Caesar exists no more

Over at the Maverick's, in the course of discussing an argument of Ed Ockham's, Bill makes some strange claims.  First, he says that
There is no such thing as Caesar any more
is a Moorean truth, that is, beyond the reach of reasonable controversy.  For me, and for Ed Ockham, this implies that there was such a thing as Caesar but that there isn't now.  No, says Bill, to reach this conclusion we need the metaphysical assumption of Presentism.  This can be stated as
Necessarily, only temporally present concrete objects exist.
This seems to me a logical truth related to how the adverbial phrase 'temporally present' interacts with the present tensed verb 'exist'.  But No again, Bill seems to say, 
we can reject presentism in favour of the plausible view that both past and present concreta exist, i.e., are within the range of our unrestricted quantifiers.
Under this view it appears that
...there is such a thing as Caesar, it is just that he is past.
Strictly speaking, this is a contradiction:  the second clause takes away what is granted by the first.   What are we to make of this?  I think a clue lies within Bill's phrase
are within the range of our unrestricted quantifiers.
The thought here might be that from
Caesar was a Roman (*)
we can infer, by existential generalisation,
∃x. x was a Roman, (**)
and translating this back into ordinary English we arrive at
There exists x such that x was a Roman. (***)
Echoing Ed Ockham here, I think this shows the perils of an uncritical formalisation.  The last assertion seems to have the imprimatur of formal logic behind it, yet it cannot follow from * for it claims that there is (present tense) someone who was a Roman, and the world's human population might have vanished by now.

The 'there exists' or 'there is' translation of ∃ is idiomatic of the mathematical language for which predicate calculus was developed.  But mathematical talk is untensed, taking place in an utterly static world.  If we want to apply the predicate calculus to the tensed statements of ordinary language in a changing world we need to be a little careful.  In this comment thread Ed Ockham suggests that we should translate (**) as
for some x, x was a Roman,
or indeed just
something was a Roman.
This works perfectly well for the eternal present of mathematics, and I suspect, for ordinary, tensed, language. So I throw down another challenge:  Can anyone offer an example where this interpretation leads to trouble?

Finally, a slogan:  Anti-presentism isn't a substantive metaphysical thesis.  It's a campaign to persuade us to use the word 'exists' in a different way.

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