Two kinds of change

I ran across this old post of mine and it made me think that there is an interesting distinction between two kinds of change which one might label as objectual and factual change. Objectual change is change in objects, including both an object’s acquiring or losing properties and an object’s coming or ceasing to be. Factual change is change in reality itself—the facts of reality themselves change, with future facts coming to be present (and on open future views getting filled out) and present facts coming to be past. We can put this in terms of change of facts, change of truth value of (“fully closed”) propositions, or change of reality as a whole.

When A-theorists accuse B-theorists of having a static picture of the universe and B-theorists respond with the at-at theory of change (change is a thing’s having a property at one time and lacking it at another), they are talking past each other to some degree. The A-theorist is talking of factual change. The B-theorist is talking of objectual change. The A-theorist is simply right that on the B-theory there is no factual change: the facts about reality were, are and will ever be the same. That there is objectual change on the B-theory does not contradict this. But at the same time, the A-theorist’s accusation of static factuality is something the B-theorist should proudly admit as a feature and not a bug: truth does not change.

That there is objectual change is a part of our uncontroversial data about the world. That there is factual change is the A-theory in a nutshell, and hence begs the question against the B-theorist.

At this point it seems we have an impasse. Where should the debate go? I think one thing to figure out is whether one of the kinds of change depends on the other. Suppose it turns out that objectual change would need to depend on factual change. Then the A-theorist has won: the B-theory has no change at all. Note that the at-at theory of change is not a sufficient response to a claim that objectual change depends on factual change. For the at-at theory depends on the concept of time (change is having different properties at different times), and if time itself requires factual change, then the at-at theory itself requires the A-theory. This suggests that if the at-at theory is going to be the B-theorist’s response, the B-theorist owes the A-theorist an account of what makes time be time (McTaggart insisted on the latter point).

What about the other direction? That one is kind of interesting, too. One might think that factual change would need to arise from objectual change. Aristotle apparently did. It’s not clear, however, how one gets the A-theorist’s change of reality, where future facts become present and present facts become past, out of changes in objects. Perhaps one can read McTaggart’s infamous argument against the coherence of the A-theory as an attempt to show that this task can’t be done, at least in the special case where the objects are events.

Can we offer such an argument? Maybe. We aren’t going to be able to get factual change simply from the fact that objects have different ordinary properties at different times, say a light being green at t₁, orange at t₂, and red at t₃. For there is no way to use such facts to ground which of these times are past, present or future. So it seems that if we’re to get factual change from objectual change, we’re going to have go the route McTaggart suggests, and try to ground it in terms of objects’ temporal A-properties, say this light’s being past, present, or future. But that seems problematic. For the change between past, present and future does not happen in the lifetime of the light. During the lifetime of the light, the light is always present—it is only past after its existence and it is only future before its existence! But a change that does not happen during an object’s lifetime is, of course, a Cambridge change, like a horse’s becoming posthumously famous. And Cambridge change must always be relative to something else changing really. But then it is in the latter change that we should be grounding our factual change. And now we are off on a vicious regress, much as McTaggart (perhaps for somewhat different reasons) thought.

This suggests to me that just as the B-theorist denies that objectual change depends on factual change, the A-theorist should deny that factual change arises from objectual change. As more than one philosopher has noted, the A-theorist should respond to McTaggart by taking A-temporality, understood as factual change, as primitive.

The evanescent world of becoming

An old idea in philosophy, going back to Plato, is that things that are becoming are less beings than things that are timeless. This is a mysterious view, but I have just found that my own preferred four-dimensionalism implies a clear and unmysterious version of this view.

On my preferred four-dimensionalism, material substances are four-dimensional entities. Since they are substances, they are explanatorily prior to any parts or accidents they may have. This four-dimensionalism, thus, cannot hold that four-dimensional entities are constructed out of three-dimensional time slices, or even that the slices are somehow ontologically on par with the four-dimensional substances.

Nonetheless, it makes sense to talk of a three-dimensional time slices as a kind of derivative entity.

It may, for instance, turn out to be like the Thomist’s “virtual entities”. The Thomist does not think that the electrons that help make up my body are substances, but thinks that our scientific language can be saved: the electrons “virtually exist” in virtue of my pattern of (accidental) causal powers.

Or it might even be that three-dimensional time slices just are accidents: that the four-dimensional entity that I am has an accident corresponding to every time at which it exists, an accident which itself is the bearer of further accidents. Thus, the fact that I have a certain three-dimensional shape s at a time t could be analyzed in terms of me having an existence-at-t accident E_t, and E_t in turn having an s-shape accident.

Virtual entities and accidents are unmysteriously less beings than substances: for them to be is to qualify a substance.

So, now, here is a reconstruction of the Platonic insight. A lot of our ordinary talk about material substances is most straightforwardly construed as about time slices rather than four-dimensional substances. When we talk of the shape of a flower, we mean its three-dimensional shape with respect to a particular slice, and so on. Now, we identify something like the Platonic world of becoming as the world of three-dimensional time slices. These are completely evanescent entities—they exist literally only for a moment each—and their being is derivative from the being of substances.

