A Lewisian Interpretation of Logical Consequence

David Lewis was a reductivist and nominalist. He saw the majority of his philosophical works to be a campaign on behalf of Humean Supervenience; a doctrine according to which the distribution of perfectly natural properties (/relations) acts as a supervenience basis for all contingent truths; such as causation, counterfactuals, events, and laws. He also extends his reductivism to the domain of a necessary discourse like mathematics by trying to reconstruct second-order ZFC through mereology. A domain that he never addressed, though, was logic. The purpose of this article is to present a Lewisian interpretation of logic which similar to his own interpretation of mathematics, is based on mereology. On this interpretation, the relation of logical consequence is reduced to a mereological relation between singletons of possible worlds. Furthermore, the implications of this interpretation for the two main characteristics of logical consequence, i.e. necessity and formality, and also the consistency and completeness of logic are examined.