Slate's Eliot Spitzer (yes, that very one) thinks the way we pay for higher education is bonkers, and he's right. College costs too much. It's a financial deterrent that prevents people from pursuing degrees and career paths of social (but not financial) reward-or from attending altogether. His solution has been been praised by (otherwise diametrically opposed) thinkers Milton Friedman and James Toobin Tobin. It's the income-contingent loan. Or, as he puts it, the smart loan:Instead of paying upfront or taking loans with repayment schedules unrelated to income, students would accept an obligation to pay a fixed percentage of their income for a specified period of time, regardless of the income level achieved. Suppose a university charged $40,000 a year in annual tuition. A standard 20-year loan in the amount of $160,000 (40,000 times four) would produce an immediate postgraduate debt obligation of $1,228.50 per month, or $14,742 per year, not sustainable at a salary of $25,000 or anything close to it. Under a smart loan program, the student could pay about 11 percent of his income, with an initial payback of $243 per month, or $2,916 per year, which is feasible at a job paying $25,000. If, after five years, the student's salary jumped to $100,000, payments would jump accordingly and move up over time as income increases. After 20 years, assuming ordinary income increase, the loan would be paid off.There are all sorts of questions to be asked of this idea's application, but the idea itself seems dead on. What do you think?Photo, "The Registrar's Office," by Flickr user specialkrb.