Education is a multiplier of IQ, not an equalizer. Many people, although policymakers won't admit it, don't have the IQ to study at the high school level, for example learning algebra. Even more people don't have the IQ to study at the college level, for example studying calculus and writing a coherent, footnoted term paper. And only a small fraction of the population has the IQ to do significant research and earn a…
Sure, all other things held equal, maybe inherent intelligence is the limiting factor. But that's the point -- not everything else is equal. There are barriers other than IQ preventing people from achieving more, and I think we'd all be better off helping them overcome those barriers.
Besides, IQ tests are a pretty phony measure of intelligence. They're about as reliable as lie detectors.