Mereological endurantism defined

ABSTRACT

I develop a definition of mereological endurantism which overcomes objections that have been proposed in the literature and thereby avoids the charge of obscurity put forward by Sider against the view.

KEYWORDS:

• Three-dimensionalism
• wholly present
• mereology
• persistence
• time

Acknowledgements

I would like to thank Claudio Calosi, Cody Gilmore, Alessandro Giordani, Matt Leonard, Kevin Mulligan, Benjamin Neeser, Thomas Sattig, audiences in Padua and Milan as well as an anonymous referee for their useful comments on earlier drafts of this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Presentists might be an exception here. More on this later.

2 On closer look, a part of it is also redundant. Given what we have said before, insofar as nothing can be part of something at a time without existing at that time, (ii) implies (i).

3 Sider considers a modal variant of this definition, which has the drawback of placing the dispute between three- and four-dimensionalism in the realm of modality. The dispute is about ‘what objects actually do, not what they are capable of doing’ (Sider 2001, 67). The conception of whole presence that I put forward in the next section is not modal in nature.

4 I am here assuming a notion of temporary parthood whereby a temporary part is such that it is entirely located at the relevant time – x <_t y → x@_<t – where an entire location of x is conceived of as a region which has an exact location of x as a part – x@_<r := ∃s (x@s ∧ s < r (Casati and Varzi 1999). To illustrate, under such an understanding, a perdurantist would say that the current temporal part of my left hand is a part now of me, whereas my left hand as a perduring entity is not a part now of me, for it is not entirely located at the present instant (but of course it is a part of me at the interval of my persistence, or at a time which is an entire location of my left hand). If this is not a reader’s notion of temporary parthood, she can add a clause to the effect that the proper temporary parts under consideration must also be entirely located at the relevant time. One might wonder whether adopting a primitively temporary notion of part is at odds with recently developed locative approaches to mereology, according to which x is part of y iff the exact location of x is a sub-region of the exact location of y (Markosian 2014). I thank an anonymous referee of this journal for raising this point. Regardless of whether the sub-region relation is cashed out in mereological terms (Gilmore and Leonard 2020), set-theoretic terms (Calosi, forth), or otherwise, one wonders whether that relation will need to be relativized as well. However, a full assessment of the compatibility of temporary parthood and locative approaches to mereology goes beyond the scope of this paper.

5 For those who are wondering whether proper temporal parts are parts of objects at times, and whether we should not instead say that they are parts of objects simpliciter, I refer to Sider instructions on how to define temporary parthood in terms of timeless parthood (Sider 2001, 57) or on how to define temporal parts in terms of a primitive notion of temporary parthood (Sider 2001, 59).

6 For an overview of classic views of this kind, see Rea (1995); for an overview of recent neo-Aristotelian versions, see Baily and Wilkins (2018). Notice that among contemporary neo-aristotelians Fine’s theory of embodiment fits the bill. While Koslicki’s (2008, 2018) does not. Under the former, the formal component does not constitute the substance in the same way as the material constituent does, but rather ‘retains its predicative role’ (Fine 1999, 66). Under the latter, substances, even though hylomorphic, are identical with mereological sums (of the material and the formal constituent).