Presentism and the intrinsicness of past tensed properties

Many presentists think that objects have past-tensed properties. Thus an object that is now straight but was bent has the property of having been bent. (Some such presentists use these properties to ground facts about the past.)

But assuming for simplicity that being bent is an intrinsic property, we can argue that having been bent is an intrinsic property as well. Here’s why. If being bent doesn’t describe an object in relation to the existence, non-existence or features of any other object (assuming being bent is intrinsic), neither does having been bent. Nor is having been bent “temporally impure”—it does not describe the object in terms of anything happening at other times, since nothing can happen at other times on presentism. It does not describe the object in relation its past or future temporal slices or past or future events involving the object, since on presentism there are no past or future objects, and there are no past or future events.

But if having been bent is an intrinsic property of an object, it seems that, by a plausible patchwork principle or by intuitions about the omnipotence of God, an object could come into existence just for one instant and yet have been bent at that instant. Which is absurd.

Losing track of time

Suppose that the full saturated truthbearers are tensed propositions (which I think is essentially what the A-theory of time comes to). Now consider an atom with a half-life of a week. I observe the atom exactly at noon on Monday, and it hasn’t decayed yet. I thereby acquire the belief that the atom has not decayed yet. Now suppose that for the next week I stop changing in any relevant respect, and maintain belief in the same truthbearers, and the atom doesn’t decay. In particular I continue to have the tensed belief that the atom hasn’t decayed yet.

But an odd thing happens. While my belief is reliable enough for knowledge initially—it has a probability 0.9999 of remaining true for the first minute after observation—eventually the reliability goes down. After a day, the probability of truth is down to 0.91, after two days it’s 0.82, and after a week, of course, it’s 0.5. So gradually I lose reliability, and (assuming I had it) knowledge, even though nothing relevant has changed in the world in me or around me.

Well, that’s not quite true. For something seems to have changed: my observation has “gotten older”. But it’s still kind of odd—the time slice of the world is relevantly the same right after the observation as a week after.

The A-theory and a countably infinite fair lottery

Let’s suppose that the universe has a beginning and the tensed theory of propositions (which is accepted by most A-theorists) is true. Then consider for each n the proposition d_n that n days have elapsed from the beginning of the universe. This proposition is contingent on a tensed theory of propositions. Exactly one of the propositions d_n is true. No one of the propositions d_n is more likely to be true than any other. So, it seems, we have a countably infinite fair lottery. But such are, arguably, impossible. See Chapter 4 of my infinity book. (E.g., it’s fun to note that on the tensed theory of time we should be incredibly surprised that it’s only 13 billion years since the beginning of the universe.)

Since the universe does have a beginning (and even if it does not, we can still run the argument relative to some other event than the beginning of the universe), it seems we should reject the tensed theory of propositions.

A tale of three horses

Consider three horses: Alexander's Bucephalus, Gandalf's Shadowfax and Dawn. Here, I am using "Dawn" as the name of a horse that has come into existence just now, so that it is now the first moment of existence for Dawn. (Imagine the claims about Dawn all being made at the first moment of its existence.)

Intuitively, there is something Bucephalus and Dawn have in common with each other that they don't have in common with Shadowfax, namely reality.

The eternalist can take this at face value and say: Bucephalus and Dawn both exist, while Shadowfax does not.

But it is difficult for the presentist to say what Bucephalus and Dawn have in common which they don't share with Shadowfax. According to presentism, neither Bucephalus nor Shadowfax exist. Of course Bucephalus did exist, but on the other hand it is false that Dawn did exist: it is Dawn's first moment. So on presentism, Bucephalus and Dawn have neither existence nor past existence in common. And they don't have future existence in common either, since Bucephalus presumably has no future (unless there is a resurrection for brute animals, which we can suppose for the sake of argument there won't be). Nor do they have timeless existence in common, since none of the three is a timeless entity.

