The Costume Error

A costume error is a forecast that got a future function or need right, then dressed it in a technology of the forecaster's own day that never arrived. The term is this site's own, and it is one of four grades on the Old Forecasts pages, next to hit, miss and untestable.

This site's standard example is Jules Verne's Moon shot. Three men did go around the Moon in December 1968, so the need was met. They did not leave from the 900-foot cannon Verne specified.

Limits of the term

Grading asks about the function first and the form second. If both the function and the implementation arrived, the grade is hit, even when the old wording uses the technical words of its time. An item with no source gets no grade.

The term describes one prediction at a time. It is not a historical law and says nothing about how often forecasts fail this way. See How We Rate a Reading.