This dissertation addresses a contentious topic within the history of political economy and the interpretation of several influential theories which engage with it. It is what I call the “problem of overproduction or underconsumption” (POU), which is intimately related to involuntary unemployment. The orthodox, classical theory of political economy (i.e., Adam Smith, Jean Baptiste Say, and David Ricardo), I argue, can neither recognize nor explain the POU as an actual problem, because its fundamental assumptions rule out the very possibility of the POU a priori (e.g., Say’s Law). Indeed, Smith implicitly and Say and Ricardo explicitly state that the POU is impossible. In his philosophical discussion of modern poverty and the “rabble” (Pöbel), G.W.F. Hegel, meanwhile, recognizes the possibility of the POU, because he recognizes it as something that actually happens in modern society. And, interestingly, he also seems to suggest that it is the cause of involuntary unemployment and the “rabble”. Because he is still steeped in the assumptions of the orthodox, classical theory, however, he cannot fundamentally or sufficiently explain it. In his Capital, Karl Marx ultimately presents alternative assumptions with which the POU and involuntary unemployment can be recognized and explained. They are his novel concepts of value and capital. His theory of the dynamic of capital investment presents one possible explanation of what he calls the “surplus population” or “industrial reserve army” of the unemployed, which is arguably just what Hegel means by the “rabble”. The payoff, as it were, of the research presented here is threefold: first, a view according to which Hegel’s phenomenon can arguably be saved; second, a philosophical analysis of the limits of orthodox, classical political economy; and finally, a novel interpretation of Marx’s economic theory of capitalist societies, according to which it is closer to the post-Keynesian school of macroeconomics than the orthodox, classical school or David Ricardo (“labor theory of value”).