Philosophers Index Abstract
- Ned Markosian alleges that David Lewis's account of the distinction between persisting by means of temporal parts and persisting without them ('perduring' vs. 'enduring') commits one to 'presentism' – the thesis that the only things that really exist are those that exist now.
- In the first half of this note, Lewis's distinction is defended against this charge.
- In the second half, the doctrine of temporal parts is so formulated as to be consistent with the views of Russell and Broad, who rejected absolutely instantaneous parts.
- The ‘friends of temporal parts’ and their opponents disagree about how things persist through time. … A related dispute pits presentists against non-presentists.
- In order to see the logical relation among the four views in question, one must first recognize how deep the differences are between presentists and non-presentists.
- But does there need to be an improvement?
- Thus, Lewis’s original way of putting the perdurance-endurance1 distinction is, it seems, fine as it stands. However, as Markosian justly notes, the notion of ‘being wholly present’ is in need of further unpacking.
- The ‘friends of temporal parts’ and their opponents disagree about how things persist through time. The former, who hold what is sometimes called a ‘4D’ theory of persistence, typically claim that all objects that last for any period of time are spread out through time in the same way that spatially extended objects are spread out through space — a different part for each region that the object fills. David Lewis calls this manner of persisting ‘perdurance’2. The opposing, ‘3D’ theory has it that at least some objects do not persist in this manner; they ‘endure’ through time by ‘being wholly present at more than one time’.
- A related dispute pits ‘presentists’ against ‘non-presentists’. Presentists hold that the only things that really exist are those that exist now, at the present moment; and nonpresentists believe in something like a ‘block-universe’ in which non-simultaneous objects and events nevertheless co-exist (in a tenseless or non-temporal sense).
- Of late, the relations between these four positions have come under considerable scrutiny. As Ned Markosian3 has pointed out, it would be surprising if commitment to a perdurance4 or endurance theory of persistence automatically foreclosed one’s options in the presentism—non-presentism debate. But, says Markosian, that is just what the standard formulations of the perdurance5 and endurance theories imply. David Lewis has set the terms of the debate; in his usage, someone who thinks that all persisting objects endure would be said to hold the following:
→ (3Da) Any object that exists at different times is wholly present at each moment at which it exists.
While someone who thinks all objects perdure would affirm:
→ (4Da) Any object that exists at different times has different temporal parts at the different moments at which it exists.
Markosian argues that both (3Da) and (4Da) imply the truth of presentism. As alternatives, he offers the following formulations:
→ (3Da) Any object that is present at different times is wholly present at each moment at which it is present.
→ (4Da) Any object that is present at different times has different temporal parts at the different moments at which it is present.
These do not, he claims, imply presentism; and so are preferable to Lewis’s versions. Markosian concludes his paper with a nice explication of what it means to say that an object is ‘wholly present’ at more than one time.
- In this note, I argue that Markosian’s versions are not improvements over Lewis’s; and that the original, Lewis-style statements do not imply presentism. Finally, I offer an alternative account of ‘wholly present’ that makes room for a temporal parts theory according to which there are no instantaneous temporal parts. Before doing any of this, however, we must look at the nature of the presentism—non-presentism debate a bit more closely.
Footnote 3: "Markosian (Ned) - The 3D/4D Controversy and Non-Present Objects" (1994).
Text Colour Conventions (see disclaimer)
- Blue: Text by me; © Theo Todman, 2020
- Mauve: Text by correspondent(s) or other author(s); © the author(s)