The annual AAUP faculty salary survey is out, and one finding is that the pay differences between fields are growing. One reason for this is that in certain disciplines PhDs can command large salaries outside of academia - think medicine, engineering, business. That's one reason education is at the lower end; while we can get jobs other than as professors, the pay isn't superior. But it's also about supply and demand.
The article quotes someone from the MLA (the humanities academic group): “The gap in pay worries me because it might discourage those who want to teach language and literature." I would argue that discouraging them is precisely what we ought to be doing. There is an enormous oversupply of English PhDs relative to the number of openings, and there isn't a ready career alternative for them that justifies getting a PhD. If anyone in the field wants a job or a good salary, it's in his or her interest to discourage would-be doctoral students. That kind of practical yet dream-killing advice is only taken seriously by economists, however.
Of course, we have our own problem in education, so don't think I'm smug, but too many qualified PhDs isn't one of them.