Mind & body, Research, Science & environment

Amidst misinformation, critical thinking needs a 21st century upgrade

New book argues that scientific reasoning is a necessity for living in a world shaped by science and tech

Headshots of three men next to image of book cover
The three authors: Robert MacCoun of Stanford and John Campbell and Saul Perlmutter of UC Berkeley.

UC Berkeley

In 2013, the University of California, Berkeley, debuted a course to teach undergraduates the tricks used by scientists to make sense of the world, in the hope that these tricks would prove useful in assessing the claims and counterclaims that bombard us every day.

It was launched by three UC Berkeley professors — a physicist, a philosopher and a psychologist — in response to a world afloat in misinformation and disinformation, where politicians were making policy decisions based on ideas that, if not demonstrably wrong, were at least untested and uncertain.

The class, Sense and Sensibility and Science, was a hit and convinced the professors to write a book based on the class that provides tips not only on how to systematically wade through the noise around us to seek the truth, but also how to work with those holding different values to come to a consensus on how to act.

The book, Third Millennium Thinking: Creating sense in a world of nonsense (Little, Brown, Spark), will be published today, March 26 — just in time for the 2024 election season, which promises to be more bluff and bluster than rational argument.

cover of book - white background with title, authors' names and colorful interwoven wires
Third Millennium Thinking: Creating sense in a world of nonsense (Little, Brown, Spark).

Courtesy of Little, Brown, Spark

Saul Perlmutter, a Nobel Prize-winning professor of physics and Lawrence Berkeley National Laboratory scientist, had been discussing the need for an undergraduate course on critical thinking with philosophy professor John Campbell for nearly a year when they both agreed that they needed a third perspective — that of a social psychologist. They approached Robert MacCoun, then a UC Berkeley professor of public policy and law who is now at Stanford Law School, and he was all in.

The three authors will get together to discuss the book at the Commonwealth Club in San Francisco on Thursday, March 28.

The course, now co-taught with Amy Lerman, UC Berkeley professor of public policy and political science, currently enrolls 300 students for Zoom lectures and additional smaller, in-person discussion sections. Courses based on the UC Berkeley curriculum have been adopted at Harvard University and UC Irvine, and, this spring, by the University of Chicago. A high school course is currently being developed and classroom-tested as well. Berkeley News sat down with Perlmutter, Campbell and MacCoun to discuss the book and why the world needs a science-based approach to critical thinking and decision making.

Berkeley News: Why the need for such a course and your new book?

Saul Perlmutter: There was a period, back in 2012 or thereabouts, when we were watching our government at the time try to make rational decisions, and it just looked so unlike a lunch table conversation among a bunch of scientists. They weren’t using the same vocabulary, the same terms, the same approaches to a problem. At the time, I was thinking, “When did scientists learn this stuff?” I realized it wasn’t in any science course that I had ever taken. It just somehow seemed to be taught by osmosis, by going through research training. So I asked, “Is there any way that we could articulate what those concepts are that scientists were using and taking for granted at the lunch table, and try to teach it to everybody?” That was one of the starting points.

But you know, if you go to a physics faculty meeting, it doesn’t necessarily run much more rationally than any other faculty meeting. We had to bring in other expertise, and the obvious ones were social science and philosophy. Social psychology brought in the idea that when groups get together, they’re not thinking what they think they’re thinking — there are many known failings in individual and group thinking, and ways to do better. And then philosophy brought in all the questions of: How do we weigh different elements of decision-making against each other, topics like how to weave in the values, fears and goals that drive a decision? What is the role of experts in a democracy?”

Physicist Saul Perlmutter, social psychologist Robert MacCoun and philosopher John Campbell discuss their new book, Third Millennium Thinking: Creating sense in a world of nonsense (Little, Brown, Spark), and the popular UC Berkeley course that led to the book, which was published March 26, 2024. (Video credits: Brian Delahunty, Steven Zeng, Taylor Zhu and Jarvis Nguyen, UC Berkeley)

John Campbell: Saul just rung me out of the blue and said, “Do you want to talk about this?” What came into focus for me in our conversations was how much uncertainty people have about what the place is of science in our society. It often seems, to me anyway, to be regarded as a kind of magic — of course, they can do anything these days. They can put robots into your bloodstream and make you do what they like. The only question is what their motivations are, and what are they up to.

It seems to me that we all need to have more of a sense of what science can do, what its possibilities and limitations are. That scientists can’t just magic up anything, they have techniques we can use ourselves in everyday life.

Rob MacCoun: I was delighted when Saul described this course to me and said, “Would you be interested?” I said, “Absolutely.” I had been doing empirical work on a lot of really hot-button issues — gays in the military and drug legalization, being two of them — and had despaired over the amount of bias in the interpretation and use of research evidence.

