One of my favorite intellectual puzzles is figuring out what deep conceptual presuppositions cause some people to be conservatives, other people to be liberals. That is, on a range of issues that would seem largely unrelated—say, abortion, affirmative action, and gun control—it turns that people’s positions are highly correlated. For instance, people who are pro-life tend also to be against affirmative action and against gun control, whereas people who are pro-choice tend also to be in favor of affirmative action and in favor of gun control. Why is this?

I’m still working on a general solution, but one thing is pretty clear. Conservatives tend to think that demand curves are elastic, liberals that they’re inelastic. Economists talk about demand for a product or service as being elastic if a 1 percent increase in price produces more than 1 percent decrease in quantity sold, inelastic if a 1 percent increase in price produces less than a 1 percent decrease in quantity sold. Elasticity is a precisely defined concept, but the basic idea is easy enough to understand: Roughly, demand is elastic if, when you raise the price, people just pay the higher price regardless, but inelastic if, when you raise price, people stop buying the product and do something else with their money.

So, for example, conservatives think the demand for crime is elastic: if you raise the price of crime to the criminal by increasing prison sentences, you’ll get a lot less crime. Liberals, on the other hand, tend to think that increasing prison sentences will have little effect on crime rates. In other words, they think the demand for crime is inelastic relative to prison sentences. Similarly for taxes. Conservatives tend to think that if you raise income taxes, people will work a lot less, whereas liberals tend to think that you can raise income taxes and not much affect how much people will work.

A fascinating role-reversal is thus at work in the voting rights cases that the United States Supreme Court heard earlier this week. As this story in the Legal Times explains, the Court is considering a constitutional challenge to an Indiana statute that requires citizens who want to vote to produce a state-issued photo identification such as a drivers license.

Conservatives generally favor the law, and liberals generally oppose it. In particular, the Indiana Democratic Party and the ACLU say that the law is unconstitutional because it will deter people—especially old people, the poor, and minorities—from voting. They are thus in effect saying that the demand for voting is very elastic: Make it even a little more difficult for people to vote, and they’ll stay away from the polls. The conservative supporters of the law, on the other hand, are saying just the opposite: raising the effective cost of voting will not affect how many people vote because the demand for voting is inelastic.

Where does the truth lie? I’m a conservative, and so I usually think that demand curves are pretty elastic. Nevertheless, I also think that the Indiana statute would not deter many people from voting and so ought to be held constitutional. If I ask myself why I think this, however, and if I’m being completely honest, I would have to say that I don’t really know.