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Persistence Through Time

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Author:: Sally Haslanger

Tags:: Metaphysics Philosophy Time

1. The Puzzle(s)

We know good and damned well that things change, but careful inspection of these things, and their changes, tend to be, well, puzzling.

If we think of a candle, that's 5 in tall, and is left lit, and then dies out at 1in tall, we know that the original candle, and the resulting candle are not the same: a single object can't possess a property that is immediately contradictory of itself- so there must be two unique candles.

Unless that object is extremely small (see uncertainty).

The first type of counting we became familiar with as a species was done on hands, with shells, and rocks. It was binary, leading us to indicate the existence of something as 'existent (1)', or 'non-existent (0). QM, however, allows for something to possess, or rather, be, in both states simultaneously.

However, this isn't a realistic explanation, because the candle didn't go from 5 to 1 in, immediately. This was a gradual process, effectively crossing the entire range of the real numbers contained in the interval (5,1)\small (5, 1).

The core of this issue is the concept of alteration, or change in the property of some object: the property is different after the change, than it was prior.

If we assume that the passage of time involves change, and objects cannot possess incompatible properties, then the different properties, observed, belong to different objects: this brings about the paradox of no object being able to persist through time, which is the logical conclusion, but completely incorrect with regards to our conscious experience.

Principles Underlying The Paradox

1.) Persistence Condition: Objects, such as a candle, or a tree, persist through change.

2.) Incompatibility Condition: The properties involved in a change are incompatible.

3.) Law of Non-contradiction: Nothing can have incompatible properties.

The law of the excluded middle is a law of classical logic, claiming that only one statement from AA and ¬A\neg A is necessarily true, and that the other is necessarily false.

This alone does not bring us to paradox, but the addition of two more features of alteration will.

4.) Identity Condition: If an object persists through the change, the objects on either side of the change, are the same object.

5.) Proper subject condition: The object being altered is the proper subject of the proper subject of the properties involved in the change.

This leads us to the following options for resolving this paradox, listed with respect to the aforementioned principles that they challenge:

Objects do not persist through change.

The properties involved in the change are actually compatible.

Objects can have incompatible properties.

An object may persist, without continuing to exist.

An object undergoing change, is not the proper subject of the incompatible properties involved in the change.

2. Persistence: Perdurance, Endurance, and Exdurance

While it is possible to take the position that nothing persists through time, this flies in the face in the way we perceive and interact with the world.

The controversy lies in trying to figure out what the precise requirements for an object to persist are.

Two prominent concepts for the nature of persistence have been developed recently, endurance, and perdurance.

Persistence via endurance requires an object to be wholly present at different times.

Persistence via perdurance is a bit more complicated, but helps to clarify the meaning of "wholly present" with regards to endurant persistence: an object persists by perduring if it has a part existent at time t\small t, and another part existent at time t+n\small t + n.

In this perspective, an objects persistence through time, is similar to an objects existence in space: the candle is not wholly present at each spatial region is occupies, but is "partially present" at each different region.

The object that persists via perdurance, has temporal parts, or stages, that only briefly exist, with distinct stages being the proper subjects of properties that are incompatible, and the temporal composite that is represented by these parts, or stages, is the persisting subject.

The persisting object does not change by gaining or losing any degree of its properties, but rather in the way that the color of an image is different at various locations.

The solution here is that the proper subject condition has been modified: the persisting object is no longer the proper subject of the incompatible properties it displays, but rather the proper subjects of the incompatible properties are

Referenced in

Persistence Through Time