(P) Possibly, I am a concrete object that is not a person.
I then gave some reasons to think that (P) is not true. The two premises in that argument were:
(5) If I am essentially a person, then it is not possible for me to be a concrete object that is not a person.
(6) I am essentially a person.
The main problem with denying (5) is that this claim seems true by definition. We generally think that one of the necessary conditions of having an essential property is that you have it whenever you’re around. But definitions can be wrong, and maybe we were wrong in thinking that having a property whenever you’re around is necessary for that property being essential to you. So it's not impossible to deny (5). But it certainly seems difficult.
There are two big problems with denying (6):
(i) It's weird to think that personhood is just an accidental property that we have. It really seems to be the case that being a person is central to our identity, or our nature. It is the kind of thing we are. But that is what essential properties are.
(ii) It's plausible to think that, were I to stop being a person, I would stop existing. But if personhood is not an essential property, it is hard to explain how this could be.
Here is what I'm going to try to do: I'm going to try to provide a picture of essentiality that allows the deniers of (5) to make their view less crazy, and the deniers of (6) to have better answers to (i) and (ii). In doing so, I will appeal indirectly to medieval discussions of eternality. The reason I am appealing indirectly is because I am having a really hard time finding source material on this (I think Duns Scotus talked about it, but I’m not sure. If anyone could point me to the right place, it would be much appreciated).
Roughly, medieval philosophers had a problem with things that exist eternally, which was as follows:
(A) God exists eternally.
(B) Our souls exist eternally.
On the assumption that God and our souls both exist, both (A) and (B) appear to be true. But there is an important difference between God and our souls: our souls came into existence, while God did not. An attempt to explain the difference between the eternality that God has and the eternality that souls have was to distinguish between two types of eternality: left-hand eternality, and right-hand eternality. A particular being is left-hand eternal if it has always existed. A particular being is right-hand eternal if it will always exist. So (A) is true on both disambiguations of eternality, while (B) is only true on the right-hand disambiguation. Our souls, unlike God, are not left-hand eternal. It is important to note that there are several ways to relate the instantiation conditions of being eternal to the conditions of being left-hand eternal and being right-hand eternal. Maybe being eternal requires either being left-hand eternal or being right-hand eternal, in which case both (A) and (B) are true. Maybe being eternal requires both being left-hand eternal and being right-hand eternal, in which case only (A) is true. Either way, it seems like the notions of left- and right-handed eternality are still useful to explain differences between God and our souls.
I propose to import this distinction into discussions of essentiality. The thought is as follows:
Definition of left-hand essentiality: property F is a left-hand essential property of object o iff
(I) o has F.
(II) Were o to acquire F, o would not have previously been concrete.
Definition of right-hand essentiality: F is a right-hand essential property of o iff
(I) o has F.
(II) were o to lose F, o would not subsequently remain concrete.
Just like with the discussion of eternality, maybe being an essential property requires having both left- and right-hand essentiality. Maybe being an essential property requires just one.
If both are required, then (5) is true: if I am essentially a person, then it is impossible for me to be a concrete object that is not a person. But it might not be so bad to reject the essentiality of personhood here. After all, we can still agree that personhood is right-hand essential, and that can explain many of the phenomena that we wanted essentiality to explain. Here's how:
To respond to (i): while acquiring personhood is may be an accident, maintaining personhood is not. So it is not too terrible to think that it is because of the kind of thing we are (persons), that we must remain persons. That's not the case for other accidental properties, like being a teenager. It is not in the nature of being a teenager that we must remain teenagers. So there is still a principled distinction between being a person and our standard accidental properties.
To respond to (ii): were you to stop being a person, you would stop existing. But this is not because personhood is essential, it is because personhood is right-hand essential
On the other hand, we could claim that essentiality only requires one of left- or right-hand essentiality. In this case, premise (6) is true: I am essentially a person. But we now how the resources to deny premise (5), since we can say that it is perfectly possible for me to be essentially a person even if I am sometimes not a person.
Maybe you have really strong intuitions about essentiality here, so that one move seems more plausible than the other (or maybe both seem equally implausible). I’m inclined to say that essentiality only requires one of left- or right-hand essentiality, and thereby reject (5). If this is right, then my argument constitutes an interesting discovery about the property of being a person: its essentiality is only right-handed.
Some issues/thoughts that I have:
#1: it seems that under my definition, being an author is a right-hand essential property. Once you write a book, you're an author forever. Here, I'm inclined to appeal to Cowling (forthcoming) in saying that only certain properties can be essences, and being an author is just not one of them.
#2: I'm wondering how much this account of essentiality can help people who think that everything necessarily exists. It seems to me that these handed essentiality is not much help to them, but I'm interested in looking at this further.
#3: Suppose you think that it is not possible for me not to have been a person. I think I can run this argument again with fetuses. A fetus is essentially a fetus, but it used to be a non-fetus (an embryo). Unless we think that there are a whole bunch of things going into and out of existence inside a uterus, we should think that some properties are right-hand essential. Thoughts?