Lecture 10 Persistence: endurance and perdurance Dr. Donnchadh O’Conaill (DonnchDH.Oconaill@Helsinki.fi) 23/2/2017 406772 Metaphysics 2016-17 University of Helsinki

1. Introduction: persistence Concrete particulars: things which persist Persistence: existing through time Contrast with entities which do not exist in time (e.g., Platonic universals) Or entities that do not exist through time (e.g., instantaneous events) Typically, can exist through change E.g., I am the same individual as beforeI had my last haircut What metaphysics is required for claims like this to be true?

2. Endurantism vs perdurantism Two different theories of persistence: Endurantism: “for a concrete particular to persist through time is for it to exist wholly and completely at different times” (Loux 2006, 230) Perdurantism: for concrete particular to persist is for it to have different temporal parts at different times Temporal parts: like spatial parts, but located in time rather than space e.g., ‘Maija today’ vs ‘Maija on Friday’

Consider a spatially extended entity, Sara Sara occupies different portions of space, because she has different spatial parts which occupy these different portions Her head occupies one portion of space, her feet another – Sara is present in each portion, but not all of her (just some part) Perdurantist: Maija exists at different times, not because all of her exists at any time, but because some of her temporal parts do

3. Endurantism There are no temporal parts ‘Maija today’ and ‘Maija on Friday’ pick out the same entity Maija exists at each of these times because the whole of Maija exists at each time E.g., when Maija truly says ‘I am here now’, this is true because she is wholly here, not just part of her When I hold an apple, I can hold all of it, not just the part which exists now

Why accept endurantism? “the view that flows out of our pre-philosophical understanding” (Loux 256) Allows us to interpret many commonsense claims as literally true: ‘I am in the room’ (not just a part of me) Theoretical parsimony Avoids certain theoretical problems How does endurantism explain persistence? Arguably, it doesn’t Identity of concrete particulars through time is unproblematic

4. Perdurance “I am a temporal whole made up of all my temporal parts” (Loux 232) i.e., I am a collection of parts, and I exist at different times because my temporal parts exist at different times Many of these temporal parts themselves have temporal parts: e.g., ‘Maija on Friday’ is made up of ‘Maija on Friday morning’, ‘Maija on Friday afternoon’, etc. Each temporal part itself persists by having temporal parts

Each persisting entity is a spacetime worm, a four-dimensional entity with depth in all three spatial dimensions, and also through time The entity can be ‘carved up’ into any number of different temporal parts: ‘Maija on Friday’, ‘on Friday afternoon’, ‘from 12.01 to 12.03 on Friday afternoon’ These parts can overlap, i.e., share parts Some parts might be instantaneous – these could not overlap or persist

Stage theory Possible to believe that there are temporal parts but to deny that ordinary concrete particulars are worms made up of temporal parts “when we talk about the tennis ball with respect to different times, we talk about different stages in that series, and each of these stages is a tennis ball” Hawley 2001, 41 Disagreement with perdurantism is not ontological, but about what we refer to when we say, e.g., ‘the tennis ball’

Which entities persist? Temporal parts do not only make up familiar concrete particulars (tables, persons, etc.) “we can think of temporally smaller items [i.e., temporal parts] as combinable in infinitely many ways” (Loux 239) Consider Bob: the collection of the Eiffel Tower in 1901 and Angela Merkel’s hair from 2001 to 2017 Bob is just as real as me, or the Eiffel Tower: each entity is a collection of smaller temporal parts

“any filled region of spacetime, no matter how gerrymandered, is a material object […] what distinguishes any one of these infinitely many material objects from any other is its location in spacetime” (Loux, 240) Each temporal part belongs to a huge number of different concrete particulars Concrete particulars can and do exist at (partly) the same spatiotemporal location

Problem: why do we accept the Eiffel Tower exists but not Bob? Perdurantist: temporal parts of ordinary entities linked by spatiotemporal continuity, similarities or causal relations Is this satisfactory? Think of a log being burned: the fire is spatiotemporally continuous with the log, they stand in causal relation How similar need the temporal parts be?

Endurantist response Since there are no temporal parts, no need to account for how entities are composed from them No need to posit gerrymandered entities like Bob, or to account for the difference between Bob and the Eiffel Tower Perdurantism rests on two mistakes: identity across time must be analysed Concrete particulars can be understood as collections of concrete particulars

5. Persistence and time B-theory: time is a dimension – this is compatible with concrete particulars being four-dimensional spacetime worms Temporal parts: portion of the worm occupying a region of spacetime Some versions of A-theory (Moving Spotlight, Growing Block) treat time as a fourth dimension Compatible with perdurantism Eternalist not necessarily perdurantist – time might be a dimension, but concrete particulars might be three-dimensional

Presentism: since only what exists now is real, concrete particulars cannot have parts which don’t exist now “the presentist must deny that a thing that exists today can have as parts […] things that existed yesterday, but no longer exist” Loux 235 Does presentism entail endurantsim? Maybe not: why think perdurance requires an entity to have more than one temporal part at any time?

Works cited Katherine Hawley (2001) How Things Persist. Oxford: Oxford University Press.