title: Pluto and the platypus: An odd ball and an odd duck - On classificatory norms.
abstract: Many astronomers seem to believe that we have discovered that Pluto is not a planet. I contest this assessment. Recent discoveries of trans-Neptunian Pluto-sized objects do not militate for Pluto's expulsion from the planets unless we have prior reason for not simply counting these newly-discovered objects among the planets. I argue that this classificatory controversy - which I compare to the controversy about the classification of the platypus - illustrates how our classificatory practices are laden with normative commitments of a distinctive kind. I conclude with a discussion of the relevance of such "norm-ladenness" to other controversies in the metaphysics of classification, such as the monism/pluralism debate.
authors.affiliation: Bucknell University, One Dent Drive, Lewisburg, PA 17837, USA. Electronic address: matthew.slater@gmail.com.
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Slater
keywords: Classification; Norms; Platypus; Pluralism; Pluto