  But Duhem broadens the critique of model building to include mathematical models along with mechanical models. He decides that, for an English scientist, theory is “for him neither an explanation nor a rational classification of physical laws, but a model of these laws, a model not built for the satisfying of reason but for the pleasure of the imagination” (1914, 117; 1954, 81). The complaint is clear: model building has no real place in physical theory (beyond a minor heuristic role); it can neither be grounded in realism, in the thought that physical theories are explanatory structures, nor in instrumentalism, in the thought that physical theories are classificatory or representative structures. In fact, model building is not even connected to the higher intellectual faculty of reason but to the lower faculty of imagination. So, ultimately, Duhem’s attack on model building is rooted in something more fundamental than his instrumentalist methodology for the physical sciences.