If you're not a liberal when you're young, you've got no soul.
If you're not conservative when you're older, you've got no brains.
or "A conservative is a liberal who just got mugged."
Anyway, the gist of the man's argument is:
"Few conservative students ever become liberals during college, and vice versa. Higher education’s political influence may be less one of liberalization and more one of polarization, as centrist students gradually drift to one side of the spectrum or the other. Conservatives agitated over the idea of pervasive university radicalism are frothing at the mouth over nothing. Hard, statistical evidence pointing to a widespread “indoctrination” of college students into liberal thought simply does not exist.
What benign increase in the ranks of liberal students during college that does occur—roughly 4 percent—is not due to “indoctrination” at the hands of tenured socialists and radicals. It is, rather, a result of intellectual maturation combined with a stimulating collegiate social life that shapes and strengthens the values of equality and acceptance. If the lecture halls of America’s universities are “one-party classrooms,” as Horowitz says, maybe it’s because conservatism has forgotten that school is in session.