Adam Schaeffer of the Cato Institute manages the fairly impressive feat of beating up on me in a blog post (I am an "ingrate," along with Matt Yglesias and Felix Salmon) without mentioning or responding to the argument I was actually making. So hey, let me just go ahead and make it again: The tax code's definition of a charity is too broad. Do you disagree, Adam?
Still, the separate question Schlaeffer asks is an interesting one: "Why shouldn't we charge rich parents tuition to attend public schools? If a charitable deduction for private schools is so bad, why isn't a free public education even worse?" So let me take a crack at it.
In general, means testing public services is a good idea, for obvious reasons. A concept of justice that said, "everyone gets the same amount, regardless of how much they need or deserve" would not be a very convincing concept indeed. But the case for means testing is often overstated and sometimes treated as gospel. And I can think of five reasons why it shouldn't be:
1. Means testing creates some inefficiencies. Deciding to make some government service contingent on one's demonstrated need requires creating some administrative mechanism for measuring need. This is costly and difficult. It is also (as I'm sure I don't need to tell the good people of Cato) potentially incentive-distorting: limiting a public service to people below a certain income should, at the margin, reduce the incentive to rise above that income.