Standard perdurantism holds that we are four-dimensional worms made up of three-dimensional temporal parts. Many of the changing properties that we think of ourselves as having directly, we actually have derivatively from the temporal parts. Thus, I am typing a post in virtue of having a temporal part typing it up, and I am conscious of the screen in front of me in virtue of a temporal part of me being conscious of it.
Standard perdurantism has many problems, for instance:
- Perdurantism commits one to proper parts, and implausibly thin and hyperplanar ones.
- Surely I am that entity which is non-derivatively consciously rather than that entity which is derivatively conscious.
- Perdurantism normally comes along not just with slices, but thicker temporal parts. But then Merricks argues that we cannot know how old we are. For all I know, I might be the temporal part from five minutes ago until now (in which case I am five minutes old), or from ten minutes ago until now (in which case I am ten minutes ld), and so on. Only a handful of temporal parts containing my present stage have the age I think myself to have, so probably I don't have the age I think myself to have.
There is, however, a perdurantism without any of these problems, if one accepts the right kind of trope theory. Suppose I exist at t. Then my existing at t is a trope of me, call it et. At least unless t is the first moment of my existence, et is an accidental trope: if I perished before t, then I wouldn't have had et. (If essentiality of origins holds, then it is an essential property of me that I exist at the first moment of my existence.) Note that I am not committing myself to the controversial thesis that existence is a property. Even if existence isn't a property, it is plausible that existence in a location—i.e., spatial locatedness at x—is a property. And if so, then why shouldn't temporal locatedness at t be a property?
I now suppose that I am a four-dimensional entity that has (where the "has" is not tensed) all of the et tropes (where t is a time during my existence): it is true to say that I exist at all these times. But many of the temporally qualifiable predicates, like "is conscious" and "is bent", that apply to me apply in virtue of et itself having certain tropes. Thus, I am now bent or conscious in virtue of enow having a certain bendedness or consciousness trope.
Strictly speaking, it's not enow that is bent or conscious, but it has the kind of trope which makes that substance that has the enow trope be bent or conscious. Compare this: If I am gorging myself, then that happens in virtue of an eating trope itself having a gorging trope. But the eating trope isn't gorging itself. It is I who am gorging myself. So the gorging trope is a trope of eating such that any substance that has the eating trope with the gorging trope gorges itself. The gorging trope, thus, makes me—the substance—be a gorger and makes my eating trope be not a gorger, but gorgingly. This is linguistically tricky.[note 1]
On standard perdurantism, I persist over time in virtue of having temporal parts that exist at various times. On this trope perdurantism, I persist over time in virtue of having temporal locatedness tropes.
On this theory, the temporal locatedness tropes et play the role of the temporal parts of standard perdurance. But they aren't parts. So we aren't committed to parts, much less implausibly thin and hyperplanar ones.
We also do not have the problems in (2) and (3). For while I am conscious at t in virtue of et having a certain consciousness trope ct, that consciousness trope doesn't make et be conscious. So while I am conscious in virtue of something other than me—namely, et—being a certain way, I am not conscious in virtue of something other than me being conscious. Thus, I do not derive my consciousness from the consciousness of anything else, and so I am non-derivatively conscious. I do derive my consciousness from something else being a certain way, but when that something else is a trope of me, that's quite innocent. Thus, (2) is not an issue here.
Nor is (3), for the obvious reason that a fusion of et-type tropes, even if there is such a fusion (which I very much doubt), doesn't think. It's substances that think, and they think in virtue of having certain tropes. The tropes don't think, and neither do their fusions.
I don't think this is the whole story. If I were seriously defending this story, I wouldn't say that I have the trope et directly. I might say that I have the trope et as a trope of my humanity, where my humanity may well be the only trope I have directly (see the paper of mine here).
I don't know if the above story is true. I am a bit sceptical of the thinness and hyperplanarity, as it were, of the et tropes—they don't seem to me to be very natural. And I am not 100% sure I want to commit to tropes. But this version of perdurantism might be true.
Note, also, a neat thing. Normally the perdurantist needs to argue why perdurance is preferable to exdurance. But I do not think there is any plausible trope exdurantism paralleling this trope perdurantism.
Objection: The trope et is a part of me, so this devolves to a more standard perdurantism.
Response: Maybe in some sense my tropes are parts of me. But they are different sorts of parts from the kinds of parts that standard perdurantism invokes. For tropes depend, at least for their identity, on that which they are tropes of. But the whole is constructed out of the temporal parts on standard perdurantism. So trope perdurantism reverses the order of grounding.