Mereological essentialism , composition , and stuff : a reply to Kristie

In ‘Essential stuff’ (2008) and ‘Stuff’ (2009), Kristie Miller argues that two generally accepted theses, often formulated as follows, are incompatible: (Temporal) mereological essentialism for stuff (or matter), the thesis that any portion of stuff has the same parts at every time it exists. Stuff composition, the thesis that for any two portions of stuff, there exists a portion of stuff that is their mereological sum (or fusion). She does this by considering competing hypotheses about stuff, trying to prove inconsistency in all cases and with all corresponding understandings of mereological essentialism and stuff composition. I explain why, from an endurantist standpoint, her argument does not go through. Introduction In recent work (2008, 2009), Kristie Miller considers two theses, which are often characterized in the following manner: (Temporal) mereological essentialism for stuff (or matter), the thesis that any portion of stuff has the same parts at every time it exists. Stuff composition, the thesis that for any two portions of stuff, there exists a portion of stuff that is their mereological sum (or fusion). She argues that these two generally accepted principles are incompatible, and that, given the plausibility of stuff composition, we should conclude that mereological essentialism for stuff is false. She does this by considering competing hypotheses about stuff. She attempts to establish incompatibility in all possible cases, in particular whether one is a perdurantist or an endurantist. Her argument is also meant to apply independently of one’s preferred semantics for mass nouns (e.g. a semantics based on mereology or plural reference) and one’s corresponding understandings and formulations of mereological essentialism and stuff composition. The details of Miller’s demonstration vary with the alternative conceptions of stuff she considers. But at heart, the basic set-up of her argument remains the 1 Institut Jean Nicod (ENS-EHESS-CNRS), [email protected] 2 This could also be called ‘mereological constancy’, in order to distinguish it from the stronger claim that any portion of stuff has the same parts at every time it exists, in every world in which it exists. 3 Cf. Zimmerman (1995) and Markosian (2004).