Republicans are much more likely than Democrats to think that Barack Obama is a Muslim and was born in Kenya. But why? People choose to be Republicans or Democrats because they prefer the policy or ideology of one party or another, and it’s not obvious that there should be any connection whatsoever between those factors and their judgment of a factual matter such as Obama’s religion or country of birth.
In fact, people on opposite sides of many issues, such as gay marriage, immigration policy, global warming, and continued U.S. presence in Iraq, tend to disagree, often by a huge amount, on factual matters such as whether the children of gay couples have more psychological problems than the children of straight couples, what are the economic impacts of illegal immigration, what is the effect of doubling carbon dioxide in the atmosphere, and so on.
Of course, it makes sense that people with different judgment of the facts would have different views on policies: if you think carbon dioxide doesn’t cause substantial global warming, you’ll be on the opposite side of the global warming debate from someone who thinks it does. But often the causality runs the other way: instead of choosing a policy that matches the facts, people choose to believe the facts that back up their values-driven policies. The issue about Obama’s birth country is an extreme example: it’s clear that people did not first decide whether Obama was born in the U.S., and then decide whether to vote Republican or Democratic. They are choosing their fact based on their values, not the other way around. Perhaps it is helpful to think of people as having an inappropriate prior distribution that makes them more likely to believe things that are aligned with their desires.
The interaction between a person’s values and their judgment about factual matters has long been noted. For instance, Upton Sinclair said “It is difficult to get a man to understand something, when his salary depends upon his not understanding it!” To give an example: North Atlantic cod fishermen did not understand that they were overfishing their stocks, right up until the cod population collapsed.
I want to be very clear that I’m talking about how people judge facts, not values. Some people might want to restrict fishing because they like preserving a more natural ecosystem that includes fish and orcas and sea lions, while others might want less restricted fishing because they want to make more money or because they want cheaper fish. These groups might disagree about fisheries policy because they have different goals. That’s very different from disagreeing about a fact, like “how many North Atlantic cod will there be next year, if we catch N of them this year”?
People often seem to reason “backwards,” making their judgment about facts based on the implications of those facts, rather than the other way around: “If we are overfishing, then we will not be able to catch as many fish next year. That will be an economic disaster for me. Therefore we are not overfishing.”
I used to think that when people’s judgment about facts seemed very wrong, in a direction that obviously matched their personal ideology or desires, they were lying. Cigarette companies know cigarettes are addictive, fishermen know they are overfishing, Senator Inhofe and Richard Lindzen know carbon dioxide causes global warming, and so on. But I was wrong about that. There is a very strong tendency for people to believe what they want to believe, when their lifestyle is at risk, as Sinclair noted, but also when their culture or ideology is threatened.
I don’t know what to with the knowledge that people, including (I presume) me, are biased in our judgments about facts. I think that to some extent forewarned is forearmed — I think recognizing ones’ own biases can help to overcome them.
I also think that recognizing the interaction between desires and factual judgments can help figure out how to influence or persuade other people. If you think people who espouse wacky beliefs are lying, you treat them very differently compared to realizing that they are fooling themselves.
Related reading on this blog includes the following posts, most of them focused on beliefs about climate change and some of which have interesting or entertaining comments:
Who’s your favorite expert, by Andrew Gelman