In this essay, I pull together thoughts on education, based on my reaction to Charles Murray's recent op-eds.
He tends to treat IQ as if it were a measure of one's capacity to hold knowledge, like the volume of a container. According to Murray, a high-IQ jar can hold advanced physics. A low-IQ jar can only hold, say, 4th-grade mathematics.
The container metaphor implicit in Murray's essays could be misleading. Instead, IQ might be a measure of the speed with which someone can absorb knowledge, rather than a measure of how much they can absorb. A high-speed car will get to the destination faster, but a low-speed car will still get there, if given enough time.
If the jar metaphor is correct, any resources devoted to trying to teach calculus to an average-IQ student are wasted. However, if the car metaphor is correct, and it is really important to teach calculus to the average-IQ student, then we should be putting more resources into doing so.
The economic approach to education would be to maximize benefits minus costs.
UPDATE: See also Seth Roberts, who has a somewhat similar take on Murray.