I am getting a little impatient with all of these self-defined "progressives" who won't admit their mistakes. (Obviously there are analogs of this habit in every movement; the progressives don't have a monopoly here.) We all got a chuckle over Paul Krugman ridiculing the very IDEA that he could have called for a housing bubble, and today we get to see Matt Yglesias laugh off Alex Tabarrok's clear busting of him.

Okay so here is the progression:

* On May 30, 2009 Yglesias wrote:

This goes back to a point I was making a while ago about how dangerous it is that the public discourse is so dominated by low-quality freelance philosophy done by people with PhDs in economics. I’m fairly certain that if Mankiw were to walk over to Emerson Hall he could find some folks (possibly T.M. Scanlon who I know sometimes reads this blog) who could explain to him that there’s little grounds for the belief that a commitment to utilitarianism is the main justification for redistributive taxation.

* Then on July 20, 2009 he wrote:

...the point here is that the marginal utility of money income declines as it grows. This is also a strong argument for believing that redistributing money from wealthy or high-income individuals to the poor or to public services will be welfare-enhancing.

Tabarrok pointed out the above contradictions, in a post titled, "Yglesias vs. Yglesias." Then Yglesias says today:

Contra Alex Tabarrok’s cute post here there’s nothing contradictory between pointing out that Greg Mankiw is wrong to imply that utilitarianism-based arguments are the only (or even the primary) arguments available for redistributive taxation and also to point out that considerations related to the declining marginal utility of money do, in fact, militate in favor of redistributive taxation.

Give me a break, Yglesias. Just say, "Heh, you got me there, Alex. At least I know there was a housing bubble."

Yes, it's logically possible that one could have pointed out that Mankiw was wrong, while simultaneously arguing that utilitarian considerations "militate in favor of" redistribution. (By the way, Yglesias, you're aware that many economists--and philosophers--think it's impossible to engage in interpersonal comparisons of utility, right?)

But that's not what you did. Here is a bigger quote from your July 20 post, after you summarize some of Will Wilkinson's objections to using income inequality as a basis for tax policy:

At the same time, the point here is that the marginal utility of money income declines as it grows. This is also a strong argument for believing that redistributing money from wealthy or high-income individuals to the poor or to public services will be welfare-enhancing. The difference, in welfare terms, between a Sub-Zero refrigerator and an Ikea refrigerator is much smaller than the difference in welfare terms between having health insurance and not having health insurance. So a surtax on high earners that goes to finance expansion of health coverage to the working poor is making people better off. In that case, when we look at statistics indicating skyrocketing income inequality we’re seeing evidence of inefficiency that can be rectified through the policy process.

The crude utilitarianism you mention here is the only justification you give for redistribution, to oppose to Wilkinson's critique. And you specifically say "the point here is".

So you're saying that "the point here" is something that isn't the main justification, a main justification that you failed to mention in the post when arguing for progressive taxes?

To repeat, it's theoretically possible that you didn't contradict yourself, but c'mon, Tabarrok busted you. Just admit it and move on. We all screw up from time to time. It's hard work pontificating on everything under the sun!