The shape of ignorance

No system of complexity is free from error, the rational response is to build systems that know the shape of their own ignorance. That can say, in effect, “I do not know how to proceed here” and stop.

It follows that the design of an error message is not a peripheral matter to be left to whoever is free on a Friday afternoon, but a question with real commercial weight, since it is the point at which the machine either earns the user’s trust or spends it. To tell a user “an error has occurred” conveys little. It would be more honest, and more useful, to perhaps show what was attempted, what went wrong, and what remains open to the user, which is, after all, the same courtesy one would wish to be extended to in a foreign city, lost, and asking directions of a man who speaks a different tongue.

Underneath the technical question sits a simple reflection: gracefully handling failure may be a problem of humility on the part of the builders. It requires us to imagine, in some detail and without flattering ourselves, the many ways in which we could have been wrong, and to prepare a dignified reception for that eventuality.