What do large numbers prove?

In times past, every civilised person believed that the earth was flat, and that the sun orbited the earth. Everyone also believed illnesses were caused by evil spirits. Many civilisations thrived on a slave economy, and everyone believed this to be the rightful arrangement. Similarly, many civilisations believed men worked outside the home while women worked inside the home, and everyone believed this to be the rightful arrangement. But today, all these arrangements are believed by everyone to be false and wrongful.

These simple counterexamples illustrate the fallacy known as Argumentum ad Populum, or Appeal to the Gallery. Just because a great number of people believe something true / false or right / wrong, does not therefore make that thing true / false or right / wrong. Large numbers of support or opposition prove only the position's popularity or unpopularity.

Assertions of "true / false" and "right / wrong" require other grounds of support. Appeal to numbers of supporters or opposers (that is, supporters of the contradictory position) cannot do that job.

This past Saturday saw large numbers of people wearing pink or white, in support of and in opposition to a particular position. Let us be clear what the large numbers are able or not able to prove or disprove.

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