Lesson · 4 min Steady
Custom, the Guide of Life
In one line Past cases make a future case likely, not certain, so trust habit and stay ready for a surprise.
Hume asks why we expect tomorrow to resemble yesterday. The sun has risen every day we have seen, but nothing in that record proves it will rise again. No argument from reason alone closes the gap, because the argument would itself assume that the future resembles the past.
His answer is not to stop expecting. It is custom, the habit of mind that experience builds, which guides life far better than a demand for proof. A cook trusts the oven, a driver trusts the brake, and both are right to, though neither can prove it.
The lesson is about what kind of support we have. Habit is a sturdy guide and a fallible one. Count your expectations as well grounded in past cases, stay ready for the day a case breaks the pattern, and do not call a habit a proof.
Russell’s chicken
A chicken is fed every morning by the same farmer. Each day adds to its confidence that the farmer is a friend, and on the morning before a holiday the confidence is at its highest.
The chicken’s expectation was reasonable on the evidence it had, and it was still wrong. Custom guides us well until a case breaks the pattern, which is why it asks for readiness and not for certainty.
Try this today Pick one thing you expect without question, and name what you would do if it failed this time.
Cite or share this lesson
A plain reference you can paste into notes or an essay:
Quest2Reason. “Custom, the Guide of Life.” https://quest2reason.com/learn/lesson/custom-the-guide-of-life. Accessed 13 November 2026.
Sources
- David Hume, An Enquiry Concerning Human Understanding (1748), sections IV and V — The argument that past experience cannot prove the future, and the account of custom as the guide of life.
- Stanford Encyclopedia of Philosophy, “The Problem of Induction” — A modern account of Hume’s problem and the main replies.
- Bertrand Russell, The Problems of Philosophy (1912), chapter VI, “On Induction” — The chicken fed every day by the man who at last wrings its neck. Retold here, not quoted; the holiday is this lesson’s detail.