Matthew Yglesias disagrees with Paul Krugman that conservative and progressive political philosophies are irreconcilable:

The strange thing is that so much of this furious opposition to activist government appears to be make-believe. The American Enterprise Institute did a poll of self-identified conservatives and found that “only 3 percent of respondents favored reforming Social Security and Medicare.” The 2010 elections put a lot of new conservative governors in office, and I’m guessing that exactly zero of them will abolish mandatory minimum parking requirements in their states. Nor do I expect to see Rep Frank Lewis slash farm subsidies.It’s a bit puzzling. The gap is really not just between conservatives and non-conservatives, but between conservatives’ self-image and the reality of their program. Paul Ryan, for example, can’t quite seem to decide if he wants to slow the growth of Medicare while maintaining a credible safety net for elderly Americans (in which case his “roadmap” proposal is the starting point of a discussion) or if he’s an Ayn Rand devotée who’s trying to liberate America from enslavement at the hands of the welfare state. Indeed, he doesn’t really even seem to see that these are different ideas!

I don’t find it as puzzling as Yglesias does.  The political process has a specific set of incentives that will shape the career of all successful politicians.  In general, Politicians try to win voters and campaign funds by appealing to concrete, discernible interest groups: agriculture, the banks, the middle class, the elderly, unions, doctors.  Voters pursue their interests much more effectively by protecting their own particular entitlement than trying to simultaneously repeal all the other entitlements.  There is a political prisoner’s dilemma; the equilibrium of political incentives will always be very far from Republican small-government rhetoric.

Conservative politicians succeed both by pandering to interest groups for votes (the elderly, for example, in the last election) and by wooing ideological conservative voters with small government-platitudes.  In other words, they succeed by pursuing incompatible principles.  Democrat voters, on the other hand, usually like rhetoric about extending additional government support to (certain) interest groups (e.g. the sick, the poor, the uninsured, teachers, doctors).  The only hard choices that Democratic politicians have to make is how hard to push for their priorities – and which come first.  A “small-government” politician needs to be a hypocrite to succeed.