Can presentism navigate between the Scylla of tautology and the Charybdis of absurdity? Let's see. We begin with a datum, a given, a Moorean deliverance that I think most would be loath to deny:
DATUM: if it is true that a was F, or that a F'ed, then it was true that a is F, or that a Fs.
For example, if it is true that John F. Kennedy was in Dallas on 22 November 1963, then it was true on that date that he is in Dallas on that date. For a second example, if it is true that Socrates drank hemlock, then it was true that Socrates drinks hemlock.
It follows that the present present cannot be the only present: there had to have been past presents, past times that were once present. For example there was the present when JFK was assassinated. That is a past present. Only what was once present could now be past. Suppose you deny this. Then are you saying that there are past items that were never present. But that cannot be right. For the past is the present that has passed away. It cannot be the case that the event of Kennedy's assassination was always past and never present. There was a time when it was present and a time before that when it was future. When Kennedy was inaugurated, his assassination was future; when Johnson was sworn in, his asassination was past.
Bear in mind that presentism is an A-theory. This implies that among times there is a privileged time that is absolutely or non-relationally present. So while every time is present at itself, only one time is present absolutely. This time instantiates the monadic (non-relational) property of absolute temporal presentness. This absolute property is temporary, not permanent.
So what is the presentist maintaining? He cannot be maintaining that
P-Taut: Only present items presently exist
for this is not a substantive metaphysical claim contradicted by the eternalist's substantive denial, but a mere tautology. Nor can he be telling us that
P-Solip: Only presently present items exist simpliciter.
For this is solipsism of the present moment, a bizarre if not lunatic thesis. It amounts to the claim that all that ever existed, all that exists, and all that will ever exist exists now, where 'now' is a rigid designator of the present moment, the moment at which I am writing and you are reading. If our presentist pals are not solipsists of the present moment, then they cannot be saying that only what exists at the present present exists simpliciter, and so they they must be telling us that only what exists at a given present (whether past, present, or future) exists. Thus
P-Always: At every time t, only what is present at t, exists simpliciter.
This seems to do the trick. What is says is that, at every time t, only what is temporally present at t belongs in the ontological inventory, the catalog of what there is.
Thinking a little deeper, however, (P-Always) seems contradictory: it implies that at each time there are no non-present times and that at each time there are non-present times. For if one quantifies over all times, then one quantifies over present and non-present times in which case there are all these times including non-present times. But the bit following the quantifier in (P-Always) takes this back by stating that only what is present at a given time exists simpliciter.
It is obvious that (P-Taut) and (P-Solip) are nonstarters. So we are driven to (P-Always). But it is contradictory. The presentist wants to limit the ontological inventory, the catalog of what exists, to temporally present items. To avoid both tautology and the solipsism of the present moment, however, he is forced to admit that what exists cannot be limited to the present. For he is forced to quantify over times that are not present in order to achieve a formulation that avoids both (P-Taut) and (P-Solip).
The presentist needs the 'always' to avoid Scylla and Charybdis, but it doesn't keep him from drowning. He is forced to jump out of his privileged temporal perspective from within time and view matters sub specie aeternitatis. He is forced into an illict combination of a privileged perspective within time with a view from No When, a view from outside of time. The perspectives cannot be integrated, and therein lies the root of the problem.
My interim conclusion is that presentism makes no clear sense. This does not support eternalism, however, for it has its own problems.
