An examination of the foundations of contemporary theoretical economics. Applying concepts from model theory - formal semantics - and standard tools in foundations research the author aims three targets, namely, a characterization of the notion 'empirical economic theory', the determination of the epistemological and methodological status of an important class of 'non-empirical' theories in economics, and the proposal of a taxonomy of economic theories based upon intended epistemological status and the descriptive or operative function of a theory.