I find methodological inquiry interesting and instructive to the extent to which it addresses itself to concrete problems of empirical science. Thus, while I find myself in general agreement with almost everything that has been said in the previous papers and by discussants, I should like to pitch my remarks at a level less abstract than theirs.

The Relation of Premises and Conclusions in Economic Theory

Professor Nagel has pointed out that whether a particular proposition is a fundamental assumption of a theory or one of its derived conclusions is relative to the formulation of the theory. If this were the whole story, then asymmetry between assumptions and derivations in Friedman's position – what Professor Samuelson called the F-Twist, and what I like to think of as Friedman's “principle of unreality” – would be entirely arbitrary. Professor Krupp's remarks on composition laws and the relation of microscopic to macroscopic theories suggest, however, that something more is at issue.