In the Republican primary, almost all of the candidates are presenting themselves as committed conservatives. The one clear exception is the one who's surprised everyone by jumping into first place and staying there. Under those circumstances, you'd expect some of the others to emulate him, not by taking exactly the same positions, but by deviating from orthodoxy on some things and cultivating an image of someone who says what he thinks and doesn't care about labels. But there's no sign that anyone's doing that.
Paul Krugman notices the same phenomenon, which he calls "crankification." The term is a bit unfair--it might be more accurate to call it something like "convergence on extreme positions." It's not surprising that a Republican would want to cut income taxes on high incomes, as Jeb Bush's plan does, but the scale of the cuts proposed is at the margins of credibility. Other non-Trump candidates are offering even more fanciful proposals for enormous tax cuts. I haven't heard anyone proposing any moderate changes like taking the top rate back to 35%, where it was under GW Bush.
Krugman offers an explanation for the positions on taxes: the candidates are doing what rich people (ie, big donors) want. I think there are several things wrong with this explanation. This first is that according to a paper by Benjamin Page, Larry Bartels, and Jason Seawright on the policy preferences of the wealthy, people with high incomes are not demanding big tax cuts. The mean preferred top marginal rate is 34%, lower than we have today but higher than Bush is proposing. The mean preferred estate tax is about what it is today for estates of ten million, and probably somewhat lower than it is today for estates of $100 million--but Bush is proposing to eliminate the estate tax. Also, 65% if the sample said they'd be willing to pay more in taxes to reduce the budget deficit. In general, the picture was that the average rich person was what used to be a mainstream conservative, along the lines of someone like Bob Dole. Their sample was just from the Chicago area, and I'm sure that rich people in some parts of the country tend to be more conservative, but I also expect that rich people in the Northeast and West coast are less conservative. The second, and the one I'll focus on in this post, is that "crankification" is present even among Republican opinion leaders who aren't running for office.
I'll take Ross Douthat as my example, since he's a conservative reformer who holds that the Republicans should be trying to help the middle and working classes. In an analysis of the Rubio-Lee tax proposal, he says that it doesn't "get within even distant hailing distance of being revenue neutral" and offers some ideas about what Republicans should do. His primary goal is to reduce "the tax burden on people struggling to stay in the middle." Since he's realistic, he says that means increasing taxes on someone else. Specifically, his ideal tax reform "would end up raising taxes on some of Thomas Piketty’s petits rentiers (the upper middle class, that is) while probably cutting them somewhat for the super rich." Piketty defines petits rentiers as people who get "substantial and even fairly large inheritances: 200,000 ... or even 2,000,000 euros." The obvious way to increase their taxes would be to radically reduce the estate tax exemption, which I'm pretty sure is not what Douthat wants to do. I think what happened was that he interpreted the term as "rent-seeking," or using political power to get special treatment or protection from competition. There's a long tradition, going back to Adam Smith, holding that a lot of inequality is the result of rent-seeking rather than the workings of the free market. That's what Douthat means by the "on the tax code’s pro-rentier bias": not that the tax code is biased in favor of people with savings, but that it's filled with breaks for "special interests." The obvious problem with his proposal, which he doesn't even address, is the assumption that the upper middle class benefits more from rent-seeking than the super-rich do. Who is more likely to succeed if he calls up his Senator to ask for a favor, me or Donald Trump?
So coming round to my theory of crankification, I think the cause is that conservatives, even conservative reformers, are concerned with proving that they are conservative. Douthat could have said that we couldn't pay for government programs entirely by taxing the rich, that we would have to raise taxes on the upper middle class too. Or he could have said that we should reduce rates but eliminate most deductions, and if that turns out to mean that the rich paid more in taxes, then so be it. Or he could even have said that we should use the anti-trust laws to promote competition. All of those would have made more sense than what he did say, but they could be seen as concessions to the center or the left.
When he dropped out of the race, Rick Perry said that "I step aside knowing our party is in good hands, as long as we listen to the grassroots, listen to the cause of conservatism." That last bit is telling: rather than saying we should listen to "Republicans" or "Americans," he said we should listen to the "cause of conservatism." That raises the question of how conservatism became a cause. Traditionally, conservatism was seen as a collection of prejudices or practical wisdom (depending on who you asked): "causes" were for the left. I hope to have a post on that within the next few weeks.