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Monday, May 04, 2020

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I think that in speaking of “vestiges,” we must be conscious of variations in quality that allow certain vestiges to retain something of the past more faithfully than others. The degree to which they succeed in doing so reduces both the lostness of the past and the degree to which its reconstruction is dependent upon present storytelling. They permit something more definite of the past to come into the present. As a historian of pre-modern Europe, I know when I come across remnants of this type in an Italian archive. The story that they tell is independent of any narrative or analysis that I might eventually form out of them. They have a solid simplicity about them. They are simply there, fragments of what is past, yes, but fragments rather complete in themselves, as, for instance, a photograph in our own modern times. Is this observation relevant to your discussion and worthy of being included in it? I am not sure, since I am not a philosopher, but I do know that this differentiation among vestiges is an assumed fact or historical research.

a) On presentism, whatever remains of the past must be locatable in the present.
Which is trivially true. If the remains exist, then they can in principle be located (perhaps not in practice).

b) Most past events leave no causal traces in the present.

Agree.

Therefore:
c) The totality of causal traces of the reality of the past in the present is incomplete.

I.e. not all past objects leave identifiable remnants. (Of course the atoms still exist, if physics is true, but set that aside).

d) The past is complete.
Not entirely clear what this means. I assume it means: any object that once existed can be the subject of a proposition, and any such proposition is true or false. E.g. assume Jesus had a cat. Then that cat either died before the age of 12, or not. No presentist will disagree with the disjunction.

Therefore:
e) The past cannot be identified with the totality of its causal traces in the present.

Agree.

Therefore:
f) Presentism cannot accommodate the fully determinate (complete) reality of the past.

I disagree with the ‘therefore’. How does (f) follow from the previous statements? I stop here.

I question whether the past is really necessitas per accidens on Ockham-like grounds. (I'm not sure Ockham himself ever questioned it, but that is besides the point.) Here is a quick omnipotence argument. (i) Suppose eternalism or growing salami theory; (ii) By the doctrine of divine conservation and God's ontological ultimacy, everything depends on God for its existence, God depends on nothing for his, and God can “withdraw his assent” from anything to make it cease to exist simpliciter; hence (iii), God can annihilate anything that exists simpliciter; hence (iv), on eternalism and growing salami theory, God can annihilate past items; hence (v), if eternalism or growing salami theory, the past isn't necessitas per accidens. (Furthermore, since the present is compatible with multiple pasts, it seems plausible that God could alter the past without altering the present.)

However, this argument fails on presentism, for on it God can't annihilate that which no longer exists. So, a potential aporia:

(1) The fixedness of the past requires presentism (see above).
(2) The fixedness of the past is inconsistent with presentism (see your arguments).

Vito,

I welcome your contribution since I am concerned not to say anything false about the actual practice of historians. Correct me if I am wrong, but historians tacitly presuppose the reality of the past, by which I mean the thesis that what happened in the past is independent of our present thinking about it. The historian qua historian doesn't thematize this presupposition. But the philosopher does and asks what it implies for the philosophy of time.

I should think that the historian qua historian tacitly presupposes that the past is a realm of fact, not fiction, that it is actual, not merely possible, and that it is in some sense that he qua historian doesn't worry about, 'there' to be investigated on the basis of the documentary evidence that he finds in an archive, say.

I said that the past is a realm of fact, not fiction. That is of course consistent with the existence of historical novels.

I said that the past is actual, not merely possible. That is of course consistent with there being unrealized possibilities in the past. For example, S. Kierkegaard and Regine Olsen actually existed, and it is a fact that they were engaged, as well as a fact that SK broke off the engagement. Around that time, there was the possibility -- one that remained unrealized but at the time was realizable -- of their getting married. That possibility belongs to the past: it is no longer realizable. It was grounded in the powers of actual past individuals.

