiting: it changes what they can plan, which means breaking it takes something from them rather than merely disappointing them.
If you want to go further
- Groundwork of the Metaphysics of Morals — Immanuel Kant1785. The promise example is his central illustration of a duty with no exceptions.
- A Treatise of Human Nature — David HumeBook III, where promises become a human convention rather than a sacred act.
- Lying: Moral Choice in Public and Private Life — Sissela Bok1978. The clearest modern treatment of truth-telling and its limits.
Most of these were written for adults, which is why it is worth reading them with someone older.