The obligation to support a contention by presenting adequate evidence. The term is a translation of the Latin onus probandi and was used in English courts of law from the late sixteenth century on. Transferred to any situation in which there was an obligation to prove something, it became a cliché in the nineteenth century. Attorney-novelist Scott Turow used it as the title for a popular novel involving a suicide and lawsuit (1990).

Performance is the only valid test. This proverbial expression of quality control dates from about 1600, appearing in print in William Camden’s Remains Concerning Britain (1605). It has been repeated many times over the centuries, particularly by British writers (including George Bernard Shaw and W. Somerset Maugham), for whom pudding is more of a basic dish than it is to Americans (it originally meant a kind of sausage, and later any food inside a crust); the Economist entitled a survey of the advertising industry “Proof of the Pudding” (June 1990). The term, generally shortened to “proof of the pudding,” survives on this side of the Atlantic as well.