Rostow's model is one of the more structuralist models of economic growth, particularly in comparison with the "backwardness" model developed by Alexander Gerschenkron, although the two models are not mutually exclusive. Rostow argued that economic take-off must initially be led by a few individual economic sectors. This belief echoes David Ricardo's comparative advantage thesis and criticizes Marxist revolutionaries' push for economic self-reliance in that it pushes for the "initial" development of only one or two sectors over the development of all sectors equally. This became one of the important concepts in the theory of modernization in social evolutionism.