Van Inwagen on Lewis' Agument for Temporal Parts

VI says on p. 126 "What are temporal parts supposed to be? - or, if you like, What is 'temporal part' supposed to mean?" 

We continue on in this vein with a candidate explanation which is rejected. Then we get on p. 129 "What other explanations [of 'temporal part'] are available?" Then we get the long passage from the appendix to survival and identity including the part where L explains what he means by person stage. The passage includes the argument. And forestalling misunderstandings. 

In response VI says (p. 130) "We could easily devise some sort of set-theoretical object to play the role of the 'career' of a person: perhaps a function from moments of time to sets of momentary properties could be called a career, and a given career could be said to be the career of a given object if its domain is just the set of moments at which the object exists and it assigns to any moment just the set of momentary properties that object has at that moment.  A part of the career of a person or other object would then be a function whose domain is a subset of the career's domain and which, in its domain, takes on the same values as the career.  It follows from our definition of 'career' that a part of a career is itself a career, though not necessarily the career of anything. A Lewis-part of a given person is an object whose career is part of the career of that person." 

Alas this departs fairly significantly from Lewis' definition of a person stage. Lewis' definition doesn't bring in almost any of this baggage. It's done much more from an intuitive level. Most importantly, it doesn't bring in the concept of a part, i.e., the stage thing being a part of something else. One important thing in the explanation of person stage is that it's the kind of thing that could be a part of a worm or whatnot. The two other critical things that are left out of here in the attempt to capture what Lewis says with a Lewis part are: (a) a stage in this explanation by Lewis is something that exists very briefly; and (b) it's something that has only the properties something can have very briefly. A Lewis part can last for 200 years and have whatever properties a 200 year old thing can have. 

VI doesn't think it's possible for there to be proper Lewis parts. We've lost sight here of something very important. I.e., we got here because VI didn't understand what a temporal part was supposed to be. And his attempted recapitulation of Lewis' definition just almost completely ignored what Lewis said. To some extent this is understandable. You would expect to find in the definition of a temporal part some allusion to the thing being a part of something. Yet, you don't get anything remotely like that in L's account of a person slice. 

VI says (131) "I can't see how there could be any such things" as proper temporal parts. "I cannot see how two person-stages could exist 'in succession, one right after the other but without overlap.'"

Note that you could instead pick the first hour "slice" of Descartes and the last hour slice of Descartes - as far as getting the slices to compose something together their being immediately successive or not will not be dispositive. "God could, I suppose, create ex nihilo, and annihilate a year later, a human being whose intrinsic properties at any instant during the year of its existence were identical with the intrinsic properties of, say, Descartes at the 'corresponding' instant in, say, the year 1625." (131-2)

It is perhaps noteworthy that 1625-Descartes lasts way too long to be a stage in the sense explained by Lewis in the passage quoted by VI. Other than that, VI is granting the main essence or maybe even more of the first premise of Lewis' argument. 

132: "And if God could do that, he could certainly create and annihilate a second human being whose one-year career corresponded in the same way to the 1626-part of Descartes' career." 

So, possibly, there is a 1625-Descartes. And possibly, there is a 1626-Descartes. And since this is a "second human being," the 1625-Descartes is distinct from the 1626-Descartes. 

"But could God, so to speak, lay those two creations end-to-end?" It's noteworthy that VI calls them "two creations," evidently indicating that the 1625-Descartes and the 1626-Descartes are distinct. 

"Well, he could create, and two years later annihilate, a human being whose two-year career corresponded to the 1625/1626-part of Descartes' career." 

From what VI has conceded I think you can force him into a corner or two to allow his view that God can't create a scenario with both 1625- and 1626-Descartes, and they are next to each other, and they are distinct. We don't get as far as the composite notion since God can't make them next to each other and distinct. 

For VI: Possibly there is an object that has the 1625-1626 career of Descartes. Call it 1625-1626 Descartes. That object does not have proper temporal parts. 

Possibly, there is a 1625 Descartes. Call it 1625 Descartes. 

Possibly, there is a 1626 Descartes. Call it 1626 Descartes. 

1625 and 1626 Descartes are distinct. 

Consider the 1625-1626 Descartes world. Does 1625 Descartes exist in that world? Does 1626 Descartes? My initial thought was that yes they both exist in that world. But they are identical there. Which maybe is what VI thinks. If so, then X and Y can be identical in one world but distinct elsewhere. Which is weird. 

Part of what puzzles me is the statement that 1625 Descartes and 1626 Descartes are distinct. I'm not sure how it works to compare really in any way things that don't exist in the same world. 

Consider this possible, nonactual thing X. And compare this certain maybe other possible nonactual thing Y. Maybe we want to say that they are distinct. What are we saying when we say that? I suppose we could say that X is taller than Y. That would mean that X's height in its world is larger than Y's height in its world. Identity doesn't seem like a world-bound phenomenon.  

Some options: 

(1) 1625 Descartes exists in the 1625-1626 Descartes world. 

(2) 1625 Descartes does not exist in the 1625-1626 Descartes world. 

I suppose after all I'm not sure why one would be confident that the possible 1625 Descartes is distinct from the 1626 Descartes. Maybe one can stipulate that kind of thing...? The feel one gets from VI's treatment is that these are metaphysical discoveries. One discovers that it's possible for God to create 1625 Descartes. One discovers that it's possible for God to create 1626 Descartes. And of course it's not a prominent feature of the discussion but the description of these entities as distinct sounds like something that is read off of reality as opposed to be stipulated into existence. Why couldn't it be that there is a single thing that in one world is 1625 Descartes and in another possible scenario is the 1626 Descartes? 

I dwell on this because it's obviously so very critical whether these things are identical or diverse. Let's try out the idea that 1625 Descartes doesn't exist in the 1625/1626 scenario. 

Look who's back on the program

I had totally forgotten I had this. I had this idea to do a blog, not remembering that I had done a blog before. Well actually I had remeembered I did a blog before, but I didn't remember about this blog. So that's good. I already this and don't need to set anything up.

Anyway, I wanted to talk about some time related things. One time related thing I wanted to talk about relates to how time has a sense or a direction.

"Now this fact that there is a change in the B series which goes from earlier to later is sufficient to show that, of the two generating relations of the series, the relation of the earlier term to the later is more important than the relation of the later term to the earlier. For the relation of the earlier to the later takes us in the direction from earlier to later. Starting from any point P in the series, we shall find it to be earlier than Q, and shall then find Q to be earlier than R and so go on continually from earlier terms to later terms. On the other hand, if we start from P and take the relation “later than” we shall find that P is later than 0, which is later than N, which is later than M and so go on from later to earlier terms. And thus the relation of “earlier than”; gives us a sense of the series which agrees with the direction of the change, while the relation “later than” gives us a sense opposed to the direction of the change. The first of these relations, then, expresses the nature of the series more adequately than the second, and we may call the sense from earlier to later the Fundamental Sense of the series."

Anyway, I was thinking about the concept of earlier-later having an intrinsic sense, which Nathan thinks is such a big deal to making something the time-generating relation. And yet Nathan really is unable to specify in a clear way what it is for the earlier than (or later than) relation to have an intrinsic sense. It's a bit frustrating and disappointing to be honest. I suppose I should not worry about what in the world that might mean. I don't really know what he means when he says it and I don't have an independent grasp of any concept or phenomenon that might be 

Anyway. I'm now in Michigan on vacation. In a hotel room. Because it's a rainy day and the coronavirus means everything indoor is closed plus my daughter doesn't want to brave the weather. I think that covers it.