Hesse’s description of models will serve us as an example of a view of theories that is an alternative to the view described by Feigl. However, you will need to watch for the differences between their views since Hesse is not concerned to emphasize them. Like Feigl, she describes theories as hypotheses; and, when she distinguishes her view of science from an alternative view, that view sounds more like the Baconian inductivism than the views of the people—such as Carnap, Hempel, and Reichenbach—who Feigl considers. And, like Feigl, the first person Hesse mentions is the English physicist N. R. Campbell (1880-1949), who was an important source both views of theories. To see the features of Hesse’s view that are different from the view Feigl’s describes, watch for her references to “models,” “analogies,” and “pointers” and imagine someone saying what Hesse never quite does, that theories are models.

Hesse’s paper falls into three main parts, a general introductory discussion in §1, a discussion of examples of theorizing in 19th century physics in §§2-5, and a concluing discussion in §6 where she provides a “partial definition” of the idea of a model. While we are likely to concentrate on the first and last sections, the examples she presents in the others are important for seeing what Hesse has in mind in her more abstract discussions. (Section 3 includes some fairly imposing equations of a sort you may never have encountered, but the points Hesse is making, especially about the equations on p. 208, require only that you notice similarities and differences in the ways formulas appear on the page.)