Of course, it is true that both Bucephalus and Dawn did-or-do-exist. But that's a disjunctive property, and a similarity in respect of a merely disjunctive property is not a real similarity. Perhaps the presentist can argue that it is a disjunctive property, but not a merely disjunctive one. But barring some sort of account of the similarity this seems ad hoc. We might as well say that Shadowfax and Bucephalus have this in common, that each fictionally-or-actually-exists.

Tensed propositions and conversation

According to the doctrine of Tensed Propositions (TP), which is accepted almost all presentists, when I say "It is night" at noon and when I say it at midnight, I express the same proposition, which is true at midnight and false at noon. The opponents of TP are apt to say that "It is night" is indexical, and as said at noon and at midnight expresses different propositions. TP is compatible with there being untensed propositions, like <It is night at t₇>, but typical tensed sentences in English express tensed propositions.

Here is an argument against tensed propositions:

1. (Premise) To be in agreement with what someone has said is to accept the proposition that she expressed.
2. (Premise) If p is a tensed proposition, then x's accepting p at t₁ and y's accepting p at t₂, where t₁ and t₂ are different, does not constitute agreement between x and y.
3. There are no tensed propositions.

Argument for (1): To agree is to accept what was said. But what was said was the proposition that was expressed.

Argument for (2): Suppose I say: "It is now exactly 7 p.m." and twenty seconds later you sincerely say: "It is now exactly 7 p.m." If there are tensed propositions, then both of our utterances express the same tensed proposition. But surely your assertion expresses a disagreement with me. The point generalizes to all tensed propositions. Granted, sometimes, especially if t₁ and t₂ are within a relevant time period (say, on the same day, and p is about "today") x will be right in believing p if and only if y is right in believing p, but nonetheless x and y's agreement does not consist in mutual acceptance of p.

Even if one does not think that (1) is always true, it is very plausible that typically in communicating we are trying to communicate a proposition. But also typically, our sentences are tensed. So if TP is true, then typically we are communicating tensed propositions. But it seems essential to communicating a proposition that agreement should be constituted by mutual acceptance of that proposition. But in the case of tensed propositions that isn't what agreement is constituted by (maybe it's constituted by accepting the second-order claim that the proposition was true when it was expressed). So it can't be that our typical communication involves tensed propositions. Hence, TP is false.

Josh Rasmussen said that arguments along these lines came up independently in conversation with Peter van Inwagen.

Tense and action

Consider a version of John Perry's argument that action needs tense. You promised to call a friend precisely between 12:10 and 12:15 and no later. When it is between 12:10 and 12:15, and you know what time it is, this knowledge, together with the promise, gives you reason to call your friend. But if this knowledge is tenseless, then you could have it at 12:30, say. Thus, absurdly, at 12:30 you could have knowledge that gives you just as good a reason to call your friend.[note 1]

Here, however, is a tenseless proposal. Suppose it is 12:12, and I am deliberating whether to call my friend. I think the following thought-token, with all the verbs in a timeless tense:

1. A phone call flowing from this deliberative process would occur between 12:10 and 12:15, and hence fulfill the promise, so I have reason that this deliberative process should conclude in a phone call to the friend.

And so I call. Let's see how the Perry-inspired argument fares in this case. I knew the propositions in (1) at 12:12, and I could likewise know these propositions at 12:30, though if I were to express that knowledge then, I would have to replace both occurrences of the phrase "this deliberative process" in (1) by the phrase "that deliberative process." However, this fact is in no way damaging.

For suppose that at 12:30, I am again deliberating whether to call my friend. I have, on this tenseless proposal, the very same beliefs that at 12:12 were expressed by (1). It would seem that where I have the same beliefs and the same knowledge, I have the same reasons. If this principle is not true, the Perry argument fails, since then one can simply affirm that one has the same beliefs and knowledge at 12:30 as one did at 12:12, but at 12:30 these beliefs and knowledge are not a reason for acting, while they are a reason for acting at 12:12. But I can affirm the principle, and I am still not harmed by the argument. For what is it that I conclude at 12:30 that I have (tenseless) reason to do? There is reason that the deliberative process should conclude in a call to the friend. But the relevant referent of "the deliberative process" is not the deliberative process that occurs at 12:30, call it D_12:30, but the deliberative process that occurs at 12:12, call it D_12:12. For (1) is not about the 12:30 deliberative process, but about the 12:12 one.

