KEVIN DRUM draws our attention to an intriguing paper Martin Gilens, on the responsiveness of policy to preferences across income groups. Here are the key charts:

At left, we see that as people at the bottom of the income spectrum care more about an issue, the probability of action on that issue scarcely budges. At right we see that policy responds a little more to median preferences. But what's clear in both is that the rich are much more successful at getting their issues on the docket. That's not really that surprising, but why should it be the case? Mr Drum writes:

Gilens' guess is that "the most obvious source of influence over policy that distinguishes high-income Americans is money." This sounds like a pretty good guess to me.

Specifically, Mr Gilens looks at a range of potential causal and non-causal explanations of the connection, eliminates some that don't seem to correspond with available data, and concludes that the striking responsiveness of policy to the preferences of the rich is probably due to the one characteristic in which the rich are strikingly unique, namely, their richness.

Matt Yglesias offers a different view:

I would say the most obvious mechanism here is socialization. The president, the senior White House staff, the cabinet secretaries, the senators, the House members, the senior congressional staff, and the lobbyists, association heads, business executives, governors, mayors, foreign officials, and media celebrities who they interact with are all personally pretty high income... What's more, political elites tend to have college roommates, siblings, in-laws, etc. who are also prosperous. Obviously the fact that rich people have money to spend on politics doesn't hurt either. But I would never underestimate the human desire to believe that one is doing the right thing, and thus the importance of socialization to determining bias.

The idea here is that elected officials care about the rich because they and their friends are all rich. There's nothing particularly pernicious here; the people who matter simply look at what the people they know care about and conclude that that's what people, generally, care about.

Mr Gilens actually proposes and dismisses this explanation:

[W]ithin any economic stratum there exist individuals with a wide range of policy preferences and this would appear to be true among federal policymakers as well as the public at large. That is, although every Senator and Representative is well-off, the range of policy preferences represented appears to be quite wide. Affluent liberal Democrats as well as affluent conservative Republicans battle over federal policy. In terms of understanding responsiveness of government policy to public opinion, the key question is not what the preferences of elected representatives are, but why a particular set of affluent lawmakers, with a particular set of policy preferences, was elected. Given the range of policy views represented in congress, it seems unlikely that any coincidence of preferences that exists between lawmakers and well-off Americans is the result of the economic status of lawmakers themselves rather than the electoral system that produced a given set of lawmakers.

In other words, rich Democrats and rich Republicans elect politicians with a diverse range of views, but all of which ultimately respond to the policy preferences of the rich. To put this slightly differently, we all know rich people on the left side of the political spectrum who care passionately about the poor and have no problem supporting policies that aren't necessarily in their own direct interest. These people exist. But the Democrats who end up in Congress tend not to be these people; they're the kind of people who respond to the preferences of the rich. Who knows what their motivations for doing so are; perhaps they view concessions to rich priorities as necessary in order to survive in Washington to fight for other priorities some other day. And it should be noted that the priorities of middle and low income voters are occasionally heard and addressed.

But the asymmetry here shapes the policy that emerges from Washington. Legislators worried about the poor often have to cut deals to satisfy the rich people who support their campaigns and other critical institutions. Legislators worried about the rich basically never have to make these kinds of concessions. Money, by creating this asymmetry, gets what it wants much more often. As Mr Gilens notes, this is a feature of very nearly every political system in very nearly every historical era. What I would suggest is that it is therefore not a tremendous threat to democracy, except in cases when mobility levels across incomes fall dramatically. In that case, you create a permanent class of politically disenfranchised people. And that can be a very destabilising thing.