[14][4][9] It uses an appeal to the beliefs, tastes, or values of a group of people,[12] stating that because a certain opinion or attitude is held by a majority, or even everyone, it is therefore correct.
The philosopher Irving Copi defined argumentum ad populum differently from an appeal to popular opinion itself,[19] as an attempt to rouse the "emotions and enthusiasms of the multitude".
[19][20] Douglas N. Walton argues that appeals to popular opinion can be logically valid in some cases, such as in political dialogue within a democracy.
[21] In some circumstances, a person may argue that the fact that Y people believe X to be true implies that X is false.
The similar fallacy of chronological snobbery is not to be confused with the ad populum reversal.
That line of argument is based on a belief in historical progress and not—like the ad populum reversal is—on whether or not X and/or Y is currently popular.