American public life is rife with questions of scientific judgment. Does red meat really cause cancers and heart disease, or are such fears overblown? How can scientists tell that climate change is occurring and what the effects of global warming might be? And, perhaps most poignantly, why should lay people trust scientists, given the histories of scientific support for eugenics; of medical doctors doubting the experiences of female patients; and of conflict among scientists over the safety of atomic power, the effects of cigarette smoke, and numerous other matters?

Perhaps no writer is better suited to address these questions than Naomi Oreskes, a trained geologist and historian of science at Harvard University. Her 2010 book Merchants of Doubt, cowritten with Erik M. Conway, introduced readers to the means by which a small group of scientists, allied with industry and the right, generated doubt about “inconvenient truths” from acid rain to global warming. That book, and the 2014 documentary film it inspired, revealed public conflicts over scientific “truth” to be the result of finely crafted public-relations campaigns. “Doubt is our product,” the tobacco industry proudly claimed in the 1950s. Merchants of Doubt showed just how that product continues to be manufactured.

In her newest book, Why Trust Science?, Oreskes takes on an even thornier problem: the manufacture and maintenance of trust. Based on her Tanner Lectures on Human Values, delivered at Princeton University, the book explores the pursuit of scientific knowledge and consensus across the 20th and 21st centuries, the changing conception of science from an individual to a social pursuit, and the reasons for and responses to science going awry. It convincingly demonstrates that “we are not powerless to judge contemporary scientific claims” and offers a ringing defense of the social and intellectual diversity of scientific communities as a key measure of trustworthiness.

Oreskes recently sat down with Andrew Needham, a professor of history at New York University, to discuss Why Trust Science?

Andrew Needham (AN): Let’s start off by talking about how you came to write this new book.

Naomi Oreskes (NO): In 2010, Erik Conway and I published the book Merchants of Doubt, which looks at what I call serial contrarians: people who systematically sowed doubt about a set of environmental issues, including acid rain, the ozone hole, and climate change.

Erik and I were trying to understand why someone would do that, particularly because the people we were looking at were scientists. They didn’t appear to be shills for ExxonMobil. It seemed that there was some other, more complicated story going on.

One of our early discoveries was that these people had been affiliated with the tobacco industry, and that they had challenged the scientific evidence linking tobacco to cancer, emphysema, cardiovascular disease, et cetera, et cetera. In our book, we demonstrated the role of political ideology. We showed how the “merchants of doubt” were committed to what we now know as neoliberalism (that word wasn’t really being bandied about back in 2005, when we started the book), but what we called free market fundamentalism. It’s the idea that government intervention in the marketplace is bad, free markets are good, and therefore any science that would imply the need for government regulation of the marketplace should be heavily scrutinized if not rejected altogether.

AN: Right.

NO: When we wrote that book, one of the things that we took for granted—one of the things we didn’t think we needed to explain—was why we should trust the science behind these issues. We more or less took it as a presumption that if there was a body of well-documented, peer-reviewed scientific work; reports from the National Research Council; reports from eminent scientific organizations like the Royal Society—that if there was a robust body of knowledge of that sort, then we, as the authors of the book, didn’t really have to question or doubt or defend that science. We could take it for granted that if the National Academy of Sciences had reviewed the literature and done a consensus report, then that science was probably robust. So, the question for us was: Why would anyone doubt that?

After the book came out and the politics of the situation evolved, it became increasingly clear that we really couldn’t take that for granted. It began to be clear that were a lot of people in the United States, and in some other parts of the world as well, who were not shills for ExxonMobil or the meat industry, people who did not necessarily own stock in Chevron or Texaco or Saudi Aramco or Peabody Coal, and yet who were, for whatever reasons, somewhat skeptical or suspicious of science.

This came home to me in a very forceful way when I went on the lecture circuit after Merchants of Doubt came out. The implicit message of my talk was: climate change isn’t a fad, this isn’t something invented by Al Gore. This is long-standing, well-developed science. It was developed by scientists who for the most part were not environmentalists. They were ordinary, nonpartisan scientists who had stumbled upon something that we would now call an environmental problem. But that wasn’t really how they thought about it at the time.

The point of all this, as I said, was to say to people: “Look, this is not just a fad, this isn’t just the latest craze.” Because often people would say that they thought it was. But it was long-standing, well-established, hard-won scientific knowledge.

After one of these lectures, a man in the audience stood up very aggressively, puffed out his chest, put his hands on his hips, and said: “Well, that’s all very well and good, but why should we trust the science?” I remember this moment very clearly because I recall thinking, “Yeah, that’s a good question.”

One of the things that you learn when you’ve been in the classroom for a long time is that, as we always say to our students, “There’s no such thing as a stupid question.” We always want to be sympathetic and empathetic, and even if our students clearly haven’t done the homework, we try to take on board the questions.