Saul Perlmutter: After we had been talking a little bit, we put up a sign saying: Are you embarrassed watching our society make decisions? Come help invent a course, come help save the world. And about 30 students, mostly grad students and postdocs, came forward. We met every week for about nine months. We came up with 23 topics and exercises designed to teach these topics experientially in a way that people could remember them and use them whenever they came across the need, not just in their own field. Over the years, we’ve tried to get as many of those into the course as we could.

BN: In your book you have chapters on many of these topics: how not to confuse correlation with causation; thinking in terms of probability, not certainty; admitting and controlling for your biases; not being afraid to admit you’re wrong. You argue that these aren’t only useful in the sciences.

MacCoun: This is not a book that says, “Here are the most important findings in science.” It’s also not even about the scientific method, although we do teach some of that. It really is about things that are part of science culture that nobody talks about explicitly, habits that people just pick up. It’s not unique to the natural sciences. I think social scientists, partly through imitation, have also learned a lot of those things. That’s because science is a profession where you have to work with people who disagree with you about something, and you can’t just say, “OK, we agree to disagree.” You believe that there actually is an answer out there. And while both sides think they’re more likely to have the right one, they agree there is a right answer to be found. And both sides want to know how: Can we at least get closer to the right answer?

dozens of students standing and kneeling, all pointing to their left
One of the early Sense and Sensibility and Science classes. The originators of the class and the authors of the book are in the front row center: Robert MacCoun and Saul Perlmutter (kneeling) and John Campbell (seated).

Aditya Ranganathan, UC Berkeley

That original group was mostly from the sciences. We had this workshop for the first summer, just trying to imagine what such a class would look like, trying to come up with exercises. I have to say, that’s the most preparation I’ve ever put into any course I’ve ever taught. But it paid off because the first time we taught it, it was very well received by the students, and we felt like, “Oh, this is something distinctive.”

Saul Perlmutter: I remember at the time I was thinking that these were things that scientists seemed to know, but that most of society did not seem to know. And so maybe we should be teaching non-scientists the material. But then I realized, actually, scientists also need to learn it much younger. I should have learned it as an undergraduate or even as a high school student, not waiting until I learned it by osmosis in graduate school.

Campbell: There’s something about recognizing, as Rob says, that there’s an objective fact that we’re trying to get to. But the flip side of that is recognizing that, OK, we’re finite humans, maybe we can only get to the facts probabilistically. We can put weights on the objective facts, we can say this is far more likely than that, but you always have to accept the possibility of you being in error about those facts. If we could all recognize that however strong a hunch we have that this thing is right, there is always room for error, it would greatly facilitate debate across divides. At the same time, there is something out there, and it’s worth fighting about how we get it right.

MacCoun: If you’re trying to actually solve problems in the world, in the empirical world, science is the best game in town, and it’s got a proven track record. We want this book to be for the general public. We feel evangelical about it — why doesn’t everybody know about this stuff? We hope it will get readers.

BN: Is there something about the current time — the new century and the beginning of the third millennium — that makes this more important now?

Perlmutter: There’s a mix of things that are making this a particularly fertile time for this book. One is, there’s so much information out there that you can’t actually teach science anymore that’s intended to be comprehensive. Once upon a time, most educated people knew most of science, or at least what science was known at the time. But now I think it’s almost impossible. But what you can do is you can teach the elements that go into scientific thinking so that when you go to a YouTube video or read an article, you have some way of judging what’s being done and whether it’s being done in a way that meets these standards of thought.

3 men sitting in chairs around a small table, one of them gesticulating
Saul Perlmutter, Robert MacCoun and John Campbell discussing their new book, Third Millennium Thinking, which was published Mar. 26, 2024.

Steven Zeng and Brian Delahunty, UC Berkeley

Toward the end of the book, Rob and John, I think, captured well the sense in which the world has moved from being very authoritative, where a single person is the genius who makes some discovery, to a world now where there’s a much deeper understanding of how authority is a community process. In some sense, we’re ripe for this. So at the same time that some aspects of societal thinking have broken down lately, other aspects have advanced dramatically, and I think we’ve come to a much better place in understanding how people can figure things out together.

Campbell: Something else that wasn’t here 100 years ago is just the sheer volume of the ways that science is impacting everyday life. I mean, you can’t really do a book on decision-making that’s going to apply at all, really, to most decisions you make without having some sense of where science should be factoring into your decisions. There is practically nothing that is free of some scientific aspect or where science can’t be of some help in decision-making. But you really need a good sense of what the science is about, what its scope and limits are, where you might plug it in, and how it integrates with values.

