A âphilosopher of scienceâ on climate change deniers: âPeople can actually change their mind based on factsâ
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Kara Holsopple/The Allegheny Front
How do you change the minds of climate deniers and people who doubt the scientific process in general? We ask a philosopher of science for some answers.
Lee McIntyre is a research fellow at the Center for Philosophy and History of Science at Boston University and a lecturer in ethics at Harvard Extension School. He has written books about defending science and fighting back against âalternative facts.â

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Lee McIntyre
Now, McIntyre is out on the road talking to flat-earth theorists and people who donât accept current climate science. The Allegheny Frontâs Kara Holsopple spoke with McIntyre when he visited Pittsburgh this week.
Kara Holsopple: What are some of the myths about science that climate deniers and others use to defend their points of view?
Lee McIntyre: I think that some of the myths that people have about science are not just ones that climate change deniers have, but really all science deniers. One is that scientists have to achieve certainty. That they have to prove their results, otherwise theyâre not worth believing in. âAny theory is as good as any other.â
So, youâll sometimes hear people say about evolution, that evolution is just a theory. With climate change, people tend to say things like, âWell you canât prove it; we donât have all the evidence; letâs wait until more evidence comes in.â
Itâs part of the same myth. Itâs this idea that until you have 100 percent certainty, nothing is worth believing in. Thatâs just not how science works.
KH: How can scientists and others combat those myths?
LM: One thing that scientists can do is just embrace the idea of uncertainty. They understand that with any empirical endeavor, thereâs always the possibility that more evidence will come in and change the theory, look when Newton got overthrown for Einstein. No matter how well ensconced your theory is, thereâs always the possibility of future evidence.
âPeople can actually change their mind based on facts.â
Scientists know this. But somehow when theyâre defending science to the lay public, they want to oversimplify and they seem to want to say, âWell no, this has been provenâ or âWe know this.â And thatâs deadly, because then if a science denier or a critic of science figures out that thereâs actually this one piece of evidence that [scientists] havenât accommodated or [is] this other study, then [scientists] look bad.
So my theory is that scientists just need to embrace the idea of uncertainty and talk about what they really believe, which is the idea of âwarrant.â You believe things based on how strong the evidence is. There are always error bars but that doesnât mean that you donât have evidence for what you believe.
KH: So is it a question of scientific literacy. How can scientists communicate that to laypeople?
LM: I think examples are one good way to do it â stories about how science works, not just always speaking in the abstract. Iâll give you an example. About five or six months ago, Reuters reported that the evidence for anthropogenic climate change was now at the 5 sigma level, which means that there is a one out of a million chance that itâs not human caused. I think that people understand that.
âWhat else can you deny the truth about? Maybe the path of a hurricane.â
KH: So from what youâve learned, is there sort of a way forward understanding climate denial and then possibly changing minds?
LM: I think that we need to change the way that we talk about it. I think that hitting people over the head with facts making them feel stupid, causes them to shut down. People can actually change their mind based on facts. Thereâs now been some empirical work on this.
There was a terrific study out of Germany that appeared in Nature in June 2019 that talked about science deniers or at least the audience for science deniers changing their mind based on presentation of facts. But it depends on how you do it. I think that face-to-face is the way to do it. If you read the literature about how people actually do change their minds, itâs always on the basis of somebody that they trust. Itâs always on the basis of an encounter with a human being who takes their doubts seriously and talks them through it.
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Thatâs true for anti-vaccines. Thatâs true for climate change. And Iâm now out there on the road trying this myself as a philosopher of science â to see if I can not just study climate change, not just study science denial, but see if I can work out a method, work out a script or just a way of caring, to talk to people about their beliefs about anti-vax, flat earth, climate change, evolution. Itâs really important that people do form their beliefs based on facts and I want to figure out how to do that well.
KH: These are topics that people have very strong feelings about that come from their backgrounds or from where they live. So how do you move from feelings to evidence, which is what science is based on.
LM: I think it comes back to what you care about. It comes back to the process by which your beliefs are formed. For some people, you donât really need to convince them that they should form their beliefs on the basis of evidence. Actually, if you look at people who are deniers about climate change, maybe you donât even need to convince them, because they tend to be what I call âcafeteria skeptics.â Theyâre skeptics about climate change because they donât want to believe in climate change but theyâre not skeptics about chemotherapy. Theyâre not skeptics about air travel. Theyâre not skeptics about you know all sorts of things that they actually do care about.
Iâve been having these conversations with science deniers and with others around these topics [to understand] how to assess what it is that people care about. I think that thatâs actually the route to changing peopleâs mind.
âEvery piece of misinformation has an audience.â
There are well-known cases, [like] Jim Bridenstine, who President Trump appointed to be the chief administrator at NASA. Bridenstine was a climate change denier when he was in Congress. He was only in NASA for I think a few weeks before he changed his mind on climate change, which was amazing. It was based on his conversations with NASA scientists. He knew the evidence, but it was when he met the people, he got to know them, he got to trust them. Thatâs when he changed his mind.
KH: Your book, Post Truth, talks about how science is under attack. Are we in a new phase or is this an example of something thatâs in line with what youâve seen before or a trend?
LM: I mean technically I guess it goes back to Galileo and even before. In the modern era, if you read Naomi Oreskes and Erik Conwayâs book, Merchants of Doubt, they talk about how modern science denial started with denial over the link between cigarette smoking and cancer in the 1950s. That really created a blueprint that was used for all sorts of science denial for the next 70 years.
I think what happened is a number of people noticed that that was a very effective campaign. It was extremely effective to deny climate change, to deny evolution, acid rain, ozone, all sorts of things. I think that that caught the attention of some politicians who said, âIf you can deny the truth about cigarette smoking and cancer, if you can deny the truth about acid rain and ozone, what else can you deny the truth about?â Maybe how many people were at inauguration. Maybe the path of a hurricane.
The thing that I realized in the course of my own research is that every lie has an audience. Every piece of misinformation has an audience. If you donât stand up to the person whoâs misrepresenting the facts, whoâs telling the lie â if you donât stand up for what whatâs actually not only true, and the process by which true beliefs are formed, thereâs going to be a whole extra generation coming up behind them.