Those interested in the topic may find this recent EconTalk episode interesting (the transcript is pretty good if you'd rather read than listen) in which Russ Roberts interviews fellow economist Bryan Caplan about the value of a college education. Caplan is a proponent of the signaling model of the value of a college degree. According to this model, the economic value assigned to a college degree (the extent to which employers require it or pay more to people who have one) is not primarily a matter of what you learn in college (the skills acquisition model) but rather a matter of signaling that you are the sort of person who can get into college and then stick with it and earn a degree. One of the things that Caplan points out in support of this view is that virtually no value is assigned to having completed most of college (say if you stop one course short of getting your degree) -- which in a skills acquisition model is not necessarily what you'd expect.
Here's a bit of the transcript where Caplan lays out how the signaling theory and the wage gap interact according to his thinking:
Bryan: So, in 2011, college graduates made 83% more than high school graduates. And high school graduates, mainly people who have gone to college not at all.
Russ: How has that amount changed over time?
Bryan: It's gone up quite a bit. So, maybe around 1970 it would have been only about 35 or 40%, so it's something like doubled over the last 40 years, during my lifetime.
Russ: And what are some of the standard explanations for why that's happened? So, why is college more productive for people who attend and have graduated?
Bryan: The usual story is that there has been a lot of psychological change in the economy, globalization as well, and that this has somehow made it more important to be a college graduate. And among most economists, they do tend to focus on the skills that you supposedly receive in school. And so they think of it as: it's more important to have general thinking ability and reasoning skills, as well as different technical skills you might learn in school; and that when the economy is more technologically complex, and also when you are competing in a global market where one person could mess up a big firm, it's more important to have these skills. I'd say that's probably the usual view.
Russ: And what do you think of that view?
Bryan: I think that there is some truth in it, but it's greatly exaggerated and there's a lot of other things that are going on that most people who study education would rather not talk about.
Russ: What are a few of those?
Bryan: Well, one of the main ones, strangely, for economists to ignore is--even though they do--is that people who go to college are not the same even when they start. So, the kind of person who goes to college is different at the beginning. And there are a lot of reasons to think that people who are different in the beginning would have made more money even if they hadn't gone to college. The most obvious one is that people who go to college are generally smarter. It's not popular to say it, but all of the evidence confirms it. And they were smarter before they started. Now, there's also a lot of evidence that--
Russ: We'll get into that later. But why would that have changed over time? This is the reason--this is an incredible change, right? I don't think there is any parallel development in the area of education over any other time period, 30, 40-year time period, a doubling of the returns to education. You are suggesting that--you started by saying that the standard answer, which is, well, the world is more complex, there's all this technology, and so college students are more valuable--you are not convinced of that. I'm not either, by the way. I used to be more sympathetic to that until I started reading you. So, I'm interested: Why would think that would change over time?
Bryan: Right. Well, again, there's an important distinction to make. You need to distinguish between college graduates being more valuable and college itself being more valuable. Those are two different things. So the main problem that I have with the usual view is that I take a look at what people actually study in school, and I see very little evidence that most students are acquiring any technical skills. And also, surprisingly, when I read educational psychology, there is a lot of question about whether college students are actually learning much in the way of thinking skills, either. So, a more reasonable story is not so much that the skills that college teaches are more valuable than they used to be, but rather the kind of people who go to college are more valuable than they used to be. Which is quite different.
EconTalk is a consistently very high quality interview show, and this one in particular is worth listening to if it's a topic that interests you.