9 Endurance
The question remains how best to understand endurance, which (Lewis 1986) characterized as follows:
To endure is to be wholly present at more than one time within a certain interval.
We have discarded mereological interpretations of being wholly present in terms of the relation of part to whole, but this is not to say that the phrase is unintelligible. (Fine 2006) suggests it is a mistake to attempt to characterize it in more basic terms. Instead, he invites us to draw a basic distinction between two different forms of presence: existence and extension.
9.1 Two Modes of Presence: Existence and Extension
Material objects are present both in spatial regions and at times and time intervals. But (Fine 2006) draws a crucial distinction between the way in which objects are present at times and time intervals and the way in which they are present across regions of space:
Material objects exist at different times and time intervals but not by virtue of their presence at other times or subintervals.
Material objects extend through regions of space by virtue of their presence in the relevant subregions.
According to (Fine 2006), the best we can do is to offer an elucidation of existence in terms of a contrast between partial and entire presence. Here is how the contrast plays out in the case of spatial presence:
When an object extends, or is located at, a given place, then it may either be located in its entirety or in part at that place. A chair, for example, will be located in its entirety at the region occupied by the chair but will only be located in part at the region occupied by the back of the chair.
Matters are different for temporal presence:
[T]his is not how it is for existence. The point is usually put by saying that, for the 3D-er, a thing will exist, or be present, in its entirety at a given time. But this is somewhat misleading. […] The better way to make the point is that, whereas we can meaningfully distinguish between an object’s being located in its entirety or in part at a given place, we cannot meaningfully distinguish in the analogous way between an object’s existing in its entirety or in part at a given time. Location may be a matter or more or less but existence is not.
This may suggest a partial reformulation of endurance in terms of existence:
To endure is to exist at more than one time within a certain time interval. That is, to endure is to be present at more than one time within a time interval in a mode for which the partial/entire distinction does not make sense.
The distinction comes at a cost. For unlike the perdurantist, the endurantist appears to make presence a disjunctive concept. So, some philosophers may simply reject to take a distinction on board on the grounds that there is only one intelligible and comprehensive mode of presence: extension. Material objects are present in time much like they are present in space, which means that they persist by virtue of having temporal parts at each time interval at which they are present.
9.2 Linguistic Evidence for the Distinction
(Fine 2006) argues that the distinction is embedded in ordinary language. Consider the locative use of the word ‘is’?
| Objects | Events | |
|---|---|---|
| Time | When is Peter? ✗ | When is the Party? ✓ |
| Space | Where is Peter? ✓ | Where is the Party? ✓ |
What explains the fact that I cannot properly ask ‘When is Peter?’? One suggestion is that the locative use of ‘is’ patterns after extension. Both objects and events extend through space, but only events extend through time. Because objects like Peter do not extend through time, we have no means to make sense of the question ‘When is Peter?’.
There is a similar observation for ‘exists’:
| Objects | Events | |
|---|---|---|
| Time | When did Plato exist? ✓ | When did the Party exist? ✗ |
| Space | Where did Plato exist? ✗ | Where did the Party exist? ✗ |
Unlike the locative use of ‘is’, the locative use of ‘exists’ appears to pattern after existence. Only objects exist at times, events extend through time. Furthermore, neither objects nor events exist in regions of space, they extend through them.
One last piece of linguistic evidence involves the use of ‘motion’:
| Objects | Events |
|---|---|
| A billiard ball is in motion ✓ | The movement of the billiard ball is in motion ✗ |
How should we explain the difference when both the billiard ball and the movement of the billiard ball are subject to the same variation of position over time. The three-dimensionalist may now reply that genuine motion requires a change in position for something that is entirely present at each moment of the change. So, only objects that exist at different times are subject to genuine motion.
9.3 Parts and Wholes
Compare the conditions under which composite objects and events are present at a given time and place.
We begin with the case of material objects. On the one hand, composite objects are present at a time only if all of their parts are present at that time. On the other hand, composite events are present at a place only if some of their parts are present at that place.
| Quart of milk Q made out of two pints A and B | Two pints A and B making the quart of milk Q | |
|---|---|---|
| Time | Q is present at a time t | Both A and B are present at a time t |
| Space | Q is present at a place R | Either A or B is present at a place R |
We move on now to events. Consider a lightning event composed of two streaks of lightning. This time around the composite event is present at a time or place just in case either part is present at the time or place.
| Lightning event L composed of two streaks H and I | Two streaks H and I making the lightning event L | |
|---|---|---|
| Time | L is present at a time t | Either H or I are present at a time t |
| Space | L is present at a place R | Either H or I is present at a place R |
Why the difference between composite objects and composite events? The endurantist appears to have a simple answer: material objects, whether composite or not, exist at a time but are extended in space. The conjunctive condition is appropriate for existence, whereas the disjunctive condition is suitable for extension.
Why does existence generate the conjunctive condition? Suppose the presence of a part turned out to be sufficient for the existence of a whole. In that case, existence could be qualified as partial or entire. But since no sense is to be made of partial existence, we cannot require less than the conjunctive condition for the composite object to exist at a time.
9.4 Temporary Parts Revisited
What is for a streak of lightning to be part of a composite lightning event at a given time t? That comes down to the fact that (i) the streak of lightning is an atemporal or nontime-relative part of the composite lightning event and (ii) the streak in question is present at t. On the other hand, to revisit the situation (Thomson 1983) discussed, when we claim that alpha is part of the Lego House at 1:15, we had better not mean that alpha is (i) an atemporal or nontime-relative part of the Lego House, and (ii) alpha is present at 1:15.
The heuristic thought is that for an object to be part of another is for one to be wholly present in the latter, which means that the object must be wholly present at the time at which it is part of the other object. Here is the requirement (Fine 2006) lays out:
When an object is part of another at a given time or place, it should be wholly present at that time or place.