Studying Science Doesn’t Always Teach Critical Thinking

Not long ago, Jerry Seinfeld shared one of his secrets to developing great comedy. “It’s a very scientific thing to me,” he said. “You run the experiment, then the audience just dumps a bunch of data on you…. Then it’s back through the rewrite process.”

Seinfeld is not alone. In Think Again, I covered striking evidence that learning to think like a scientist improves your ability to learn. You start to see your opinions as tentative hypotheses waiting to be tested, and your decisions as experiments without a control group. You get faster at recognizing when you’re wrong and iterating to improve on your mistakes.

Since then, many readers have asked how to build their critical thinking muscles. For years, I assumed that the key step was to take more science classes. Then a pair of studies forced me to rethink that assumption.

In a study of undergraduates, researchers tracked how students progressed in statistical, methodological, and logical reasoning based on their academic majors. The most substantial gains in statistical and methodological reasoning were among social science majors, while the biggest spikes in logical reasoning were among math and humanities majors. Natural science majors generally made the least progress in all three types of reasoning.

When they turned to graduate students, the researchers found similar results. From their first to third year, psychology and medical students got better at statistical, methodological, and logical reasoning. Law students only improved in logical reasoning. And chemistry students showed no gains in any type of reasoning.

Why? A likely explanation is that chemistry is a deterministic science; students learn laws and rules about necessary and sufficient causes. Medicine and psychology are probabilistic sciences; they teach students to identify conditions under which causes may or may not operate.

Of course, we don’t know for sure that academic majors are actually influencing reasoning skills. It may be that students are self-selecting into particular fields based on their skills. There’s also the question of whether it’s not the natural sciences but dominant methods of teaching that limit students. It’s hard to imagine taking a course with Richard Feynman without learning to think scientifically. And economists have argued that even if certain disciplines are causing gains in reasoning skills, they’re not teaching general thinking skills—students are only improving in the specific reasoning skills they learn in class.

Still, that doesn’t undermine the notion that the social sciences and humanities are well-suited to teaching critical thinking. Controlled experiments have demonstrated that people become more flexible in their thinking when they’re introduced to stories and objects as conditionals rather than absolutes. And one of the key features of classrooms that promote critical thinking is exploring contingencies for when different conclusions hold.

It's tempting for me to suggest that if you want to be a better critical thinker, it’s worth studying psychology. But that would be self-serving. Let me instead say I wish more people took philosophy and anthropology.

Regardless of what you study, you can always take a page out of the Seinfeld playbook. I once had the chance to ask him how he generates his material. His answer: he spends a lot more time than the average person observing the strange little things humans do and testing out different explanations. He had just held the door for someone and noticed that as they walked through it, they still touched the door. Later, one of his hypotheses made it into his standup routine: “You don’t trust me to hold the door? This is a very insulting moment because I am going out of my way, as a stranger, to do this for you, and it doesn’t impress you at all.”