 The first extended reflections on economic methodology appear in the work of Nassau Senior (1836) and John Stuart Mill (1836). Their essays must be understood against the background of both the economic theory and the philosophy of science of their times. Like Smith’s economics (to which it owed a great deal) and modern economics, the “classical” economics of the middle decades of the 19th century traced economic regularities to the choices of individuals facing social and natural constraints. But, as compared to Smith, more reliance was placed on severely simplified models. David Ricardo’s Principles of Political Economy (1817), draws a portrait in which wages above the subsistence level lead to increases in the population, which in turn require more intensive agriculture or cultivation of inferior land. The extension of cultivation leads to lower profits and higher rents; and the whole tale of economic development leads to a gloomy stationary state in which profits are too low to command any net investment, wages slide back to subsistence levels, and only the landlords are affluent.