I said that the past is in some sense 'there.' Deny that and you are saying that the past is nothing, in which case historians have no object of study. An historian poking through an archive is not, qua historian, studying pieces of paper and the geometrical and chemical properties of the marks on them, etc. He takes them as pointing to past events. He is not interested, qua historian, is the size, shape, chemical composition, flammability, etc. of a birth certificate as such, but in the person whose birth is thereby certified, and where he was born and to whom, etc.

The task of figuring out the sense in which the person is 'there' to be investigated falls to the philosopher. The historian is best advised not to worry about it lest it distract him from his historical research.

And of course, to say that a wholly past individual is 'there' to be investigated is not to say the he is temporally present! That should be blindingly evident.

Ostrich,

On presentism, if x is wholly past, then x is nothing. You don't agree. That suggests that yours is a tautological presentism: for things in time, whatever exists, exists now. (Both occurrences of 'exists' in the present tense -- 'now' redundant.) If x is wholly past, then x existed. That's all that needs to be said. No problem arises about the reality of the past.

Problemverlust!

Cyrus,

Sorry, but I am not getting your argument.

Bill,

Here is another variation on the same argument. Suppose eternalism, that contingent existence is unity, and that unity requires an External Unifier. Surely it's within God's power to "release" the internal unity of one of Hitler's nose hairs and thereby alter the past, destroy it, and thereby alter the past but not present. And if it's possible for God to do that, then the past isn't unalterable.

(Note: I needn't, like Ockham, assume that God can do everything logically possible for this argument. I can perfectly well allow that some things depend on other things as long as there are also things on which nothing depends.)

Here is the basic form of omnipotence arguments (in case it makes the above clearer):

(1) God can do everything logically possible.
(2) x is logically possible.
(3) Hence, God can do x. (1, 2)
(4) If God can do something, it's metaphysically possible.
(5) Hence, x is metaphysically possible. (3, 4)

So for the possibility of altering the past:

(1) God can do everything logically possible.
(2*) It's logically possible to alter the past.
(3*) Hence, God can alter the past. (1, 2)
(4*) If God can alter the past, it's metaphysically possible to alter the past.
(5*) Hence, it's metaphysically possible to alter the past. (3, 4)
(6) If the past is necessitas per accidens, it's not metaphysically possible to alter the past.
(7) Hence, the past isn't necessitas per accidens. (5, 6)

The only difference in my argument is that I'm not assuming as strong an omnipotence principle as 1. For instance, I would be perfectly fine modifying it to allow for necessary connections in the world. But I contend that even after you pare down the principle, it will remain possible for God to alter the past. (Of course, coming up with an exact formulation of such a principle is notoriously hard.)

With the exception of those who embrace decadent postmodern historical thinking, you are right in stating that “historians tacitly presuppose the reality of the past, by which I mean the thesis that what happened in the past is independent of our present thinking about it.” The past, the vestiges of which are uncovered in the present, remains a “realm of fact, not fiction” as you nicely put it. The explanations and interpretations of this discovered realm by historians, which alter over time, derive their relative truth values from the degree to which they approximate it. So to pick up on your example of a birth certificate, which would take the form in Europe during early modern times of an entry of birth in a parish register, the historian, finding the birth of someone named X in a particular village in a particular year has uncovered a past fact, a trace of the unchanging past. He may go on and record hundreds of such births and then proceed to do the same with marriages and deaths, all vestiges of high quality, and in doing so reconstruct the histories and life cycles of scores of families. Now, in moving from the most brute facts to his assemblage of them into a coherent interpretive framework, he will be making certain choices, guided by the theories and techniques to which he adheres, and in making these choices, he may succeed to a greater or lesser extent in giving us something of the past, the “there” which grounds and makes possible the practice of history.

(2*) It's logically possible to alter the past.

This isn't obvious to me.

To change the past, you have to pick a proposition P0, true at some past time t0 and make it so that at t0, not P0 was true. In other words, at the present time, t1, it is originally true that

(P1) At time t0, P0 was true.