The principle that the same beliefs and knowledge gives rise to the very same reasons may be true—but the reason given rise to is a reason for the 12:12 deliberative process to conclude in a phone call. But that is not what I am deliberating about at 12:30. At 12:30, I am deliberating whether this new deliberative process, D_12:30, should result in a phone call to the friend. That I can easily conclude that D_12:12 should result in a phone call to the friend is simply irrelevant.

There is an awkwardness about the solution as I have formulated it. It makes deliberative processes inextricably self-referential. What I am deliberating about is whether this very deliberation should result in this or that action. But I think this is indeed a plausible way to understand a deliberation. When a nation votes for president, the nation votes not just for who should be president, but for who should result as president from this very election. (These two are actually subtly different questions. There could be cases where it is better that X be president, but it is better that Y result as president from this very election. Maybe X promised not to run in this election.)

[I made some minor revisions to this post, the most important of which was to emphasize that (1) is a token.]

Change of facts and an argument against presentism

Patricia is a person with a strange defect. She has tensed beliefs that she fails to update. For instance, she believes that the Battle of Waterloo was two hundred years ago, and she does not change in respect of this belief—she believed twenty years ago that the Battle of Waterloo was then two hundred years ago, and in twenty years she will believe that the Battle of Waterloo will then be two hundred years ago. Presentists tend to think that the objects of beliefs are tensed propositions, and if so, then it is very plausible that her mind is intrinsically in the very same state with respect to the Battle of Waterloo in 1988, in 2028 and in 2015.[note 1] Interestingly, her belief about the Battle of Waterloo was false in 1988, is false now, will be false in 2028, but on June 18, 2015, her belief will be true.

If Patricia's believings about the Battle of Waterloo do not change intrinsically while they change from false to true to false again, it follows that this change from false to true to false is a Cambridge change. But Cambridge changes are relational. Now in the case of a Cambridge change in x, there is a y distinct from x which changes intrinsically and the change in x is a change relative to y, and x has the changing extrinsic property in virtue of y's having the changing intrinsic property. Thus, what makes Patricia's believings change in a Cambridge way from false to true to false is that something else changes intrinsically.

So what is it that changes intrinsically in virtue of the change in which Patricia's believing changes from false to true to false? Well, the only plausible candidate for an answer to this is that the object of the belief changes intrinsically. When someone falsely believes it is raining and continues to believe it until it becomes true, the belief changes in truth value in virtue of the weather changing from, say, sunshine to rain. But then Patricia's beliefs must be about something in reality. In particular, presentisms like those of Merricks on which there are no truth grounds for facts about the past are going to be falsified by these considerations.

What about presentisms like those of Bigelow and Crisp on which there are past-tensed presently existing states of affairs? Do those do better? I think not. For when a belief changes in truth value without intrinsically changing, I think it must change in virtue of a change in that which the belief is about. But the belief that the Battle of Waterloo was 200 years ago is plainly not about any present state of affairs.

One way out for the presentist is to say that believings change in correctness in virtue of a change in the truth value of the proposition that forms their content. This is intuitively wrong—believings should change in virtue of a change in that which they are about and except in higher order cases they are not about a proposition—but let us pass on that objection. But now the problem reappears in respect of the change in the truth value of the proposition (see also this past post). It does not appear that there is any intrinsic change in the proposition when it changes in truth value. For suppose that the proposition that it is raining changes in truth value with the weather. Surely, then, it changes because of the weather. But how can changes in the weather, changes in the physical world, explain intrinsic changes in the Platonic realm of propositions? (And we need to be realists about propositions for the present suggestion to have any force.) That seems very much implausible. So the proposition changes in truth value in an extrinsic, indeed Cambridge, way. But now the same problem we had with believings reappears at the level of propositions.