Perlmutter: We’re not saying, “Give up on experts.” Look carefully at how the experts are presenting and choose your experts well. Choose them based on a self-critical willingness to change their mind and willingness to state things tentatively when necessary or strongly when needed.

Campbell: As humans, we crave certainty. It’s so appealing when politicians express themselves with full conviction about everything. One thing we should be looking for in politicians is that openness to the possibility of error. This is a perplexing and confusing world, and it is so agreeable and comforting when someone says, “I can lead you through all this.” We have to learn not to do that and to live with the bewilderment.

MacCoun: We try to convey a pair of attitudes that people usually don’t think of together. One is skepticism, as opposed to gullibility, and the importance of cultivating a sense of skepticism. But the other is optimism, as opposed to pessimism. I think Saul was the first person I ever heard say that, you know, most scientists assume that every problem does have a solution, that we will find a solution. We talk about skepticism as the brake pedal and optimism as the gas pedal. If you want to get somewhere, you need both pedals.

BN: I like that, in your book, you talk not only about how to make rational, fact-based decisions individually, but also how to work with other people to come to a consensus when not everyone shares the same values.

Perlmutter: The course could have just stopped with teaching you how to think rationally together. But we decided to incorporate rational thinking with all the other parts that go into a decision, like the values and the goals and the fears and the ambitions. If you don’t come up with some organized, principled way to incorporate all those things together with rationality, we know which parts are going to get lost. It’s not going to be the fears and the goals and the ambitions. It’s going to be the rationality. So if you care about the rationality, then we felt you had to care about what it looks like when you try to weave that together with the values and goals and fears.

three smiling men linking arms in celebration
The originators of the Sense and Sensibility and Science course after a successful class in 2014. Left to right, Robert MacCoun, Saul Perlmutter and John Campbell.

Aditya Ranganathan, UC Berkeley

Campbell: I think there’s something really awful about the way that we all in Anglo-American society think about values. We think, well, science tells you the objective facts, but science doesn’t tell you anything about values. Therefore, the values are all very subjective. Once we’ve agreed that it’s all very subjective, there’s really no debate possible. All I can do if I think abortion is very wrong, for example, is get a majority on my side and force you to recognize my values. Discussion is impossible. It seems to me that it’s just such an unhelpful way to think about values, given that we do have these opposed values in our society. We actually need the same kind of approach to value that we take to scientific facts.

Perlmutter: You see in history that people have actually moved each other’s understanding about what their values are. Slavery, at one point, would not have been seen the way it is today. And yet, now people have a shared a view of it.

MacCoun: It gets very muddled if you don’t distinguish facts and values. But there are ways of bringing them together in an analysis without just throwing your hands up. A lot of scientists, when they weigh in on public policy, haven’t really thought through some of this stuff, and they’ll just kind of weigh in with what’s basically just a value, but use the mantle of science. In the book, we talk about how it’s not enough to have all these habits of mind that scientists have unless you are in a community that will call you on your B.S.

Perlmutter: One thing that we highlight in the book is the idea that the particularly extreme inability to actually have a conversation that you often see in Congress — at least as presented to the public — is not necessarily the case for the whole society. I think if you take a random group of people in the public, they may disagree on a topic, but if brought into a conversation, they could actually have a conversation about it and try to figure out where the issue is coming from and maybe change their minds about certain topics, which seems to happen when you do these deliberative polls.

MacCoun: Part of the excitement of the book is that there are a lot of new ideas and innovations happening in that space of group decision-making. You have deliberative polling, the idea of don’t just poll people individually, but bring them together and have them talk together. And we talk about scenario planning. We talk about citizen forecasting methods that can outperform professional forecasters. And we talk about new open science models, where you pre-register your hypotheses, and open data. These ideas aren’t static, they’re developing all the time. And that’s part of what where the third millennium idea comes in. We’re getting collectively better at this stuff all the time.

BN: In reading about the process of collective decision-making — techniques such as deliberative polling, scenario planning and collective forecasting — it seems like an exhausting way to reach agreement.

MacCoun: It’s hard work, and I don’t think we’re glib in the book about this being necessarily easy. Conflict isn’t necessarily bad. Conflict can be ferocious and still be very productive, if you do it the right way. If you actually want to do things in the world, you’re going to have to, ultimately, sit down and talk to people that disagree with you.

Campbell: One of the revelations of social psychology is that we’re not bad at spotting biases in each other, but we are terrible at spotting our own biases. It’s just so important to try to create a world where it’s common knowledge that we’re all blind to our own biases, and that it really helps to have someone else around who could pick you up, who could check you on your biases. We have so much in our own heads orienting us in the wrong directions that we really need to clear that up a bit.

