Are You a Good Critical Thinker?

Source: C.M. Coolidge, A Friend in Need / Wikimedia Commons / Public Domain

The state of critical thinking today is no laughing matter—but let's start with some jokes anyway. They're bad, but they contain more than a grain of truth.

How is critical thinking like driving and sex? Everybody thinks they're really good at it. How do you identify bad thinkers? Just look at all those people who disagree with you about politics.

There's general agreement that there's a crisis in critical thinking today.¹ But there's no agreement about what critical thinking is. I will offer a proposal (based on Bishop & Trout 2005). And then I'm going to give you an unscientific critical thinking quiz—one I would have failed before I started doing research on this topic.

What is critical thinking?

Philosophers distinguish theoretical and practical reasoning. Theoretical reasoning is when you think about the way things are. Here, you reason well when you reason efficiently to true and useful beliefs. Practical reasoning is when you think about what to do. Here, you reason well when you reason efficiently to effective actions.

There's a lot more to say about what counts as efficient reasoning, useful truths, and effective action. That's why we philosophers write books about this stuff. But if we stick to common sense, we end up with a simple philosophy:

A good critical thinker reasons efficiently to useful truths and effective actions.

This philosophy has a destructive, critical side as well as a constructive, positive side.

The destructive side: Some people identify critical thinking with a single habit, trait, or skill. We can criticize such views by showing that this habit, trait, or skill doesn't always help you efficiently reason to useful truths and effective actions. For example:

• "A critical thinker questions everything." It's unwise to try to question everything—except as a philosophical exercise or as an effort to annoy people. A good critical thinker doesn't question everything. She asks the right questions—questions that lead to useful truths and effective actions.
• "A critical thinker always reflects on problems." It's impossible to reflect on every problem you face. And it's unwise to try. ("Should I get out of the way of the speeding truck? Hmmm.") A good critical thinker uses reflection wisely—to help her arrive at (you guessed it) useful truths and effective actions.

The constructive side: To become a better critical thinker, we need to identify and implement good reasoning strategies—ways of thinking that efficiently yield useful truths and effective actions. Needless to say, this is a massive undertaking.

An unscientific test of your critical thinking skills

Decades of research in psychology show that good critical thinking seldom comes naturally. It takes effort. But effort isn't enough. As my soccer coach was fond of saying, "Practice doesn't make perfect. Practice makes permanent. Perfect practice makes perfect." But too many of us don't think we need to improve our critical thinking skills.

Here's an unscientific test of your critical thinking skills. My answers—which I came up with only as a result of studying critical thinking—are in the footnotes. See if you come up with the same answers, and then judge the answers for yourself.

1. Five percent of people in your age and health cohort have disease D. Your doctor gives you a test for D that's 80 percent accurate, and you test positive for D. What are the chances you have D? (To say the test is 80 percent accurate is to say that if you have D, 80 percent of the time the test will say you have D and 20 percent of the time it'll say you don't; and if you don't have D, 80 percent of the time the test will say you don't have D and 20 percent of the time it'll say you do.)²
2. On January 1, the HIV rate in Palookaville was 1/10,000. On that day, in response to the HIV rate, the city elders implement a needle-exchange program (where drug addicts can exchange used needles for new needles). A year later, thousands of needles have been exchanged. But the HIV rate is up to 1.2/10,000. The city elders call you in as a consultant to evaluate the effectiveness of this program. What do you say?³

These aren't just idle brainteasers. It's important for us to be able to reason well about diagnostic problems ("Given a positive test for cancer or drug use, what are the chances a person has cancer or uses drugs?") and policy questions ("How well is a social policy working?").

An optimistic conclusion

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Despite all the doom and gloom surrounding critical thinking, I think psychological literature offers a hopeful picture. For many of the practically important problems we face, a good rule for solving those problems is already in our heads. Often, to become better critical thinkers, we don't need to learn a new rule; we just need to use the good rules we already know.