The Skeptic's Trilemma

by Scott Alexander5 min read15th Mar 200915 comments


Practice & Philosophy of ScienceHistoryEpistemology

Followup to: Talking Snakes: A Cautionary Tale

Related to: Explain, Worship, Ignore

Skepticism is like sex and pizza: when it's good, it's very very good, and when it's bad, it's still pretty good.

It really is hard to dislike skeptics. Whether or not their rational justifications are perfect, they are doing society a service by raising the social cost of holding false beliefs. But there is a failure mode for skepticism. It's the same as the failure mode for so many other things: it becomes a blue vs. green style tribe, demands support of all 'friendly' arguments, enters an affective death spiral, and collapses into a cult.

What does it look like when skepticism becomes a cult? Skeptics become more interested in supporting their "team" and insulting the "enemy" than in finding the truth or convincing others. They begin to think "If a assigning .001% probability to Atlantis and not accepting its existence without extraordinarily compelling evidence is good, then assigning 0% probability to Atlantis and refusing to even consider any evidence for its existence must be great!" They begin to deny any evidence that seems pro-Atlantis, and cast aspersions on the character of anyone who produces it. They become anti-Atlantis fanatics.

Wait a second. There is no lost continent of Atlantis. How do I know what a skeptic would do when confronted with evidence for it? For that matter, why do I care?

Way back in 2007, Eliezer described the rationalist equivalent of Abort, Retry, Fail: the trilemma of Explain, Worship, Ignore. Don't understand where rain comes from? You can try to explain it as part of the water cycle, although it might take a while. You can worship it as the sacred mystery of the rain god. Or you can ignore it and go on with your everyday life.

So someone tells you that Plato, normally a pretty smart guy, wrote a long account of a lost continent called Atlantis complete with a bunch of really specific geographic details that seem a bit excessive for a meaningless allegory. Plato claims to have gotten most of the details from a guy called Solon, legendary for his honesty, who got them from the Egyptians, who are known for their obsessive record-keeping. This seems interesting. But there's no evidence for a lost continent anywhere near the Atlantic Ocean, and geology tells us continents can't just go missing.

One option is to hit Worship. Between the Theosophists, Edgar Cayce, the Nazis, and a bunch of well-intentioned but crazy amateurs including a U.S. Congressman, we get a supercontinent with technology far beyond our wildest dreams, littered with glowing crystal pyramids and powered by the peaceful and eco-friendly mystical wisdom of the ancients, source of all modern civilization and destined to rise again to herald the dawning of the Age of Aquarius.

Or you could hit Ignore. I accuse the less pleasnt variety of skeptic of taking this option. Atlantis is stupid. Anyone who believes it is stupid. Plato was a dirty rotten liar. Any scientist who finds anomalous historical evidence suggesting a missing piece to the early history of the Mediterranean region is also a dirty rotten liar, motivated by crazy New Age beliefs, and should be fired. Anyone who talks about Atlantis is the Enemy, and anyone who denies Atlantis gains immediate access to our in-group and official Good Rational Scientific Person status.

Spyridon Marinatos, a Greek archaeologist who really deserves more fame than he received, was a man who hit Explain. The geography of Plato's Atlantis, a series of concentric circles of land and sea, had been derided as fanciful; Marinatos noted1 that it matched the geography of the Mediterranean island of Santorini quite closely. He also noted that Santorini had a big volcano right in the middle and seemed somehow linked to the Minoan civilization, a glorious race of seafarers who had mysteriously collapsed a thousand years before Plato. So he decided to go digging in Santorini. And he found...

...the lost city of Atlantis. Well, I'm making an assumption here. But the city he found was over four thousand years old, had a population of over ten thousand people at its peak, boasted three-story buildings and astounding works of art, and had hot and cold running water - an unheard-of convenience that it shared with the city in Plato's story. For the Early Bronze Age, that's darned impressive. And like Plato's Atlantis, it was destroyed in a single day. The volcano that loomed only a few miles from its center went off around 1600 BC, utterly burying it and destroying its associated civilization. No one knows what happened to the survivors, but the most popular theory is that some fled to Egypt2, with which the city had flourishing trade routes at its peak.

The Atlantis = Santorini equivalence is still controversial, and the point of this post isn't to advocate for it. But just look at the difference between Joe Q. Skeptic and Dr. Marinatos. Both were rightly skeptical of the crystal pyramid story erected by the Atlantis-worshippers. But Joe Q. Skeptic considered the whole issue a nuisance, or at best a way of proving his intellectual superiority over the believers. Dr. Marinatos saw an honest mystery, developed a theory that made testable predictions, then went out and started digging.

The fanatical skeptic, when confronted with some evidence for a seemingly paranormal claim, says "Wow, that's stupid." It's a soldier on the opposing side, and the only thing to be done with it is kill it as quickly as possible. The wise skeptic, when confronted with the same evidence, says "Hmmm, that's interesting."

Did people at Roswell discovered the debris of a strange craft made of seemingly otherworldly material lying in a field, only to be silenced by the government later? You can worship the mighty aliens who are cosmic bringers of peace. You can ignore it, because UFOs don't exist so the people are clearly lying. Or you can search for an explanation until you find that the government was conducting tests of Project Mogul in that very spot.

Do thousands of people claim that therapies with no scientific basis are working? You can worship alternative medicine as a natural and holistic alternative to stupid evil materialism. You can ignore all the evidence for their effectiveness. Or you can shut up and discover the placebo effect, explaining the lot of them in one fell swoop.

Does someone claim to see tiny people, perhaps elves, running around and doing elvish things? You can call them lares and worship them as household deities. You can ignore the person because he's an obvious crank. Or you can go to a neurologist, and he'll explain that the person's probably suffering from Charles Bonnet Syndrome.

All unexplained phenomena are real. That is, they're real unexplained phenomena. The explanation may be prosaic, like that people are gullible. Or it may be an entire four thousand year old lost city of astounding sophistication. But even "people are gullible" can be an interesting explanation if you're smart enough to make it one. There's a big difference between "people are gullible, so they believe in stupid things like religion, let's move on" and a complete list of the cognitive biases that make explanations involving agency and intention more attractive than naturalistic explanations to a naive human mind. A sufficiently intelligent thinker could probably reason from the mere existence of religion all the way back to the fundamentals of evolutionary psychology.

This I consider a specific application of a more general rationalist technique: not prematurely dismissing things that go against your worldview. There's a big difference between dismissing that whole Lost Continent of Atlantis story, and prematurely dismissing it. It's the difference between discovering an ancient city and resting smugly satisfied that you don't have to.



1: I may be unintentionally sexing up the story here. I read a book on Dr. Marinatos a few years ago, and I know he did make the Santorini-Atlantis connection, but I don't remember whether he made it before starting his excavation, or whether it only clicked during the dig (and the Internet is silent on the matter). If it was the latter, all of my moralizing about how wonderful it was that he made a testable prediction falls a bit flat. I should have used another example where I knew for sure, but this story was too perfect. Mea culpa.

2: I don't include it in the main article because it is highly controversial and you have to fudge some dates for it to really work out, but here is a Special Bonus Scientific Explanation of a Paranormal Claim: the eruption of this same supervolcano in 1600 BC caused the series of geologic and climatological catastrophes recorded in the Bible as the Ten Plagues of Egypt. However, I specify that I'm including this because it's fun to think about rather than because there's an especially large amount of evidence for it.