BN: But no one likes to be told that they’re wrong.

Perlmutter: That’s actually one of the reasons that we thought that there’s an extra advantage of the probabilistic style of thinking as a way of make sure you capture the information that’s really there without rounding everything off to be true or false. Many things we don’t know, but we do have a pretty good guess that it’s 85% likely to be true. And there’s an extra psychological advantage, which is that if you are committed to presenting all your findings as a probabilistic finding, then you don’t have your ego wrapped up in being right every time.

MacCoun: The problem is that the market rewards experts for overconfidence. I’ve been an expert witness in some of the trials involving gays in the military, and I was really pressed not to hem and haw and just tell me yes or no. I can’t do that.

We’re approaching an election, and we talk in the book about maybe we should start rewarding politicians for being straight with us. Little children find it very reassuring when their parents are all-knowing, but people of voting age are adults, and maybe we should recognize that politicians are not all-knowing. The ones who tell us, “I’m not sure, but this is my best bet,” or go a step further and say, “And if it turns out I’m wrong, I’ll change my mind and here’s my backup plan” — maybe those are the people we should be rewarding.

Campbell: You want to encourage conflict. Conflict is good. That’s the point of free speech. We have different ideas, we try to figure which one is right. Which ones are closer to the truth. But it’s hard to do that without getting inappropriately engaged. Freud had a word for it, cathexis, where your sexual identity becomes involved in maintaining the views that you’ve picked up, and it’s very difficult to let go of the thing. What we need is to have the debate, but have it judged in impersonal terms.

BN: Courses on the scientific method, critical thinking and decision-making are not new. How does your class and book differ from these?

MacCoun: Our book certainly overlaps with two very older traditions: courses or popular books on decision-making, and courses or popular books on critical thinking. Both elements are in our book, but a couple of things are distinctive about our book. It’s inherently interdisciplinary, given the nature of the authors, but we also feel like when people focus on decision-making or critical thinking, they just focus on the individual thinker, and they don’t really capture that that’s not enough. Even people who know about all these biases are still subject to these biases. It’s not enough to just do well as an individual. You really have to cultivate a community to make it stick.

BN: Your book ends on an optimistic note: that we can, in the third millennium, become more collaborative in our problem-solving.

MacCoun: The third millennium is very long. We gave ourselves lots of room to accomplish this.

Campbell: But that is the ideal of society. Everybody knows how to go about deliberating, how to go about discussion, as opposed to thinking they’ve got to win a majority and then bully the other side into submission. That’s really not a good way to go. That leaves you thinking about, “I’ve gotta use guns, because if debate is not possible, then agreement is not possible.”

Perlmutter: One of the things in science that seems to have been very effective is that it really sharpens your thinking when somebody is disagreeing with you. It’s very hard to see your own blind spots if all you have are people who share all your views. You actually should want to find the other party and have a discussion with them. But in this particular configuration that we’re looking at right now, it’s scary — it doesn’t feel like people are comfortable hearing somebody disagree with them and actually thinking, okay, is there something there that I’m missing that I could benefit from.

Take climate change. Climates change all the time, so whether or not we are the ones who started it — though we apparently have started this round — we have to deal with it one way or the other, and now we have to deal with it faster. I think we are perfectly capable of dealing with if we have some conversation and get people to sharpen up their ideas and work together. But it’s very hard to do it when everything is seen as a fight to the death or of not doing something that the other side wants.

BN: What do you hope to achieve with this book?

Perlmutter: In my mind, if people read the book and start to work together in the style that we’re advocating, I would feel much, much safer in the world we live in. I think it would be a noisy, argumentative world, as it should be — people will be trying to figure things out and arguing with each other, but they would be arguing with each other with the goal of actually solving problems together. And they would be, in the end, gaining a much sharper understanding of the reality in which we live. Groups of people, when well-structured, are amazingly capable. All the big concerns you might have about threats of climate change or pandemics or whatever, those are at just the scale that humans are today likely to be good at solving, if given the chance to actually talk together and try to make decisions together.

Campbell: Humans are fundamentally cooperative, though fundamentally tribal. What we need is to have a space where cooperation can happen between people with radically dissimilar views. That’s really the dream.

MacCoun: The U.S. military has learned this. There was tremendous anxiety about allowing gays and lesbians in the circle of military units. The concern was units are just going to fall apart because of differences in lifestyle choices, that the unit will disintegrate. And of course, that’s not at all what happened when they lifted the ban, because people had a shared sense of commitment to the overriding mission. To make a better society, you’ve got to have that shared sense of mission. If you have a shared desire to get somewhere for your community, but radically different ideas on how to get there, you can work it out. There’s lots of examples where people managed to work it out.