So why don't we teach much economic history anymore? An article in the Chronicle by Russell Jacoby asks this question, with similar for the history of psychology and philosophy, by wondering why Marx doesn't feature on your typical economics syllabus.
The analogy is probably to the natural sciences. Once we scientificize (is that a word?) economics, it becomes more reasonable to follow the path of the naturals - after all, the history of chemistry, for example, might be interesting, but it doesn't necessarily help you be a better chemist. Economists try to answer very specific, answerable questions: methodology becomes crucial, and while the foundation of methodology is important, it's not it. Here's what Jacoby says on the topic:
The flight from history marks economics and philosophy as well. Economics looks more and more like mathematics, in which the past vanishes. Sometimes it even looks like biopsychology. A recent issue of the American Economic Review includes numerous papers under the rubrics of "Neuroscientific Foundations of Economic Decision-Making" and "Cognitive Neuroscientific Foundations of Economic Behavior." But can we really figure out today's economic problems without considering whence they came?
Of course, my prejudice is the history of thought for its own sake is worthwhile. I want to know how economics evolved; how the foundations of the subject and a couple hundred years of thought brought us to where we are today. However: it's useful like that more to people like me with a predisposition to wonder about the philosophy of the subject than it is to those who are more interested in learning the tools to form and evaluate policy, for example. If I want to advise on school vouchers, to pluck one example, it doesn't necessarily help me to know the history of economic thought; I need to know the evidence on school vouchers. Obviously.
The 'economics as toolbox for analysis' - positivist, scientific economics - maybe doesn't need the past. Research building on research, like we do as academic economists, doesn't need the foundation of the history of thought. Seeing the evolution of the subject, and the little battles over the big issues of days gone by, might, however, make studying the subject as an undergraduate more interesting. Perhaps we could have both: the toolbox-y courses and the intellectual history, for-their-own-sake courses. Why do we need to justify the history only as something that contributes to the toolbox, especially when that might not even be true?
Maybe that's why courses in economic history or the history of economic thought are not as widely offered as you might expect. Maybe they'd be nice or interesting, but very few academic economists are historians or scholars of thought; we're scientists now. What faculty wants to teach a course so wildly unrelated to their other work, their research?