Capital is both heterogeneous and specific. Human capital exhibits the same tendencies.
One unfortunate side effect of the “everybody must go to college” attitude prevalent in America (though hopefully waning a bit as a result of the number of recently-graduated people with large debts and nothing but College of Arts degrees and aspirations for becoming even baristas) is that the entire realm of blue-collar, skilled labor has become almost taboo. Mamas, don’t let your kids grow up to be plumbers. Send them off to learn art history instead.
Tying Jerry O’Driscoll to Ludwig Lachmann (as if the first sentence didn’t do that well enough…): human capital is heterogeneous. Just because you went to college doesn’t mean that you can automatically perform any type of job. Going to college (theoretically) can help you perform certain types of jobs: going to a good engineering school can help you become an architect, electrical engineer, or software developer. It doesn’t mean that you’ll automatically become one as soon as you leave school, but it does give you a foundation for subsequent learning and application of those skills. The advantage of a good college is that the skills they imbibe (one of the strongest of which being critical, logical thinking) are a bit broader than a trade school or technical institute, but even that has its limits.
Anyhow, as a result of its heterogeneity, human capital is specific and complementary. I just focused on some of the specificity angle above: spending four or more years in a college should ideally help develop a particular set of tools, including some general tools, as well as some “tools of the trade” in the relevant major. The end result is that you develop certain skills which help you to provide value to others.
These skills are complementary, as well. The value of an individual software developer, industrial engineer, architect, economist, psychologist, historian, teacher, or other college-educated individual depends, in large part, on everybody else out in the broader market. My ability to make databases purr means more in a world in which I can work with developers who do exciting things with code, business analysts who figure out exactly what people want, and end users who use our applications to make their lives better. It also depends on a whole host of other people who provide their services in our big catallaxy. If every single person were trained solely as a software developer, we would lose a lot of complementarities of human capital. A functioning catallaxy requires more than just software developers, and market signals help us learn this by raising the relative wages of different professions.
But sometimes, those in positions of authority ignore those market signals and decide that they know better—thus, the insistence that people who do not attend college are failures. Unfortunately, this has long-term consequences, and ones which economists who do not take Ludwig Lachmann seriously could not foresee. It’s a shame that consequences have the same power regardless of intention…