Matt Yglesias, riffing on this eminently readable Julian Sanchez post, offers a pretty good theory for understanding contemporary left-right debates.

The left is simply less monolithic. It seems to me that if you look at the discourse among “green” types, you see groupthink there. And if you look at labor types, there’s another groupthink there. And there’s an immigrants’ rights groupthink and there’s feminist groupthink and all kinds of groupthink all around. But these points of view come into contact with one another and only partially overlap. At times they conflict. The progressive infrastructure contains people and institutions who are robustly on both sides of important questions like trade policy or K-12 education. Business groups are very involved with most Democratic Party politicians and with many progressives organizations (we have a “Business Alliance” at CAP). I think it would actually be beyond the intellectual powers of any one person to work all the sacred cows of all the different factions of the movement into a seamless and coherent whole. The right just isn’t like that. It’s less demographically diverse, less diverse in its financial base, and less ideologically diverse.

One of the virtues of Matt’s theory is its parsimony. The conservative coalition is diverse in many respects, but is is certainly more ideologically coherent than the liberal coalition, which, as Matt suggests, is more transactional, more interested in achieving incremental expansions of government power on issue of particular concern. You want a cap-and-trade system and a green industrial policy? That’s fine, as long as I get higher public sector salaries and a permanent system of racial preferences. In contrast, the right — for better or for worse — is organized around the principle of saying no to new expansions of government power and mostly acquiescing, in reality if not rhetorically, to old expansions of government power.

In his brilliant new book Never Enough, forthcoming from Encounter, William Voegeli writes:

All the liberal arguments point to a welfare state even bigger than Sweden’s; all the conservative ones to a welfare state smaller than pre-New Deal America’s. The welfare state we actually have limps along, lacking enthusiastic support and a compelling rationale that could explain how to improve it without making it radically larger or smaller. Liberals and conservatives are both in the awkward position of reassuring voters that they don’t really mean what all of their arguments clearly do mean. As a result, neither of them can muster the syllogisms or the votes to change the welfare state we’re stuck with.

But would this problem on the right be solved by less groupthink? Or should an ideologically coherent group move collectively away from arguments that are straightforwardly anti-statist to arguments that are more focused on value for money? The ideological through-line, about the dangers of unsustainable state expansion, remains the same; the arguments, however, would reflect more of a real-world engagement with near-term policy issues. As Voegeli suggests, this would move left-right debates from a philosophical terrain, where the left is strong because it is vague and hard to pin down, to the more practical question of what we can and can’t afford, i.e., would the median voter have the same appetite for taxpayer-financed public services if we were all paying enough taxes to pay for current spending, of if we even came close?