In our ongoing survey of red herrings, responses to arguments that don’t address the original issue, they’ve mostly taken Latin names starting with argumentum ad, translated as “argument from” or “argument to.” In practice, the argumentum is omitted: argumentum ad hominem, “argument from the person,” is usually just cited as ad hominem.
Argumentum ad populum
Elvis Presley’s ninth album is titled 50,000,000 Elvis Fans Can’t Be Wrong, but of course that’s a logical fallacy, with no disrespect intended to the King. The fallacy is known popularly as the “argument from common consent,” and more formally as argumentum ad populum. If the majority believes that proposition X is true, then it’s presumptively true.
On February 6-7, 2009, a few days before the 200th anniversary of the birth of Charles Darwin, (February 12, 1809), the Gallup organization conducted a national survey on the question, “Do you personally believe in the theory of evolution, do you not believe in evolution, or don’t you have an opinion either way?” The disappointing answer is hardly surprising to anyone who grew up in the American south. Approximately 39% of Americans believe; 25% do not believe—and 36% have no opinion either way. (The percentage of believers goes up with education—and down with church attendance or Republican party membership.)
Americans who believe in evolution are a minority, but what does that have to do with whether Darwinian evolution is a fact? Polls for or against a given factual proposition are common, but they’re logically meaningless. That is, of course, when the factual proposition under discussion is something other than opinion.
If the factual question is “Do most Americans believe in Darwinian evolution?” then, the factual answer can be determined by a poll. Otherwise, not.