If the Bus Has Always Been on Time, Why Not Tomorrow?

If the bus you take has always arrived on time, planning around its usual arrival tomorrow is reasonable. But “it has been punctual before” does not logically guarantee “it will be punctual tomorrow”. Moving from what we have observed to what we have not yet observed is induction. Hume’s question was not whether we make that move, but what could justify it.

His argument presents two difficulties. Deduction cannot do the job: a late bus tomorrow would not be a contradiction, so tomorrow’s punctuality cannot follow necessarily from the past record. Saying “experience shows that induction usually works” uses past experience to establish that past experience predicts the future; the argument circles back on itself. Hume explained our natural expectation through habit, which is not a deductive guarantee. Later philosophers have offered different responses, and the dispute has not been settled by a simple formula.

My view is that doubting a guarantee need not mean discarding experience. We can still consult the bus’s record while allowing for weather, service changes and delays. A sound plan is a judgement open to revision, not a promise about tomorrow. Induction differs from a guess because it is grounded in observation; it differs from deductive proof because an unobserved tomorrow can still depart from the pattern.

https://plato.stanford.edu/entries/induction-problem/