Preface Part I. Introduction Section 1 Generic definitions and basic modal realism Section 2 Metaphysical versus logical possibility? Section 3 S5 Section 4 Eight views of possibility Part II. Applications and pseudo-applications Section 1 Modality Section 2 Counterfactuals and causality Section 3 Propositions Section 4 Properties Section 5 Overall assessment Part III. The Lewisian ontology of extreme modal realism Section 1 The Lewisian account of possible worlds Section 2 Identity vs. counterpart theory Section 3 Indiscernible worlds? Section 4 Lewis's arguments for his ontology Section 5 Objections to Lewis's account of actuality Section 6 The possibility of spatio-temporally unrelated co-actual entities Section 7 Cardinality and the "set" of all possible worlds Section 8 Ethical issues Section 9 Induction and actuality Section 10 The epistemological objection Section 11 Explaining the actual in terms of the necessary Section 12 A final assessment of extreme modal realism Part IV. Platonic ersatz ontologies Section 1 The general strategy Section 2 Linguistic approaches Section 3 Platonism Section 4 Conclusions Part V. Sketches towards a Spinozistic-Tractarian account of modality Section 1 Asserting, naming and infallibility Section 2 Spinoza Section 3 A radical theory of modality Section 4 Costs Section 5 The less radical theory Part VI. Aristotelian-Leibnizian ontology Section 1 Leibniz's approach Section 2 Aristotelian possibility and causality Section 3 Combining with the Spinozistic-Tractarian view Section 4 Ordinary alethic modal talk Section 5 The Principle of Sufficient Reason Section 6 Ontology and implications Section 7 The main challenges to Lewisian and Platonic ontologies can be resolved Section 9 Objections to the A-L view Part VII.

Final conclusions Section 1 Cost-benefit arguments for the Aristotelian-Leibnizian ontology of possible worlds Section 2 Choosing between accounts of possibility Bibliography.