Now it is true that

(~P1) At time t0, P0 was false.

This is a logical contradiction. It does no good to say that P1 has changed, because P1 is not relative to time--it picks out a specific time--so what would it mean for P1 to change? Change requires a past, so that if P1 changed from true at t1 to false at t1, then there must have been a time when P1 was true at t1. When was that time?

The idea of changing the past seems to involve a confusion of concepts where one models the past as a geometric line and then imagines making changes to the line, while not noticing that the changes have no place in the model because when you are viewing time as a line, any change must be modeled as a fixed feature on the line.

David,

To change the past, you have to pick a proposition P0, true at some past time t0 and make it so that at t0, not P0 was true. In other words, at the present time, t1, it is originally true that

(P1) At time t0, P0 was true.

Now it is true that

(~P1) At time t0, P0 was false.

This is a logical contradiction. It does no good to say that P1 has changed, because P1 is not relative to time--it picks out a specific time--so what would it mean for P1 to change?

I'm not sure what it would mean for a non-temporal, "Platonic" proposition to change, but presentists and growing salami theorists already allow that there is some (perhaps analogically similar) sense in which they do, in fact, change. It was false that Napoleon won the battle of Austerlitz before the battle of Austerlitz. After the battle of Austerlitz, it in some sense "became" true that Napoleon won the battle of Austerlitz. Similarly, the proposition that the battle of Austerlitz is occurring was true during the battle of Austerlitz, but in some sense changed and "became" false after Austerlitz. This doesn't so much have to do with whether or not P1 exists in time as whether or not something necessitates P1's truth.

(I'm assuming that P1 is true if and only if there exists simpliciter some entity, T, which necessitates P1's truth. If no such entity exists, P1 isn't true; if every such entity "ceases" to exist, P1 "ceases" to be true. T may be temporal; P1 and the necessitation or "in virtue of" relation, however, aren't.)

Cyrus,


I'm not sure what it would mean for a non-temporal, "Platonic" proposition to change

That is not an assumption of my argument. You may replace "proposition" with "sentence" and the argument still goes through.

presentists and growing salami theorists already allow that there is some (perhaps analogically similar) sense in which they do, in fact, change. It was false that Napoleon won the battle of Austerlitz before the battle of Austerlitz. After the battle of Austerlitz, it in some sense "became" true that Napoleon won the battle of Austerlitz

I'm not sure this situation is analogous to what you were proposing before--that a historical fact that was once true becomes false--but in any case, this situation is not vulnerable to either of my arguments. First, there is no time t at which "Napoleon won the battle of Austerlitz" is both true and false, so there is no logical contradiction. Second, ignoring the time at which it is said, "Napoleon won the battle of Austerlitz" can be first false and then true, but the question "when did it change" has an answer--it changed at the conclusion of the battle.

This doesn't so much have to do with whether or not P1 exists in time as whether or not something necessitates P1's truth.

I'm not sure I understand this this comment, but if you are referring to my comment that P1 is not relative to time, what I meant by that is that P1 is not the sort of proposition that is interpreted according to a changing time like "I'm hungry" is. The truth of "I'm hungry" depends on when it is said. By contrast, the truth of "I was hungry at noon on May 4, 2020" is not relative to when it is said (modulo that the verb tense would have to change if May 4, 2020 were not in the past).

Since I'm a bit uncomfortable using the somewhat hazy analogical notion of “change”, here is a follow-up thought: Perhaps truth isn't an irreducible, intrinsic, non-relational property that propositions gain or lose, but something reducible to the mereological sum of a proposition and its truthmaker. Then you don't need propositions to change for their truth or falsity to, only truthmakers. This, if it holds up, removes the need to resort to “change”. (Is this move ad hoc? Here is a plausible seeming principle to make it less so if it is: if it's impossible that an entity, P, should exist and an entity, Q, not exist and impossible that Q should exist and P not exist, P and Q are identical.)

