In my article '"New Political Economies" Then and Now: Economic Theory and the Mutation of Political Doctrine', Amer. Journ. of Econ. and Soc. 61.1 (2002): 13-51, I attempted to show how purely internal developments in economic analysis from c. 1870 - 1930 gradually undermined the theoretical basis of laissez-faire and predisposed most economists to collectivism by the Second World War. The article is reprinted as Chap 14 in my recent book (2004). If I may add a comment to this discussion: I do not think 'ideology' has very much to do with it. Economists trying to understand how the system works believed -- during the period I refer to here -- that they were discovering, by politically neutral scholarly inquiry, that many of the political-economic doctrines they had assimilated as young men from their elders were scientifically defective. Anthony Waterman