Published online by Cambridge University Press: 01 January 2022
In the social sciences we hardly can create laboratory conditions, we only can try to find out which kinds of experiments Nature has carried out. Knowledge about Nature's designs can be used to infer conditions for reliable predictions. This problem was explicitly dealt with in Haavelmo's (1944) discussion of autonomous relationships, Friedman's (1953) as-if methodology, and Simon's (1961) discussions of nearly-decomposable systems. All three accounts take Marshallian partitioning as starting point, however not with a sharp ceteris paribus razor but with the blunt knife of negligibility assumptions. As will be shown, in each account reflection on which influences are negligible, for what phenomena and for how long, played a central role.
Part of this research for this paper was conducted while the author was a fellow of the Netherlands Institute for Advanced Study, during 2001–2002. Their support is gratefully acknowledged. This paper was presented at the workshop “Measurement in Economics and Natural Sciences,” 13–16 May 2002, at Amsterdam. I thank my two discussants James Woodward and Hasok Chang and the other participants for their helpful comments. I am grateful to the two anonymous referees who provided constructive suggestions.