Eternalism and future non-existence

I go back and forth on whether this is a strong argument against eternalism:

1. Given eternalism, it is guaranteed to be eternally the case that one exists simpliciter, even if one’s existence comes to an end.

2. Given eternalism, one’s existence coming to an end is just finitude in the forwards temporal direction.

3. If it is guaranteed to be eternally the case that one exists simpliciter, finitude in the forwards temporal direction would not be something to be dreaded.

4. So, given eternalism, one’s existence coming to an end would not be something to be dreaded. (1–3)

5. One’s existence coming to an end would be something to be dreaded.

6. So, eternalism is false. (4–5)

(As a theist, I think our existence does not come to an end. Hence the hypothetical “would” in (5).)

The intuition behind (3) is that finitude in the forwards temporal direction, given that one exists simpliciter, is akin to finitude in the backwards temporal direction or along a spatial axis, and these are clearly not to be dreaded.

But, on reflection, I think the eternalist can make very good sense of the appropriate attitudes to an end of existence. Consider this: If I were threatened with amputation of the part of me below the head—i.e., with being reduced to a head in a life-support tank—that would be something to be dreaded. It would be something to be dreaded, because the kind of functioning that is natural to human beings requires the below-the-head portion of the body. On the other hand, we could imagine sessile aliens that are very much like human heads, and there is nothing dreadful about the life of these aliens. These aliens’ lack of the below-the-head functioning normal humans enjoy would not be a deprivation.

Thus, human flourishing has spatial requirements: we require all of our body to fully flourish. Similarly, human flourishing has a robust temporal requirement: it requires an eternal future. This is because of the nature of human flourishing. Plausibly, human flourishing has a drive to infinity, requiring endless growth knowledge of reality and relationship with others. (This is probably not the whole story, but it will do for this post.) But our flourishing does not require spatial unlimitedness—on the contrary, there is a maximum size along each spatial axis such that a human being that is too big along that axis is not a fully flourishing human being.

We are four-dimensional beings, and we require a specific four-dimensional shape to flourish: a shape that is not too small and not too large in the three spatial directions and that is infinite in the forwards temporal direction. A finite future is a terrible truncation.

Now not every animal is like humans. Brute animals do not require an eternal future to be fully flourishing: they can achieve complete flourishing in a finite life, say because the lack the drive to the infinite that humans have. If we were like that, it would not be appropriate for us to dread future non-existence. Not being inclined to dread future non-existence is hard for us to imagine, because the drive to the infinite arises from such deep features of our nature. But philosophically, it makes perfect sense to think that there could be beings that can complete their flourishing in a finite compass.

The eternalist’s seeing a future end of existence of a human as a terrible truncation, but as not necessarily a terrible truncation in a non-human, seems very compelling. On the other hand, I think it is harder for a presentist to make sense of the difference here. Future non-existence seems really bad, because future non-existence on presentism would imply that eventually one will not exist simpliciter, and that seems dreadful. But the dreadfulness of this seems to have to do with the value of existence simpliciter, and not with our nature. Thus, we may have a story as to why it would make sense for a presentist to dread an end to existence, but that story proves too much: for that story would apply even if the presentist were the kind of non-human that doesn’t need an infinite future for flourishing.