Dualities and intertheoretic relations

This paper is concerned with the significance of physical dualities from the viewpoint of philosophy of science. The idea is that, for its peculiarity, this ‘new’ ingredient in theory construction can open unexpected perspectives for the current philosophical reflection on contemporary physics. In particular, dualities represent an unusual type of intertheory relation, the meaning of which deserves to be investi gated. It is the aim of the paper to show how discussing this point brings into play, at the same time, discussing what is intended by a ‘theory’ and in which sense dualities are to be considered ‘symmetries’. These issues are addressed by focussing, in particular, on the first form of duality explicitly applied in twentieth century physics, that is electromagnetic duality.