Generally, we assume it’s good to be smart. And we expect smart people to make generally smart decisions. But smart people may be so good at reasoning that they can logically reach the conclusion they want rather than the actual correct answer. In fact, maybe careful thinking isn’t all it’s cracked up to be.

Let me start this consideration of smart people making bad judgments by considering science and . Is the earth getting hotter? Do vaccines cause ? Is there compelling evidence for evolution? Is nuclear power safe? The scientific evidence is pretty clear with regard to these questions. Nonetheless many people refuse to accept the findings of scientific research. My original assumption was that people must not know the evidence. If people were better informed then they would generally agree with the scientific consensus. Better information and careful thinking should lead to better answers. I always thought that is the resolution to these political debates about science.

Turns out I was wrong. Being smart and informed is the problem in many cases. Smart people frequently reach bad conclusions about science in these politically important areas.

Smarter people seem to be more, not less, biased on these types of questions. This leads smart people to be particularly likely to reject scientific evidence. They are so effective at reasoning that they can reach the conclusion they want. Of course if smart people make bad decisions about science, they may be generally at risk for making bad decisions.

Here’s an example: One of my retired colleagues tracks the science and debate concerning very closely. He’s smart, he’s critical, and he reads. He also rejects the scientific consensus. He’s not convinced that the world is warming. He’s pretty sure that even if the world is warming, humans have nothing to do with it. Apparently he’s not unusual.

Why do lots of people reject the scientific consensus on global warming? Naively, I thought that they were simply unaware of the accumulating evidence about global warming. I suspected that they simply trusted some of the political figures when they heard those people complain about global warming. Others have suggested that it is something about how conservatives approach science (you could argue that in rejecting evolution, some have become used to rejecting all science). You could certainly make these arguments because many other smart and thoughtful people have made similar arguments.

But the scientific evidence provides another possibility. Being smart is part of the problem.

In several research projects, Dan Kahan and his colleagues have explored political polarization, particularly with respect to scientific questions. In case you’ve missed it, political debates in the United States have become particularly polarized. We have serious problems agreeing. In a good democracy, reasoned discourse and a concern for the facts should lead to a consensus. But we can’t even agree on the facts–even when the science seems clear. Kahan (2013) looked at several possible explanations for why people don’t agree on global warming. He investigated if conservatives were more likely to reject science or displayed more difficulties with critical thinking. Nicely, he found no difference in critical thinking skills between liberals and conservatives.

Next Kahan looked to see if people who reject global warming were simply those less likely to think through and evaluate evidence. You would hope that with better critical thinking and consideration of evidence, people would reach a consensus. He found the opposite. More extreme polarization followed more critical thinking. Smart people are really good at thinking critically; thinking critically about the evidence that is inconsistent with their general world view. Like most people, smart people have a set of beliefs and political attitudes. More than others, smart people like to think through problems and readily apply their critical thinking skills. The trouble is they reason through to the answer they want. Critical thinking leads them to support even more strongly the position consistent with their general beliefs. Liberals and conservatives disagree about the status of global warming and the difference is more extreme for those with stronger critical thinking skills. Being smart may not lead you to the right answer. Being smart enables you to critically evaluate and reject evidence inconsistent with your view. Being smart makes you better at supporting your preferred answer.

This isn’t just about global warming. In another study, Kahan, Peters, Wittlin, Slovic, Ouelette, Braman, and Mandel (2012) found the same pattern with respect to views about the risks associate with nuclear power use. Again people with higher critical thinking skills are more polarized than people less likely to engage critical thinking skills. In this case, however, the link between political perspective and science is flipped. Now the liberals with critical thinking skills are more likely to reject science and the conservatives to accept science.

In essence more information and better thinking skills can make things worse. For example, Nyhan and colleagues (2014) provided parents with various types of information about vaccines. The hoped to reduce concerns that vaccines cause autism (they don’t, really) and lead parents to be more willing to vaccinate their children. It didn’t work. More information didn’t change people much. Instead, they used the information to support their own views. More information can make us more extreme.

So what is the problem with thinking? Thinking is guided by our overall belief structures. We have ideas, often these ideas are associated with various aspects of our . I may be liberal or conservative or independent. I have some ideas about the general beliefs of people like me. When confronted with a problem domain, I have ideas about what the right answer is. I am more accepting of evidence that conforms to my pre-existing beliefs. I am more critical of information that is inconsistent with my views. I remember the consistent and reject the inconsistent. More information allows me to better support my position, even when that information is inconsistent with my position. For critical thinkers, they engage in these critical processes and become more extreme. In the political domain, thinking may not lead to consensus.

Is there hope then for our democracy? I think so. But it depends on people valuing reasoning above their personal political views. It will depend on a culture and world view that appreciates changing one’s mind.