Lesson · 4 min Steady
Promises and Their Cost
In one line A promise binds because others rely on it, and breaking one costs trust even when the reason is good.
When you promise, you create a reason that was not there before. Someone now relies on you, plans around you, and has given up other options. Kant held that a promise you make only while it suits you is not a promise at all, since it could not become a rule everyone follows.
Promises can be broken for serious reasons: an emergency, or a promise that turns out to require a wrong act. Even then, something is owed: an apology, an explanation and, where possible, repair. The other person still relied on you.
The practical rule is to promise carefully. Promise what you can keep on a bad day, say what you are not sure of, and treat a broken promise as a cost you must make up.
The moving day
Tam promises to help a friend move on Saturday. On Friday night his sister calls, stuck at an airport, and asks for a ride at dawn. He cannot do both.
He drives his sister, but first he calls his friend, apologizes and offers to come Sunday and pay for a mover for the morning. His friend grumbles and accepts. Tam breaks the promise for a serious reason and still pays for it.
Try this today Before making a promise this week, ask if you could still keep it on a bad day.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “Promises and Their Cost.” https://quest2reason.com/learn/lesson/promises-and-their-cost. Accessed 13 November 2026.
Sources
- Stanford Encyclopedia of Philosophy, “Promises” — Covers why promises bind and when they may be broken.
- Immanuel Kant, Fundamental Principles of the Metaphysic of Morals (1785), translated by T. K. Abbott — The false promise as the example of a maxim that cannot become a universal law.