Pious fraud (Latin: pia fraus) is used to describe fraud in religion or medicine. A pious fraud can be counterfeiting a miracle or falsely attributing a sacred text to a biblical figure due to the belief that the "end justifies the means", in this case the end of increasing faith by whatever means available.
Use of the phrase
The Oxford English Dictionary reports the phrase was first used in English in 1678. Edward Gibbon was particularly fond of the phrase, using it often in his monumental and controversial work The History of the Decline and Fall of the Roman Empire in which he criticized the likelihood of some of the martyrs and miracles of the early Christian church.
William W. Howells wrote that shamans know that their tricks are impostures, but that all who studied them agree that they really believe in their power to deal with spirits. According to Howells, their main purpose is an honest one and they believe that this justifies the means of hoodwinking his followers in minor technical matters.
Thomas Jefferson wrote to a doctor-friend in 1805:
One of the most successful physicians I have ever known, has assured me, that he used more bread pills, drops of coloured water, and powders of hickory ashes, than of all other medicines put together. It was certainly a pious fraud.