A false belief is one which, in suitable circumstances, will cause the person entertaining it to experience surprise, while a true belief will not have this effect.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“This failure of adjustment constituted error, and one may say that you were entertaining a false belief. The test of error in the above illustration is surprise. I think this is true generally of beliefs that can be tested. A false belief is one which, in suitable circumstances, will cause the person entertaining it to experience surprise, while a true belief will not have this effect. But although surprise is a good criterion when it is applicable, it does not give the meaning of the words “true” and “false,” and is not always applicable. Suppose you are walking in a thunderstorm, and you say to yourself,” source