Abstract

Any author should be happy when commentators on a long book discuss it thoroughly, raise important issues, and show their sensitivity to its main themes. So I want to begin with thanks to Isaac Levi, Peter Machamer, Richard Miller and Dudley Shapere. This is not, of course, to register agreement with all their criticisms. Indeed, that would be impossible, for their perspectives are so varied as to resist integration into a consistent synthesis. Nevertheless, each of them poses problems that my approach to the growth of scientific knowledge must address, and I believe that the combination of their essays greatly advances the discussion.