One of the points I made earlier was that presentism as a non-tautological, substantive thesis in the philosophy of time cannot be formulated without the notion of existence simpliciter. I then asked David Brightly whether he accepted the notion. Here is his reply:
Do I accept the notion of existence simpliciter? Yes and No. In so far as 'X exists simpliciter' appears to be a shorthand (a computer scientist's macro) for the disjunction of tensed claims 'X existed or X exists or X will exist' then I can guardedly accept it. This does seem to capture what is meant by 'listed in the final ontological inventory', does it not? But I worry that if we aren't very careful it can lead to logical mistakes. 'Simpliciter' here is a strange beast. It isn't an adverb qualifying 'to exist' for that would make 'to exist simpliciter' into a tenseless verb, and there are no such things. Nor, I think, does 'exists simpliciter' attribute a property to an item, so I cannot see 'existence simpliciter' as a concept. There is a whiff of 'grue' about it.
The presentist faces a problem of formulation. He tells us that only what exists at present exists. The problem is to say what the second occurrence of 'exists' in the italicized sentence expresses or denotes. What are the combinatorially possible views?
A. The second occurrence is present-tensed. This reading yields tautological presentism which is of no philosophical interest. Note that if presentism is a tautological thesis, then 'eternalism,' according to which past, present, and future items are all equally real/existent, is self-contradictory. If the only viable presentism is tautological presentism, then the dispute between presentists about what exists and eternalists about what exists is of no philosophical interest and is a pseudo-dispute. This 'possibility' cannot be dismissed out of hand. I suspect that David may be luring us in this direction. We should also be clear that presentism about what exists is not the same as presentism about existence. This is a distinction the explanation of which must wait.
B. The second occurrence expresses what I will call disjunctively omnitemporal existence: the (putative) property a temporal item has if it either existed, or exists, or will exist, where each disjunct is tensed. On this approach, the presentist thesis amounts to this:
Everything in time that either existed, or exists, or will exist, exists (present tense).
But this is manifestly false. Kepler existed but does not exist (present tense). I would also add, alluding to David's 'grue' remark, that while there are disjunctive predicates, it does not follow that there are disjunctive properties. Existence simpliciter cannot be a disjunctive property any more than being either anorexic or underinflated is a property. 'Either anorexic or underinflated' is true of some basketballs, but surely, or at least arguably, the predicate picks out no property. Likewise, 'existed or exists or will exist' picks out no property even on the assumption that existence is a first-level property.
C. There is also conjunctively omnitemporal existence: the (putative) property a temporal item has if it existed, and exists, and will exist, where each conjunct is tensed. The everlasting (as opposed to eternal) God is both disjunctively and conjunctively omnitemporal. To save bytes, I will leave it to the reader to work out why this suggestion won't help us with our problem.
D. The second occurrence of 'exists' expresses timeless existence. This obviously won't work because Only what exists at present exists cannot mean that only what exists at present exists timelessly. For anything that exists at present exists in time and is therefore precisely not timeless. So the existence simpliciter of temporal beings cannot be timeless existence. Yet it must somehow be tenseless. Indeed, it it would seem to have to be irreducibly tenseless, where a definition of tenselessness is irreducibly tenseless just in case the definiens contains no tensed expressions. But then the problem becomes nasty indeed: how can temporal items, items in time, items subject to intrinsic change, both substantial and accidental, exist tenselessly?
At this point we need to note, contrary to David's claim that there are no tenseless verbs, that there are tenseless uses of 'exists' and tenseless uses of the copulative and identitarian 'is.' That the number 7 exists, if true, is tenselessly true. That the number 7 is prime is also tenselessly true. If I tell you that 7 is a prime number, it would be a lame joke were you to reply, "You mean now?" The same goes for the proposition that 7 is 5 + 2. If you object that these truths are not tenselessly, but omnitemporally, true I will say that they are true in all worlds including those possible worlds in which there is no time, and are therefore atemporally true, and thus tenselessly true.
And similarly for the eternal as opposed to everlasting God. If God is outside of time, then all truths about him are timelessly tenseless.
The above examples assume that there are atemporal items, items outside of time. I expect David to balk. If he denies that there are atemporal items, I will have him consider the case in which I say to my class, "Hume is an empiricist." A smartass might object, "Hume cannot be an empiricist because he no longer exists." I would then explain that to say that Hume is an empiricist is to use 'is' tenselessly. Similarly if I report that for Hume all significant ideas derive from sensory impressions. 'Derive' here functions tenselessly. Same with 'are' in 'Cats are animals.' The same goes for extinct species of critter. In 'Dinosaurs are animals,' 'are' functions tenselessly. Ditto for 'Unicorns are animals.'
So now I ask David: have I convinced you that there are tenseless uses of verbs in ordinary English?
E. Could we say that the second occurrence of 'exists' in Only what exists at present exists expresses the quantifier sense of 'exists'? In the quantifier sense, x exists =df for some y, x = y. We would then be saying that
Only an item that exists at present is such that something is that item
which is equivalent to
Only an item that exists at present is identical to something
which is equivalent to
Whatever is identical to something exists at present.
Socrates, however, is identical to something, namely himself, but he does not exist at present. The trouble with the existence expressed by the existential quantifier is that it is general, not singular, existence. It is the existence that we attribute to a property or to a concept when we say that it it instantiated. 'Cats exist' says that the concept CAT has instances. It is not about any particular cats, and because it is not, it does not attribute to any particular cat existence. 'Honesty exists' in ordinary English says that some people are honest, that the virtue honesty has instances. But of course those instances, honest men and women, must themselves exist. Their existence is singular existence. The latter, however, is presupposed by the so-called 'existential' quantifier and cannot be expressed by it.
Interim Conclusion
Here is the predicament we are in. Presentism about what exists seems to make sense and seems to be a a substantive (non-tautological) thesis about a metaphysically weighty topic, that of the relation of time and existence: Only what exists at present exists. But the thesis collapses into a miserable tautology if the second occurrence of 'exists' is present-tensed. So I went on a hunt for a sense of 'exists' that is not present-tensed. But nothing I came up with fits the bill or The Bill.
David, I fear, will simply acquiesce in tautological presentism, option (A) above. But 'surely' we are in the presence of a genuine metaphysical question! Or so I will argue.
Your move, David.