"Now" and other indexicals (Language, Part IV)

In English, the pitch and rate at which one speaks typically do not affect the types of the tokens that one is using. Whether you say "home" quickly or slowly, with a low or a high pitch, your utterance is a token of one and the same type. But this need not be a universal truth. One can easily imagine a language where an utterance of "home" means one thing when spoken quickly and another when spoken slowly. In that case, there are two word types here, and which type one's token falls under will be partly determined by the sequence of phonemes and partly by the rate at which one speaks. (We might represent the two word types in writing as "home" and "h-o-m-e" if we wish.)

A language provides a mechanism for classifying linguistic tokens under linguistic types. There are very few restrictions on how the classification scheme can work, except contingent ones derived from our recognitional abilities. Imperceptible differences between tokens will not do the job.

It is quite possible, then, to have a language where the classification system is time-dependent. Thus, "home" at odd-numbered hours of the day means a tank, and at even-numbered hours it means an F-16. There are, thus, two word-types with the same phonemes, and to distinguish between them you have to check what time it is. Such a language might well be useful for confusing an evesdropping enemy.[note 1]

Imagine now a language L1 where the sound "chow" when uttered at a time t denotes the time equal to t+7minutes, when t is during an even-numbered hour, and denotes the time equal to t-7minutes, when t is during an odd-numbered hour, and where the type of the word is identified by both the sound "chow" and the time of utterance. This language can be understood as containing continuum many word-types, identified partly by the time at which the word-type is tokened and partly by the phonemes. This is a very odd language, but a possible one.

Observe that in L1 no utterance of "chow" is the utterance of an indexical. What an indexical refers to depends on both the token's type and on the context of utterance. But what "chow" refers to does not depend on the context of utterance, but only on the token's type. The token's type depends on the time of utterance, but that is a different matter.

Consider now a language L2 where the sound "fow" when uttered at a time t denotes the time t, and where the type of the word is identified by both the sound "fow" and the time of utterance. Just as no utterance of "chow" in L1 was an indexical, so no utterance of "fow" in L2 is an indexical. Rather, it is the utterance of a fine, upstanding, context-free referring term.

But now a question: How do we know that utterances of "now" in English are utterances of an indexical? Why not analyze utterances of "now" in English precisely the way utterances of "fow" are to be analyzed in L2? There are, I submit, no facts of linguistic practice (normative or not) that allow us to distinguish between English's "now" and L2's "fow". If linguistic facts supervene on facts of linguistic practice, there is no fact of the matter whether an utterance of "now" should be read as an indexical whose type is identified by the phonemes or as a non-indexical whose type is partly identified by the phonemes and partly by the time of utterance.

If we understand "now" along the lines of "fow", then any argument for the A-Theory of time based on our use of "now" is likely going to fail. For "fow" is perfectly at home in the eternalist world of the B-Theory. And what I said about "now" goes for tenses as well.

This strategy is closely parallel to the old failed B-theoretic attempt to translate "now" into the time of utterance. That attempt failed because when one translated "It is now 11:56 am", it translated into "It is 11:56 am at 11:55 am", and hence a sentence that one could reasonably be wrong about got translated into one that no one could be reasonably wrong about, which is absurd. On the present strategy, an utterance of "now" at 11:56 am does refer to the 11:56 am, indeed is rather like a proper name for it. In a sense "It is now 11:56 am" may be a tautology, but it is not a trivial tautology. Rather, it is like "Cicero is Tully" or "London is Londres."

If all this is right, then no deep facts about language hang on the distinction between indexicals and non-indexicals. There may be more than one way of classifying bits of utterances into types, and for any way of classifying that makes a bit of utterance into a token of an indexical, there is a way of classifying that makes that bit of utterance into a token of a non-indexical identified in some non-phonemic way. Each classification should give rise to the same proposition as expressed by the utterance as a whole.