In mathematical logic, a theory is the deductive closure of a set of axioms (that is, the set of all propositions deducible from a set of axioms). In the early- and mid- twentieth century, philosophers of science, under the influence of Bertrand Russell's work in philosophy of language and philosophy of mathematics, attempted rationally to reconstruct scientific knowledge by representing scientific theories with the powerful conceptual tools provided by the theory of formal languages.

The Syntactic View of Theories

The syntactic view of theories (also called the received view) was developed by Rudolf Carnap, Ernest Nagel, Hans Reichenbach, and other logical empiricists. Like David Hume, these philosophers thought that insofar as scientific theories accurately describe the world, they cannot be known a priori, but they also recognized that some elements of our theoretical knowledge seem to be independent of the empirical facts...