Peter Unger on the Emptiness of the Present-Eternalist Debate

Peter Unger doubts, with respect to the past, but not with respect to the future, whether there is any “concretely substantial difference” between presentism and eternalism (Empty Ideas, Oxford UP, 2014, 176 ff.). He argues that any appearance of a substantial difference is “illusory.” Both parties agree on such contingent past-tensed truths as that dinosaurs once roamed the earth. They agree that there are such truths about the past whether we know them or not. The parties to the dispute further agree that these truths are fixed and determinate, and as such unalterable. To employ one of Unger's examples, was Abe Lincoln as a boy ever friends with a boy named 'David'? According to Unger, he either was or was not, and there is a fact of the matter one way or the other. No matter that we don't know which. Unger: “. . . our Presentist and our Eternalist will agree that 'what's past is already fixed and determined; it's a done deal which cannot possible be undone.” (2014, 177) In sum, both parties to the controversy agree that there are truths about the past; that some of them are known to be true; that these truths, whether known or not, form a complete set; and that these truths cannot be changed.

Unger's point is that presentist and eternalist differ only in the ways they talk and think about the collection of agreed-upon Moorean facts. The eternalist, but not the presentist, will say that dinosaurs tenselessly exist and tenselessly roam the earth at times millions of years earlier than the time at which the eternalist speaks, etc. The presentist, but not the eternalist, will just use ordinary English with its tenses: dinosaurs don't exist now, but they used to exist millions of years ago, and when they existed they roamed the earth, etc. There is no “concretely substantial difference” between what the presentist holds and what the eternalist holds with respect to the past. (2014, 178) Their disagreement is trivial and insubstantial because they differ merely on how to talk about a body of agreed-upon facts.

But this can't be right since, while there is much that presentists and eternalists agree on, there are substantive points of disagreements that divide them. Unger says on behalf of the presentist that “a tenseless way of talking and thinking will have us (at least tend to) 'spatialize time,' thus (tending to make or) making obscure to us the dynamic aspect of concrete reality . . . .” (2014, 177, emphasis in original). Right here Unger himself unwittingly points to a substantive disagreement that divides presentists and eternalists, or at least those (the majority) of the latter who are B-eternalists. Is there a dynamic aspect of concrete reality? Surely it is a substantive question whether concrete, mind-independent reality is static or dynamic. If real time is exhausted by the B-series, then B-eternalism advocates a static view of time and change unacceptable to presentists.

It surely seems that the following related questions are also substantive: Is temporal passage real or is it mind-dependent? Is time a fourth dimension of a four-dimensional manifold, space-time, which features time as its fourth dimension? Is the existence of temporal items independent of when they exist, or does the existence of such items depend on when they exist? Is existence reducible to temporal presentness, or not? Are the truths about the past on which presentists and eternalists agree brute truths or are they truths grounded in items external to the truths? Suppose we pursue the last question.

Presentist and eternalist agree on the contingent truth that Socrates existed but does not now exist. What is this truth about? The natural answer is that it is about Socrates. The presentist, however, for whom only the present exists, cannot avail himself of this natural answer. For if present items alone exist, then Socrates does not exist in which case he cannot be referred to: the reference relation is such that, necessarily, if a name refers to, or is about, a thing, then the thing exists. The presentist has to say, implausibly, that 'Socrates' is about something else such as Socrates' haecceity, or else that the name is not about anything, and that therefore the truth in question is a brute truth. To say that it is a brute truth is to say that it is just true! When he was alive, the present-tensed 'Socrates exists,' or rather the proposition expressed by the Greek equivalent, was about Socrates, and true in virtue of Socrates' existence, but after he ceased to exist, 'Socrates existed,' which became true on Socrates' demise, is not about him. That is surely strange.

The eternalist, recoiling in disgust, will say that the truth that Socrates existed is about Socrates who exists tenselessly at (some but not all of the) times earlier than the time of this observation, and that, therefore, the truth in question is not a brute truth, but one grounded in the (tenseless) existence of Socrates. Whatever the merits of the competing views, we certainly seem to have here a substantive disagreement, one that pivots on the question whether singular, affirmative truths about merely past items need truth-makers or truth-grounds. Maybe they do; maybe they don't. Either way, this is not a dispute about different ways of talking and thinking about some agreed-upon collection of Moorean facts.

Unger also says on behalf of the presentist that

. . . there aren't any such tenseless senses of, or forms of, 'exist' and 'be,' and any other naturally available constructions featuring verbs. . . . when it is said that two and three make five, the only real sense of that is the same as the single sense of what's stated when it's said that two and three now make five. . . . So, properly, we should say that two and three always did make five, and they now do make five, and they always will make five. (2014, 176-7.)

But here too there are points of substantive disagreement. It is a substantive question whether or not numbers are timeless entities. Suppose they are. Then the copula in '7 is prime' will have to be tenseless. Talk about the timeless is tenseless. Since it is a substantive question whether there are timeless items, it is a substantive question whether there are tenseless senses of 'exist' and 'be.' Suppose I say to my class, “David Hume is an empiricist who believes that every significant idea is traceable to a corresponding sensory impression.” It is an interesting substantive question whether the verb forms in this sentence are tenseless or tensed.

Comments

[David Gudeman]

"Surely it is a substantive question whether concrete, mind-independent reality is static or dynamic."

I find this very doubtful. The same sorts of argument can be used here: that any differences are merely linguistic in character. I started to right out the details, but it became too long, so I posted a blog entry: https://brainlegions.wordpress.com/2019/09/11/it-is-a-substantive-question-whether-time-is-static-or-dynamic/

[David Gudeman]

I just thought of a brief way to express my reasons for doubting that there is a substantial matter of fact about whether the A-theory or the B-theory of time is correct. The problem is that there is a logical, necessary relationship between the two theories such that if one theory is true then the other theory is true. They are just two different ways of visualizing or thinking about the same basic facts.