Published online by Cambridge University Press: 01 January 2022
This article introduces and motivates the notion of a “properly extensive” quantity by means of a puzzle about the reliability of certain canonical length measurements. An account of these measurements’ success, I argue, requires a modally robust connection between quantitative structure and mereology that is not mediated by the dynamics and is stronger than the constraints imposed by “mere additivity.” I outline what it means to say that length is not just extensive but properly so and then briefly sketch an application of proper extensiveness to the project of providing a reductive ground for metric quantitative structure.
I am indebted to Erica Shumener, Harjit Bhogal, Shamik Dasgupta, Hartry Field, Cian Dorr, Tim Maudlin, audiences at the BSPS and PSA 2014 meetings, and the NYU Thesis Prep seminar for invaluable comments on previous versions of this article.