devil's advocate, (to play)

play (the) devil's advocate

To argue against or attack an idea, argument, or proposition—even if one is in favor of it—for the sake of debate or to further examine its strength, validity, or details. Refers to the "Advocatus Diaboli," a person employed by the Catholic Church to argue against the canonization of a saint (and therefore help determine if that person is truly worthy of sainthood). I'm all for universal health care, but I'll play devil's advocate in asking how the government intends to fund such a massive undertaking. Tom is always playing devil's advocate in any given conversation because he loves picking apart other people's arguments.
See also: advocate, play
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

devil's advocate, (to play)

To take a position against something that many others support, either for the sake of argument or to examine its validity. The term is a translation of the Latin advocatus diaboli, an official appointed by the Roman Catholic Church to argue against a proposed canonization. By the 1700s it was extended to broader use. R. Buchanan used it in The Heir of Linne (1887), “Even the Socialist party regarded him as a devil’s advocate, and washed their hands of him.” More recently, David Baldacci had it in Hour Game (2004), “‘Didn’t you try your best to convince me he was innocent?’ . . . ‘Just playing devil’s advocate.’”
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
See also: