What Is a Scientific Theory?

In this chapter I first present the objectifying attitude, which is characteristic of science, in contrast with the holistic attitude, which is specific to art, friendship and religion. Then, I define models as structures of properties organised by relations, such as nomological formulas like PV=KT. I explain how models can represent scientific objects, namely systems of properties, by endorsing a structural view of representation. According to the model-theoretic view of theories, these are classes of models, whereas for the syntactic view, theories are sets of propositions. I advocate what I call a “synthetic view” according to which theories are constituted of both propositions and models. Models perform a dual role: they can represent objects and also make true some propositions, among which scientific laws. Since scientific theories are supposed to explain phenomena, I contend that the explanatory power of a theory relies on mechanistic models which make causal laws true. A causal law is defined in a syntactic way as a universal proposition which contains a time derivative (or something equivalent to it), which refers to the effect whereas the other terms refer to the cause. Finally, I briefly discuss the issue of determinism.