Presentists have long complained that four-dimensional entities are not really becoming. We can embrace an aspect of that insight. There is a way in which the four-dimensional entities form a world where time is less important. Granted, they indeed are spatio temporal entities: they do exist in time as well as in space. But there is little reason to think that their very being is somehow ontologically tied to time in the way that the presenists think the world of becoming is. On the other hand, the time slices are very much time slices: their very being is tied to their temporality.

Of course, this reconstruction of the Platonic insight into a world of becoming is in the end quite unfaithful to Plato: for we, who are four-dimensional substances, end up not being in the world of becoming, though we ground it. We are almost like Kantian noumena, grounding a world of becoming phenomena.

I don't know that the standard presentist can reconstruct the Platonist insight. For the standard presentist, to be is to be at present. The only difference between eternal things and things in the world of becoming is that eternal things were and will be in the same state, while things in the world of becoming were and/or will be in a different state. This is not a difference with respect to a way of being.

Time is not the measure of change or animals are not essentially temporal

Imagine that beings like us come into existence at the very first moment of time and they are the only contingent beings. To aid imagination, suppose we are these beings, and it is now the very first moment of time. Then, barring divine promises or other such divine moral considerations, it is possible that both (a) we won’t exist at any point of the future, and (b) it’s not the case that anything else will come into existence. Thus:

1. It is possible that the only contingent beings there are are human-like beings and that contingent beings exist at one and only one moment.

But:

2. Change requires at least two moments of time.

Putting all of the above together, we get:

3. Either (a) human-like beings can exist without time or (b) time does not require change or (c) time cannot have a beginning or (d) time cannot have an end.

I think theists are likely to deny both 3c and 3d: God can create and terminate a timeline. That leaves the theist 3a and 3b. I think both 3a and 3b are plausible moves.

Aristotle famously held that time depends on change, but he thought that time couldn’t have a beginning or an end, and thus he accepted both 3c and 3d. The argument he actually gave for 3c and 3d doesn’t work (basically, it fails to distinguish “not was” from “was not” and “not will” from “will not”), but we can now see that there actually is a plausible Aristotelian reason to accept that time can’t have a beginning or an end if we think time is the measure of change.

Why am I talking of human-like beings rather than human beings? Well, maybe, “human being” is a biological kind, and biological kinds depend on evolutionary history, so maybe it is not possible for human beings to come into existence at the first moment of time, as they wouldn’t have an evolutionary history. But beings just like humans could.

Becoming

A-theorists talk of something called "becoming" which they say B-theorists have no room for. I don't really understand what this is. I am inclined to say that

1. x becomes F if and only if there is a time at which x is non-F and a later time at which x is F.

If so, then there is becoming—-indeed, objective becoming—-on the B-theory. Now, I think most A-theorists will agree that (1) is a necessary truth. So where's the disagreement on becoming?

Maybe, the disagreement lies in this. Although (1) is a necessary truth, nonetheless becoming is something more than just being non-F and later being F. This "something more" is necessarily there whenever something is earlier non-F and later F, but it is nonetheless something extra. (Just as God's knowing that the sky is blue is something more than just the sky being blue, but that "something more" is always there whenever the sky is blue, since God knows that the sky is blue necessarily if and only if the sky is blue.) But I really don't know what this "something more" is. I feel here like van Inwagen on substitutional quantification.

Well, that's not quite right. For it may be that (1) isn't exactly right. Suppose x has gappy existence. It exists from morning until noon and then from dinner until midnight. From morning until noon x is non-F and from dinner until midnight x is F. Does x become F? I could imagine someone saying "No" (and indeed a colleague did say just that). If not, then (1) may not be right.

Maybe one thinks gappy existence is impossible. (But why not? It seems no harder than being a spatially scattered individual, and if we're made of precisely located particles, which sure seems comprehensible, we're that.) But then consider this case. At every time that (in some unit system) is an irrational number, x is non-F and at every time that is a rational number, x is F. Then x satisfies (1). But does x ever become F? If so, when? At any time at which it is F, it also was F at an infinite number of earlier but arbitrarily close times. (This argument requires time to be a continuum, which I fear it's not.)

So one might question (1), though I am happy to bite the bullet in both cases. Maybe one should insist that to become F, you need to be non-F over an interval of times and be F over a succeeding interval of times, or something like that. But such modifications are neutral between the A- and B-theories.

Perhaps, though, the A-theorist's insistence on becoming is not so much about objects becoming a certain way, as about truths changing. The B-theorist is committed to propositions not changing in truth value. Many (but not all) A-theorists think propositions change in truth value. Thus,

2. There is becoming if and only if there is a proposition p that is true at one time and not true at another.

The B-theorist will then reject that there is becoming in this way. But notice that no it no longer seems appropriate to speak, as some A-theorists do, of doing justice to our "experience of becoming." For while we may experience the sky turning from blue to purple, we do not experience, except in a very theory-dependent way, the proposition <The sky is blue> turning from true to false. That's a change (though presumably a Cambridge one) in a Platonic entity.