Neal McCluskey:

At this point, I think I’ve said all I need to about the doubling of interest rates on subsidized federal student loans. Basically, the doubling won’t have a big impact one way or another, but putting a little more payment burden on the students consuming higher education is probably a good thing. Why? Because cheap aid encourages students to demand stuff they otherwise wouldn’t, and enables colleges to raise their prices at excessive rates.
That said, since the nation will likely be talking about student aid for a while longer, now is probably a good time to reprint – and expand – the list of empirical studies that have, in one way or another, found that schools in large part capture aid money rather than becoming more affordable. The list probably isn’t exhaustive, and there are many limitations that make it impossible to prove that aid fuels inflation, but combined with the logic that you’ll willingly pay more if you have someone else’s money, these studies show that there is very good reason to conclude that aid is counterproductive:
John D. Singell, Jr., and Joe A. Stone, “For Whom the Pell Tolls: The Response of University Tuition to Federal Grants-in-Aid,” Economics of Education Review 26, no. 3 (2006): 285-95.