A few days ago I was in Staples buying some supplies for a new craft project, and the cashier inquired whether I had a Staples preferred customer card. When I answered in the negative, he asked if I wanted one. I declined. He persisted: “But our customers are so happy to be in our program! Millions of people can’t be wrong!” On the contrary, I replied; they very well could be wrong. I did end up joining the program because it’s free and might save me some money – but his reference to millions of happy customers had no bearing on my decision.
This logical fallacy is known as the appeal to popularity. It is one of the many irrelevant appeals that people use to back a particular point of view, and like the ad hominem argument from my previous post, it is very easy to explain: just because a view is held by many people does not make it correct. Yet, it is a very common argument. I often find it used in defense of religious beliefs, e.g. God must exist because most people believe he does. How could all those people be wrong? As appealing as that argument may be, it is not rational, logical, or based on facts. Over the thousands of years of human history, millions of people have shared countless incorrect beliefs. Physicians used to treat patients without washing their hands or their instruments, because what we now call the germ theory of disease hadn’t yet been formulated (thank you, Louis Pasteur and your predecessors). Instead, doctors believed that disease spread from what they called miasma, or bad air. They had no conception of microscopic organisms such as bacteria, or invisible particles of virus, or even tiny parasites. Millions of people, including the physicians responsible for treating them, believed in miasma… and they were all wrong.
None of this is to say that the opposite of the appeal to popularity is true; that is, that the truth is only known by a select few and the rest of the world is simply mislead or deluded. This kind of thinking is common amongst conspiracy theorists. Much of their certainty comes from the feeling that they have access to rare, special knowledge that others don’t know or won’t accept. They convince themselves that they have extra sharp powers of logic and perception because they accept things others won’t, even when the facts aren’t on their side. Conspiracy beliefs make the believer feel like they are part of a special, rarefied group of the truly knowledgeable, and may actually work against the appeal to popularity by saying that the more people believe something (e.g. that fluoridated water or childhood vaccines are safe) the less likely it is to actually be true. This means we have to beware not just the appeal to popularity itself, but how it is deployed. Be extremely wary of any argument that goes along the lines of “But that’s what they want you to believe!”
It is also important to remember that plenty of things that almost everybody in the world believes to be true are actually true; but they aren’t true because we all believe them to be true – they are true because they are facts. In other words, our belief in something, or lack thereof, is completely irrelevant to the truth value of what we believe in. And the number of people who believe in something – or don’t believe in something – is equally irrelevant to the truth value of a given argument.
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