In Search ofan Ontology forQuantum Field TheoryDissertationzur Erlangung der Doktorwurde,dem Promotionsausschu Dr. phil.der Universit at Bremenvorgelegt vonMeinard KuhlmannBremen, den 6. Juni 2000ContentsPreface 4List of Abbreviations 6I Introduction 7II Context, Methods and Presuppositions 151 Philosophical Background 161.1 The Development of Atomism in the History of Philosophy . 181.2 Philosophical Versus Scienti c Atomism . . . . . . . . . . . 231.3 Atomism and Reductionism . . . . . . . . . . . . . . . . . . 242 Ontology and Physics 272.1 \On What There Is": Notions of Ontology . . . . . . . . . . 272.2 The Analytical Tradition of Ontology . . . . . . . . . . . . . 302.3 Excursion: No-Go Theorems in Quantum Physics . . . . . . 323 Fundamentals of Quantum Physics 353.1 The Legacy of Quantum Mechanics . . . . . . . . . . . . . . 353.2 The Standard Formalism of QFT and its Problems . . . . . 403.3 The Relation of QFT and AQFT . . . . . . . . . . . . . . . 433.4 Basic Ideas of AQFT . . . . . . . . . . . . . . . . . . . . . . 451CONTENTS 24 (A)QFT as Objects of Philosophy 484.1 Quantum Mechanics versus QFT . . . . . . . . . . . . . . . 484.2 QFT versus Algebraic QFT . . . . . . . . . . . . . . . . . . 524.3 The Philosophical Interest in (A)QFT . . . . . . . . . . . . 56III Classical Ontologies 595 Classical vs. Revisionary Ontologies 605.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . 615.