But feel free to ignore this when reading the previous comment. It's just something that occurred to me and seemed worth sharing.

On second thought, never mind the principle in the follow up comment. It collapses all propositions into one, even though those propositions (e.g. 2+2=4 and 2+2=5) are clearly distinct. That's what I get for borrowing half a naturalist's principle!

David,

Then I don't understand your argument. Sorry.

To change the past, you have to pick a proposition P0, true at some past time t0 and make it so that at t0, not P0 was true. In other words, at the present time, t1, it is originally true that

The truth of propositions depends on the reality of the past and what exists, not the other way around. The truthmaking relation is asymmetric.

Bill "On presentism, if x is wholly past, then x is nothing. You don't agree. That suggests that yours is a tautological presentism: for things in time, whatever exists, exists now. (Both occurrences of 'exists' in the present tense -- 'now' redundant.) If x is wholly past, then x existed. That's all that needs to be said. No problem arises about the reality of the past."

As I said in a separate email, I am looking for you to articulate the 'anti presentist' position in a way that makes any sense.

Perhaps I am lacking problems, but if you say there is a problem, you need to say what it is. You tried to do so above using the notion of 'completeness'. But you didn't state clearly what completeness is. The presentist agrees, of course, that the universe was created more than 5 minutes ago, that dinosaurs existed, and that their fossilised bones still exist etc. The presentist also agrees that to any individual that existed in the past, there correspond true or false (past tense) propositions, so the past is complete in that sense.

You have yet to formulate a clear thesis about what you call anti-presentism. It's not enough to accuse ostriches of lacking problems when you haven't even said what the problem is.

I mean, you're right that I'm thinking of it as God's excising part of a line. (That is why I kept supposing eternalism or growing salami theory.) You're also right that change is defined as occurring over time. But that just means that "change" was a poor choice of word on my part. You understand what I'm saying (as shown by your reference to the line analogy).

Bill "I said that the past is in some sense 'there.' Deny that and you are saying that the past is nothing, in which case historians have no object of study. "

I asked about this argument a while back. Why would a presentist want to deny that we can study, e.g. the dissolution of the monasteries in the 16th century? Then we are studying something, namely the dissolution of the monasteries. So in that sense the past is not nothing. Why would anyone deny that?

But again, what is the substantive philosophical thesis you want to wring out of this?

Morning Bill,

I sometimes think our disagreement is about how certain terms are to be used. Compare these claims,

1. The past is in some sense 'there.' Deny that and you are saying that the past is nothing, in which case historians have no object of study.

2. The past was in some sense 'there.' Deny that and you are saying that the past was nothing, in which case historians have no object of study.

I think of 'the past' in this context as collectively referring to multiple things and events. 'The wholly past' denotes a subset of the past. There is also in these sentences an implicit universal quantification over these sets. So I test the truth of these assertions by choosing randomly an element, usually Julius Caesar, making a textual substitution, and asking how comfortable I am with the modified assertions.
1'. JC is in some sense 'there.' Deny that and you are saying that JC is nothing, in which case historians (of JC) have no object of study.

2'. JC was in some sense 'there.' Deny that and you are saying that JC was nothing, in which case historians (of JC) have no object of study.

I find I'm perfectly happy with (2'). Not so with (1'). 'JC' names a thing in time so tenseless 'is' is inapplicable. I have only present tensed 'is'. My presentism says that JC in no sense is 'there'. It follows that JC is nothing, but in my view it doesn't follow from that that historians of JC have no object of study. The problem I have is that I find (2) so innocuously the right thing to say that I'm constantly surprised that you always opt for formulation (1). Is that Problemverlust?

You understand what I'm saying (as shown by your reference to the line analogy).
No, I've just read enough science fiction stories to be able to imagine what you are talking about. I can also imagine a round square so long as I am careful not to try to imagine the roundness and the squareness at the same time. I suspect that the notion of changing the past is quite similar to a round square in that it involves a similar suspension of coherent thought.

