No John Maynard Keynes? That definitely seems like an enormous divergence! On the other hand, if I am not mistaken I think other economists were reaching conclusions similar to Keynes around the same time or shortly before, though I am fairly sure that nobody had as well developed a theory as that of J. M. Keynes. Even so, it seems almost inevitable that someone IATL would develop an economic theory identical or very similar to Keynesian economics, largely in reaction to the global depressions of the 1920's and 1930's. Sooner or later someone would critique capitalism as it operated, calling for a more active role of the government in regulating the economy.