Political Scientist John Sides recently claimed that political independents vote for president in a reasonable way based on economic performance. John’s original post led to the amazing claim by New Republic writer Jonathan Chait that John wouldn’t “even want to be friends with anybody who” voted in this manner.

I’ve been sensitive to discussions of rationality and voting ever since Aaron Edlin, Noah Kaplan, and I wrote our article on voting as a rational choice: why and how people vote to improve the well-being of others.

Models of rationality are controversial In politics, just as they are in other fields ranging from economics to criminology. On one side you have people trying to argue that all behavior is rational, from lottery playing to drug addiction to engaging in email with exiled Nigerian royalty. Probably the only behavior that nobody has yet to claim is rational is blogging, but I bet that’s coming too. From the other direction, lots of people point to strong evidence of subject matter ignorance in all fields ranging from demography to the Federal budget to demonstrate that, even if voters think they’re being rational, they can’t be making reasoned decisions in any clear senses.

Here’s what I want to add. In the usual debates, people argue about whether a behavior is rational or not. Or, at a more sophisticated level, people might dispute how rational or irrational a given action is. But I don’t think this is the right way of thinking about it.

People have many overlapping reasons for anything they do. For a behavior to be “rational” does not mean that a person does it as the result of a reasoned argument but rather that some aspects of that behavior could be modeled as such. This comes up in section 5.2 of my article with Edlin and Kaplan: To model a behavior as rational does not compete with more traditional psychological explanations; it reinforces them.

For example, voter turnout is higher in elections that are anticipated to be close. This has a rational explanation—-if an election is close, it’s more likely that you will cast the deciding vote—and also a process explanation: if an election is close, candidates will campaign harder, more people will talk about the election, and a voter is more likely to want to be part of the big stories. These two explanations work together, they don’t compete: it’s rational for you to vote, and it’s also rational for the campaigns to try to get you to vote, to make the race more interesting to increase your motivation level.

I don’t anticipate that this note will resolve some of the debates about participation of independents in politics but I hope that this clarifies some of the concerns about the “rationality” label.

P.S. Sides is better at engaging journalists than I am. When Chait wrote something that I didn’t like and then responded to my response, I grabbed on a key point in his response and emphasized our agreement, thus ending the debate (such as it was), rather than emphasizing our remaining points of disagreement. John is better at keeping the discussion alive.

[Cross-posted at The Monkey Cage]

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Andrew Gelman is a professor of statistics and political science and director of the Applied Statistics Center at Columbia University.