Towards an Ontology for Quantum Field Theory

The recent work of P. Teller and S. Auyang in the philosophy of Quantum Field Theory (QFT) has stimulated the search for the fundamental entities of that theory. In QFT, the classical notion of a particle collapses. The theory does not only forbid classical, i.e. spatiotemporally identifiable particles, but it makes particles of the same type conceptually indistinguishable. Teller and Auyang have suggested competing ersatz-ontologies which could account for the (loss of the particles(: Field quanta vs. Field events. However, both ontologies suffer from serious defects. While quanta lack numerical identity, spatiotemporal localizability, and independence from basis-representations, events-if understood as concrete measurement events-are related to the theory only statistically. I propose an alternative solution: The entities of QFT are events of the type (Quantum system S is in quantum state ((. The latter are not point events, but Davidsonian events, i.e. they can be identified by their location inside the causal net of the world. 1.Preface In recent analytical work on ontology, ontological problems raised by modern physics are mentioned casually at most. This corresponds to a widespread neglect of analytic ontology by people studying the ontological consequences that follow from physics theories, e.g., from Quantum Field Theory. In this paper I shall argue that, despite the spirit of mutual disregard of ontology and physics, exchange of ideas between those fields can be beneficial. Some of the moves in the development of pure ontological conceptions do seem to address the ontological problems that arise in physics theories. Ontological conceptions, such as the ones developed by interpreted as (responding(to problems of ontology discussed in the recent work on QFT by P.