The percentage of people who believe in evolution for valid scientific reasons is vanishingly small. A lot of intelligent-design type arguments against evolution are basically sound arguments that just happen to be wrong due to the mindboggling fact that the earth has been in existence for billions of years, which is nuts.
Evolution is even a bad example, because the theory itself is basically plausible. Think about what well-informed people believe about cosmology, which is broadly speaking this:
- The universe is extremely old (OK!)
- The universe didn’t always exist, and it started out smaller than a single atom. (Wait, what?)
- Virtually instantaneously (i.e., expansion time: human lifespan << human lifespan : total age of the universe), the universe expanded to something close to its current size due to something called an inflation field (Don’t ask what an inflation field is, because no one has any idea)
- After that, the universe evolved according to the normal physical laws we see on earth, although the scales are very different. (Whew, glad that weird shit is behind us)
- Except also, the only kind of matter we have any direct experience of is basically insignificant, and a solid majority of the stuff in the universe is invisible fairy dust that no one has ever seen or has convincingly explained the nature of. (…)
- Also, there is a mysterious energy that permeates the universe that makes gravity work backwards for no known reason. (You’re the guys who say that flat-earth makes no sense?)
Again, I’m not saying that fairy-dust theory is false, it’s apparently true (or true-ish, or a stand-in for the truth). The point is that virtually everyone who believes this crazy shit doesn’t believe it for well-justified empirical reasons. The explanation for inflation has to do with a mathematical property called “anisotropy” that can be sussed out only through an exhaustingly precise examination of the static you see when you tune an old-fashioned radio or television to a dead channel. (<-- This is precisely true!)
What actually happens is that people’s empirical beliefs are obtained, in almost all cases, by ingesting the pronouncements of authoritative figures. There are many excellent reasons why science guys are a much better source to obtain scientific beliefs from than the Pope, but it’s a serious error to assume that a person’s choice of epistemic authority figure tells you much about that person’s character. For the most part, people just follow the authority figures that their social context tells them to follow. The only people you can really get some information about is people who were born into one social context but chose to adopt the epistemology of another–people who deconverted from a serious religious sect (not Episcopalianism) or joined a cult.
Flat-earthers are remarkable not because their beliefs are weird (the earth does look flat!), but because they are unsanctioned. The strangeness isn’t what they believe, it’s that they came to believe something that is unsanctioned by all elements of society.