An argument that the moment of death is at most epistemically vague

Assume vagueness is not epistemic. This seems a safe statement:

1. If it is vaguely true that the world contains severe pain, then definitely the world contains pain.

But now take the common philosophical view that the moment of death is vague, except in the case of instant annihilation and the like. The following story seems logically possible:

2. Rover the dog definitely dies in severe pain, in the sense that it is definitely true that he is in severe pain for the last hours of his life all the way until death, which comes from his owner humanely putting him out of his misery. The moment of death is, however, vague. And definitely nothing other than Rover feels any pain that day, whether vaguely or definitely.

Suppose that t₁ is a time when it is vague whether Rover is still alive or already dead. Then:

3. Definitely, if Rover is alive at t₁, he is in severe pain at t₁. (By 2)

4. Definitely, if Rover is not alive at t₁, he is not in severe pain at t₁. (Uncontroversial)

5. It is vague whether Rover is alive at t₁. (By 2)

6. Therefore, it is vague whether Rover is in severe pain at t₁. (By 3-5)

7. Therefore, it is vague whether the world contains severe pain at t₁. (By 2 and 6, as 2 says that Rover is definitely the only candidate for pain)

8. Therefore, definitely the world contains pain at t₁. (By 1 and 7)

9. Therefore, definitely Rover is in pain at t₁. (By 2 and 8, as before)

10. Therefore, definitely Rover is alive at t₁. (Contradiction to 5!)

So, we cannot accept story 2. Therefore, if principle 1 is true, it is not possible for something with a vague moment of death to definitely die in severe pain, with death definitely being the only respite.

In other words, it is impossible for vagueness in the moment of death and vagueness in the cessation of severe pain to align perfectly. In real life, of course, they probably don’t align perfectly: unconsciousness may precede death, and it may be vague whether it does so or not. But it still seems possible for them to align perfectly, and to do so in a case where the moment of death is vague—assuming, of course, that moments of death are the sort of thing that can be vague. (For a special case of this argument, assume functionalism. We can imagine a being of such a sort that the same functioning constitutes it as existent as constitutes it as conscious, and then vagueness in what counts as functioning will translate into perfectly correlated vagueness in the moment of death and the cessation of severe pain.)

The conclusion I’d like to draw from this argument is that moments of death are not the sort of thing that can be non-epistemically vague.

Note that 1 is not plausible on an epistemic account of vagueness. For the intuition behind 1 depends on the idea that vague cases are borderline cases, and a borderline case of severe pain will be a definite case of pain, just as a borderline case of extreme tallness will be a definite case of tallness. But if vagueness is epistemic, then vague cases aren't borderline cases: they are just cases we can't judge about. And there is nothing absurd about the idea that we might not be able to judge whether there is severe pain happening and not able to judge whether there is any pain happening either.