Ezra Klein has the link to a fascinating paper by Larry Bartels and Christopher Achen about the ugly reality behind political decision-making. Rather than try to summarize the paper, I’m going to steal this one graph and talk about it, since I think it encapsulates things nicely:
The horizontal axis plots people’s self-report about where they stand on the left-right spectrum on spending issues. The vertical axis plots people’s self-report about where they stand relative to the Republican Party on the left-right spectrum on spending issues. The chart separates the answers out into one line for Democrats and one line for Republicans. Partisanship, however, is logically irrelevant to this question. Two people who self-identify as having the same view on spending ought to be the same distance from the Republican Party, even if one person is a Democrat and one is a Republican. But, as the authors observe, “they are markedly divergent, especially for people whose own positions do not happen to fall at the midpoint of the 7-point scale.”
If you ask some different kinds of questions, you’ll see that people usually vote for the party that they think reflects their views. One might think this means people are looking at where the parties stand, comparing that to where they stand, and then voting for the party they prefer. Bartels and Achen, however, use their way of looking at the data to argue that this is backwards — people are committing to a political party, and then having done so simply convincing themselves that the party they’re committed to shares those views.