Aristotelian supervenience

Three matchsticks could be arranged on a table so as to form a triangle. Were you to place a lump of sugar into a cup of hot tea it would dissolve. You might never have been born. Such assertions express modal judgements and, as we suppose, truths about the universe. But if modal judgements can be true, what features of the universe make them true? Thanks largely to the efforts of David Lewis, philosophers nowadays find it natural to appeal to alternative worlds to explicate modality. Something is possible if it occurs in at least one alternative world. A subjunctive conditional is true if, in the nearest worlds in which its antecedent is true, its consequent is true. This paper includes a discussion of Lewis s Humean ontology, the role alternative worlds play in Lewis s account of modality, and an Aristotelian alternative.