You know something is important when TED has an entire playlist devoted to it. “The Value of Skepticism” playlist includes talks on statistics, fake news, quack medicine, courtroom persuasion, and one other topic . . . I forget what it was. I haven’t watched all of these talks, but I’m willing to bet that, if the talks are any good, they’ll draw distinctions between kinds of skeptics. Some kinds help us and some hurt us, and we need to understand the differences.

In my video (not yet on TED’s playlist), I talk about four kinds of skepticism as I stroll around the University of Missouri campus with my wonderful daughter Julia. Jump straight to the video or read on for a more detailed and nuanced discussion.

TED suggests that skepticism is valuable. Is it? We sometimes think of skeptics as old sticks-in-the-mud. Doubting Thomases who stubbornly refuse to accept what we all know to be true. But I think those doubters play a crucial role in our community, and we all need to be skeptical (in the right way), now and then. Healthy skepticism keeps us from becoming too gullible, too credulous. Good skeptics harass the snake-oil salesmen; they encourage us to walk to conclusions instead of jumping.

Varieties of Skeptics

But there are bad skeptics, too. In this post, I try to identify the various kinds of skeptics and say a bit about them. Perhaps you’ll even find yourself in here! Hopefully you’ll walk away with a clearer sense of what good skepticism is, why it is valuable, and how to practice it.

I think at least four varieties of skepticism exist, and these particular kinds come mainly from a mix of my own observation and reading. I’ll call them: philosophical, cynical, healthy, and silly skepticism. (In the video I use more or less the same terms, excepting the change to ‘silly’.) I’ll give a brief survey of each kind below. Let’s start with a well-known tour guide, René Descartes.

The Philosophical Skeptic

Descartes, of the “I think, therefore I am” fame, engaged in what I call philosophical skepticism. This is mostly an academic exercise designed to survey our beliefs and see which ones to keep and which to throw out. It may or may not involve actual, psychological doubt. When Descartes wondered whether the external world was real or an illusion, I don’t think he was actually worried about this. He wanted to improve his own stock of beliefs by thoroughly scrutinizing them through a method of doubt.

This sort of skepticism helps us in the same way that a home inspector or a mechanic doing a car inspection does. It identifies problem areas and faulty beliefs that need repair or replacement. I engage in this deep epistemic cleaning occasionally, but like home or car inspections, it is far too time consuming and “expensive” to carry out every day.

The Cynic: The Dark Side of Skepticism

What can we say about the (epistemic) cynic? The cynical or radical skeptic, frustrated by so many epistemic struggles and failures, throws in the towel on the pursuit of knowledge and concludes that we can’t know anything. This move, while unfortunate, is not self-refuting. The cynic can maintain that she believes all kinds of things, including the radical skeptical hypothesis itself. She believes it, but doesn’t claim to know it. (Mere belief is a more elemental and humble state.)

The cynical skeptic probably experiences real psychological doubt about her stock of beliefs. And since she can’t find any way out of the labyrinth, she succumbs to the Minotaur of radical skepticism. Now, I don’t want to give the cynic too bad of a rap here. Even Socrates himself claimed not to know anything, except that he didn’t know anything. But I think this was more the result of intellectual humility than epistemic despair. There are philosophers today who think the whole knowledge project is fraught with insurmountable problems and thus adhere to a kind of radical skepticism. But in my own view, I think they go too far.

The Silly Skeptic

The third kind of skeptic–the silly skeptic– uses doubt as a way of avoiding conflict or uncomfortable conclusions. They quickly appeal to skepticism and the limits of knowledge the minute someone raises a claim that they don’t like. People do this with religion, morality, politics–anything that makes them uncomfortable. It’s a great conversation stopper. The whole “fact/opinion” distinction found in public school curricula is a great example. Any claim or question (including the moral claim, “rape is wrong”) that we can’t answer with empirical proof is relegated to the skeptical, relativistic realm of “opinion.”

The silly skeptic uses the skeptical hypotheses irresponsibly. He isn’t interested in truth so much as he wants to protect his own cherished beliefs. Most times he doesn’t even understand the skeptical hypothesis he wields. He generalizes to everyone his own inability to sort through a difficult epistemic problem, as if any question that feels to hard for him must be impossible for all. Avoid this sort of pseudo-intellectual dodgery.

Another unfortunate example of irresponsible skepticism arises in some people’s response to science. Skepticism about the benefits and safety of vaccines and other traditional medicine, skepticism about the moon landing or about other scientific claims–all these are based, not on counter-evidence, but on fear and tribalist thinking. There’s nothing wrong with some healthy skepticism about science, but it must be based on better science or stronger evidence, not on conspiracy theories.

The Healthy Skeptic: the Path of Wisdom

Finally, the healthy skeptic uses the skeptical stance as a ship captain uses his spy glass. It is a tool that enables her to confirm her initial hypothesis that the spot on the horizon is another ship. The healthy skeptic dons her skeptical spectacles to look more closely at an object, to see more detail and increase accuracy of perception. She treads slowly, looking before leaping.

But the healthy skeptic doesn’t just whip out the doubt-guns at every opportunity, and she doesn’t blow up difficult conversations with the skeptical grenade. She exercises the classical virtue of prudence or wisdom, knowing the right time to look under the hood and kick the tires. Skepticism is a tool to be used in the pursuit of truth, not of personal comfort or “winning.”

The healthy skeptic also turns the critical eye on herself and her own beliefs, when appropriate. This demonstrates intellectual humility. If more people, including scientists, religious leaders, and politicians, adopted this attitude, what a difference it would make in the public perception of those offices. Part of the reason that so many have adopted a cynical or silly skeptic mindset toward these institutions is because of the failures and refusals to admit error! Believe, and admit, that you may be wrong! One psychologist, in trying to foster this kind of humility, is creating a published space for scientists to admit their mistakes.

So What?

I’ve described four kinds of skeptics: philosophical, cynical, silly, and healthy. In our own pursuit of knowledge, we should emulate two of them and reject the others. Here are some parting suggestions:

• There may be times when you feel cynical, but resist the pull to the dark side of skepticism!
• If you seldom or never take the skeptical stance, learn to stop, doubt and ask hard questions.
• Read s l o w l y and reserve judgment until you can check what the critics have to say.
• Skeptical thinking challenges us, but don’t shy away from it. Embrace it.
• Instead of being annoyed by them, learn from the skeptics around you.
• Don’t be afraid to be wrong and change your view.

I don’t take the hard-nosed stance of W. K. Clifford, but every adult who wants to believe responsibly must learn the skills of healthy skepticism. And if you’re following me so far, that includes this very post! Don’t assume that I have accurately assayed skepticism–do your own research!