1. Lecture 11 Persistence: arguments for perdurance
Dr. Donnchadh O’Conaill
28/2/2017
Metaphysics University of Helsinki

2. 1. Introduction Persistence: existing through time
Different theories of persistence: endurance vs perdurance
Endurance is the commonsense view:
I wholly and completely exist during this lecture, rather than just part of me being here at this time
Endurance has other advantages:
Theoretical parsimony
Avoids certain theoretical problems

3. Perdurantist response: perdurance fits better with phsyics (e. g
Perdurantist response: perdurance fits better with phsyics (e.g., relativity theory)
Perdurance actually closer to commonsense than endurance:
“there are insuperable logical difficulties in the assumption that we have numerical identity where we have persistence through change” (Loux 2006, 243)
Will examine two ways of developing this argument

4. 2. Change in intrinsic properties
Intrinsic properties: properties which an entity has independently of any other entities: e.g., shape, size
vs extrinsic properties: e.g., being married
“Persisting things change their intrinsic properties. For instance, shape: when I sit, I have a bent shape; when I stand, I have a straightened shape. Both shapes are temporary intrinsic properties; I have them only some of the time. How is such change possible?” (Lewis 1986, )

5. Indiscernibility of Identicals: necessarily, for entities A and B, if A = B, F is a property of A if and only if F is a property of B
plausibly, this applies to intrinsic properties
Problem: if I have (at time t) a property of having a bent shape, and then at t+1 a property of having a straight shape, how can I be identical at both times?
Perdurantist: me-at-t is numerically distinct to me-at-t+1 (i.e., they are different temporal parts) – so no problem

6. Endurantist response 1
Rather than speaking of ‘having a bent shape’ and ‘having a straight shape’, refer to temporally indexed properties:
e.g., I don’t have property of having a bent shape at t, but rather I have property of having-a-bent-shape-at-t
I do not have this property only at t: rather, this is a timeless attribution, if I ever have this property then I always have it
So there is no property which I have at t but not at t+1

7. Problem: this makes intrinsic properties “disguised relations, which an enduring thing may bear to times” (Lewis 1986, 204)
Furthermore, it seems to rule out an entity’s gaining or losing properties, which is what some changes seems to consist in
Compare change on this view with Russell’s view of change which McTaggart criticises: this view doesn’t even allow for variation in properties across times

8. Endurantist response 2: presentism
Don’t appeal to time-indexed properties, but to limits on when an entity can have a property
i.e., “tensed notion of having a property” Loux, 246
Presentist: to attribute property F to entity A is to say that when A is present, it is F
In Indiscernibilty of Identicals, F is a property of A only if it is a property of B
but if presentism is correct, F is a property of A only if A has F now

9. So I cannot both have a bent shape and have a straight shape – when t is present, I will have the first property but not the second, and when t+1 is present, I will have the second but not the first
“it is simply not true that I have the property being straight if I am bent now. I was straight, and will be again; but I am not now, and so there is no problem of my having incompatible intrinsic properties” (Zimmerman 1998, 212)

10. 3. Change in parts
“a thing’s remaining numerically identical through a change in its parts conflicts with a principle which tells us that if a thing, x, and a thing, y, are numerically identical, then every item that is a part of x is a part of y and vice versa” Loux, 248
Descartes prior to t: call him D-before-t
Descartes-minus: Descartes except his left hand
At t, Descartes’ left hand is amputated

11. (1) D-before-t is numerically identical with D-after-t (i. e
(1) D-before-t is numerically identical with D-after-t (i.e., we assume endurantism)
(2) D-minus-after-t is numerically identical with D-minus-before-t
D-minus has not lost any parts or changed any of its intrinsic properties, so why not think it has persisted?
(3) D-after-t is numerically identical with D-minus-after-t
They occupy exactly the same space, have exactly the same parts, etc.

12. Transitivity of identity: if a = b, and b = c, a = c
From (1)-(3) plus transitivity of identity…
(4) D-before-t is numerically identical with D-minus-before-t
But (4) is false: D-before-t has properties (and parts) which D-minus-before-t does not
Perdurantist can deny (4), because they do not accept (1) and (2)
How can the endurantist respond?

13. 4. Endurantist responses: mereological essentialism
Mereological essentialism: whatever parts an entity has, it has them necessarily
Any loss of parts entails that the entity ceases to exist
Reject (1): when Descartes loses his hand, he ceases to exist, is replaced by D-minus
Problem: seems possible for something to survive changes in its parts
Chisholm: in pre-philosophical sense, this is true – but in strict sense, it is false
Compare: ‘The sun rises in the morning’

14. Primary entities: things in the ‘strict and philosophical’ sense, cannot survive the loss of any of their parts
“Our concepts of familiar material objects like desks and chairs, however, are not concepts of primary entities, but concepts of successions or chains of primary entities” Loux, 252
These secondary entities are identical through loss of parts only in the pre- philosophical sense

15. Relative identity No notion of identity which applies to everything:
x is identical with y only relative to a specific kind of thing to which each belongs
E.g., ‘same dog’, ‘same animal’
But x could be distinct from y relative to a different kind of thing
Say Tommy is a dog a t1, and is transformed into a cat at t2
Tommy is the same animal at t1 and t2
Tommy is not the same dog at t1 and t2

16. Transitivity of identity: if a = b, and b = c, a = c
This true only within a specific kind – does not hold across kinds
This lets us reject the move from (1)-(3) to (4): D-minus is not a human, but a human fragment, i.e., belongs to a different kind
Problem: this requires giving up a central property of identity, i.e., transitivity across kinds

17. Identity and persistence conditions
Spatially coincidant entities: occupy same region of space, but distinct
E.g., bronze statue and lump of bronze
They are not identical as they have different persistence conditions, e.g., they can survive different changes
Can deny (3): “since D-after-t and D-minus-after-t have different histories, they cannot be identical” (Loux 254)
If Descartes loses his right hand at t+2, D-minus will cease to exist, but Descartes could survive

18. Works cited
David Lewis (1986) ‘Against Overlap’ in On the Plurality of Worlds. Oxford: Oxford University Press.
Dean Zimmerman (1998) ‘Temporary Intrinsics and Presentism’ in Van Inwagen, P. & Zimmerman, D. (eds.) Metaphysics: The Big Questions. Oxford: Blackwell.