Suppose I've been practicing tennis for half an hour, and at this moment I am hitting the ball. Then there are two present events: my practice, *P*, and my hit, *H*. Of these events, *H* is a part of *P*. But *H* is distinct from *P*. After all, *P* started about half an hour before *H*. Hence *H* is a proper part of *P*. If the Axiom of Weak Supplementation is true, *P* has to have some proper part *K* that doesn't overlap *H*. But *H* contains all that is *present* in *P*. So, *K* is not present. Thus, there is a non-present event, and hence presentism is false. Assuming, of course, Weak Supplementation, which is the weak point of this argument.

I myself think that Weak Supplementation and Presentism are *both* false. The argument gets half-way: at least one of the two is false. (There is also the issue that the argument supposes a realism about events.)

## 9 comments:

You're assuming that the past time intervals of P still exist. They don't, on presentism. There does not exist, at the moment of H, any non-H part of P. Indeed, the only sense in which P exists is that the H itself is not some unconnected, random H, but rather a "P-induced H" or an "H for the sake of continuing P". The H itself is the particular H that it is because it is perpetuating P. But P is not some extended event that exists at any time other than now, on presentism (obviously).

I am not assuming that past time intervals of P still exist. All I assume is that P has been going on for half an hour, while H has not been going on for half an hour.

If the presentist cannot say things like: "This war has been going on for three years now", presentism is hopeless.

If the past intervals don't exist, then P only has one part: the part that is concurrent with H. Yes, the presentist can say "this has been going on for years", because that is true. But the only part of it that exists (at all) is the current part. So there is no issue about the current part being a subset of some larger set of parts. The larger set does not exist.

Does this mean that the tennis practice doesn't exist?

The practice does exist insomuch as the current hit that I'm performing is a continuation of the practice I'm engaged in.

So it seems there are two practices: one is a current hit and the other is a practice. And Weak Supplementation is violated.

Two practices? Why? And I also don't understand why Weak Supplementation is violated. Weak Supplementation has to do with parts of wholes. In such situations a "whole" exists, and there are proper parts of it. In this case, the only sense in which the "whole" exists at all is as a fact about the current hit (among many other facts). There is no larger area in existence of which H is a proper part, so Weak Supplementation doesn't enter into it. Now, on a historical analysis of the overall practice (treating it as a completed whole) the hit is just a proper part, but then WS is true, since there are indeed other parts of P of which H is not a part.

Hitting is a practice and practicing is a practice. (I may have confused you by using "practice" in a different sense.)

Clearly, H is a part of P.

If H is a part of P, then either H=P or H is a proper part of P.

Since not(H=P), H is a proper part of P.

But, Pruss, if the only part of P that exists is the part which is manifest in H, then there does seem to be a sense in which H = P. The H in question is not some isolated hit, it is the particular hit that is defined by P and which perpetuates P at the current moment. So, at this moment, P exists only insomuch as H is partially defined by being "P-perpetuating" and H exists only as H because it is perpetuating P (otherwise it would be an isolated, random hit). They are intertwined, and there are no parts of either of them which exist at this moment aside from that.

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