David B,

Good comment; clear and clarifying. When I speak of the wholly (purely, merely) past, I mean past temporal items that do not overlap the present. A storm that is only half over is then not wholly past, although phases of it are wholly past. A storm is a process. I don't consider myself a process, although this is a debatable point. But I clearly have a past. But I am not wholly past, leastways, not yet. I think we agree on this use of terms.

The difference between (1) and (2) goes to the heart of the matter. You plump for (2) and (2'). JC WAS in some sense 'there.' That suffices for him to be an object of historical study. You can even drop the 'some sense' business and flatly state that JC did exist and that this suffices, etc.

My objection/question is that if JC DID exist, but is now nothing, how can HE now be an object of study? When we investigate JC, the objects of investigation are not causal traces in the present. These traces are pointers to the object of study. We can learn about a burglar from his footprints, but the latter are not what interest us except as a means to identifying the burglar.

>> 'JC' names a thing in time so tenseless 'is' is inapplicable. <<

This is a telescoped or enthymematic argument. I accept the premise, but I think the conclusion is false. Why can't something in time tenselessly exist? 'Tenselessly exist' does not mean 'timelessly exist.' If there are items outside of time, then they tenselessly exist. But it is arguable that an item can be temporal and yet exist tenselessly.

This is one of the crucial issues that needs to be taken up in later posts.

David,

No, I've just read enough science fiction stories to be able to imagine what you are talking about. I can also imagine a round square so long as I am careful not to try to imagine the roundness and the squareness at the same time. I suspect that the notion of changing the past is quite similar to a round square in that it involves a similar suspension of coherent thought.

It's not at all clear to me that it's an incoherent thought, like a round square would be. That is why I bothered to bring whether or not it's a coherent thought into question. (In other words, it seems to me that even if it is incoherent in this sense more needs to be done to show it.)

In other words, it seems to me that even if it is incoherent in this sense more needs to be done to show it.
On that we can agree. I gave an a priori argument for how changing the past leads to a logical contradiction, but there is clearly something suspect about this argument because the possibility of changing the past seems to be an empirical question, which one would not expect to be resolvable by an a priori argument.

On the other hand, maybe the question is not really empirical. There are reasons to suspect that all events which would be observed as changing the past would really be something else. Alternatively, maybe it is an empirical question that is resolvable by an a priori argument much as Euclid's parallel postulate (which I claim is a priori true, though I know I am in a small company in believing that today).

Suppose I change the argument:

(1) God can do everything logically possible.
(2) It's logically possible for the past to cease to exist.
(3) Hence, God can cause the past to cease to exist. (1, 2)
(4) If God can cause the past to cease to exist, it's metaphysically possible for the past to cease to exist.
(5) Hence, it's metaphysically possible for the past to cease to exist. (3, 4)
(6) If the past is necessitas per accidens, it's not metaphysically possible for the past to cease to exist.
(7) Hence, the past isn't necessitas per accidens. (5, 6)

Now (2) is assumption of presentism.

Cyrus,

Please explain how (2) is an assumption of presentism.

Bill,

I had actually sent through another comment withdrawing the argument. But my thought was that since according to presentists that which becomes past goes out of existence*, presentists assume that it's logically possible for items (all items) that become past to cease to exist.

(I also realized, right after I posted the revised argument, that I'm unclear on what "necessitas" in necessitas per accidens means. Does it mean "In every possible world, if x has existed x exists simpliciter"? Or does it mean something along more medieval temporal lines like "If x exists simpliciter at t1, there is no time, ty, at which x doesn't exist simpliciter at t1"? Both contradict presentism. So I decided I had better back off the argument until I got a clearer idea of what I was saying.)

*It's not that which is present that goes out of existence. The present exists. So as things become past they cease to exist/undergo existential change.

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