Is "presentism" just a proposed redefinition masquerading as a substantive thesis?

Question

Some previous questions here (e.g., How is existence in presentism reconciled with relativity of simultaneity?) asked about apparent conflicts between presentism and special relativity. I have a more general question about the first, which suggests that this conflict is just an instance of a more general problem.

Presentists say, e.g., OPE" "only temporally present things exist." But I've never quite understood what the presentists think that OPE means, or what they want me to believe, in practice, by asserting OPE. I thought this when I first read a defense of their theory 30 years ago, before I began my PhD in philosophy (specializing in ethics rather than metaphysics, to be sure), and nothing I've read or heard since has shed any significant light on it.

The most sense I can make of it is that they think that OPE makes (what to some of us are surprising) assertions about which objects the well-defined word "exists" correctly refers to...whereas in fact they are surreptitiously re-defining "exists" to refer only to things which are present (and then redefining "present" so that this has nothing to do with physicists' understanding of time, to boot). Well, I guess you can do that if you want to, and then the rest of us (especially those who take physical science seriously) have to translate between their speech and ours. But it's confusing and unproductive, especially if the presentists think they are making more substantive claims when they're not. It's like asking "how many legs does a dog have, if you call a tail a leg?" Well, four, because calling a tail a leg doesn't make it one. I can of course talk your way and say "five," but I don't see the point of doing so, especially if you insist that you aren't redefining "leg" but defending a surprising thesis about what tails are or could be, and you expect me to agree with you about it.

One can defend presentism via the "intuition" that what exists, is just what exists now. But then you have paradoxes about how past things can cause present things, which they evidently do, without existing. If you can only defend presentism by abandoning all our intuitions about causation, don't pretend to me that you are defending common-sense intuitions as such--you are instead picking and choosing them arbitrarily. Our intuitions may of course be somewhat confused here; that's why they should generally give way to more precise scientific analyses of reality instead of the other way around. So if causation is real, then there are problems with presentism even under Newtonian conceptions; special relativity just exacerbates these. Ultimately you can go solipsistic and say that only the here-and-now exists, but again if you think this is a substantive claim when you're only (unreasonably) narrowing your conception of "exists," then we'll need a different word to refer to all the stuff (things, entities, moments) around (and before and after) the here-and-now, to serve the same role as the word that the rest of us previously called existents. Indeed, this seems implied by the usual definitions of presentism, as when OPE distinguishes present moments (events, entities, etc.) from, well, presumably non-present ones. Well, ok, then when I want to talk about the latter, give me a more general word than "exists" to do so with, and I'll carry on as before. Now, I'm fine with using more precise notation/terminology if this proves to be necessary, when we discover that the world is more complex than our previous speech/intuitions took it to be. And by no means do I rule out some possible value to presentist talk in this regard; maybe we should distinguish more sharply between present and non-present entities (other than, well, in the way I just did). But my objection is that it hasn't been presented this way, but rather as a substantive thesis about reality, so it is no wonder they haven't so much as presented arguments in favor of a merely pragmatic terminological change, let alone compelling ones.

One professor suggested, in response to my question about what OPE meant in practice, that presentism would forbid quantification over non-present times. But this exemplifies the same problem. Consider NEW: "There was at least one year in the 19th century when no European power was at war." I don't know if NEW is true or not, but it is surely quite meaningful and either true or false (or, if there are ambiguous cases, they may involve having to clarify what we mean by "European power" or "war"--but surely there is little doubt about what we mean by "year in the 19th century"). Now if the presentists don't want us to assert quantified sentences like NEW, they had damned well better give us ways of translating NEW into their preferred terminology. I don't know what that would look like...but I suspect it would just be a more complex, roundabout way of expressing the same proposition I take NEW to express.

So that's my thesis; my question is simply, is this wrong, or it is a plausible reading of the claims and debates over presentism, shedding some light over the issue? Discuss.

Answer 1

You are certainly correct to point out that much of the debate hinges on one's interpretation of the word exist, but that is no different to many other areas of philosophy where different views ultimately boil down to differences in interpretation of language.

As a theoretical physicist, I think there is an important distinction to be made between the past, the present and the future. In that context, it is natural to consider the past as no-longer existing and the future as not yet existing. If you like, you can play around with the words to come up with some other view, but you are just playing around with the words.

It might help to consider how this is modelled in physics. The Universe is taken to exist within a four-dimensional spacetime. You are continually moving through spacetime along a trajectory known as your world-line. The part of spacetime you occupy now is different from the part of spacetime you occupied yesterday and from the part of spacetime you will occupy tomorrow.

Yesterday for you no longer exists in the sense that all of the particles that comprise your body are no longer in that region of spacetime- they have moved forward to today.

The problem with presentism, as it is often explained, is that it assumed you can define the present unambiguously everywhere, whereas 'now', like here', is inherently local.

Answer 2

But then you have paradoxes about how past things can cause present things, which they evidently do, without existing

the past does not exist, but the present is ever-changing, and these changes are not random, therefore the conventional language about "past" states causing the present state, or the past causing the present.

Speaking of yesterday is just a conventional way to speak of a previous configuration of the present.

That being settled, much of your question evaporates.

Answer 3

Taking relativity into account, a person can identify events that are simultaneous to their self, but those events will not necessarily be simultaneous to others. Therefore presentism is relative. The differences do not contradict causality, they are due to causality.

An illustrative scenario : Three astronauts (A, B & C) in deep space moving in different frames: different directions and different velocities. If all the frame details are known, calculations could be made accounting for time dilation etc. so that—with advanced planning—from the perspective of astronaut A all 3 astronauts could snap their fingers in unison. All such events calculated from A's perspective constitute A's presentist manifold of simultaneity.

From the perspectives of astronauts B & C the finger snaps would not be simultaneous. B & C have their own manifolds of simultaneity. Hence presentism is relative.

Edit : On the other hand, if the astronauts maintained clocks synchronised to Earth time by adjustment for time-dilation then they could snap their fingers at 3pm Earth-time and would presumably all be doing so simultaneously.

2nd Edit

Or maybe synchronisation is trickier than that. Either way, if the existence of the present-at-hand is determined in relation to Dasein then each Dasein has their manifold of present existence, whether it is the same or individual to each Dasein. (In this way what exists in not determined from 'the view from nowhere'.)

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Re. OPE ("only temporally present things exist"). This raises the question of the meaning of existence which Heidegger seeks to ground as foundational to science. So existence is pre-scientific, not established by science. Nevertheless, scientific, temporal co-presence (as 'presence-at-hand') is determined by calculations of time dilation etc. which leads to the interesting multiplicity of presentist manifolds.

Basic concepts determine the way in which we get an understanding beforehand of the area of subject-matter underlying all the objects a science takes as its theme, and all positive investigation is guided by this understanding. Only after the area itself has been explored beforehand in a corresponding manner do these concepts become genuinely demon­strated and 'grounded'. GA2 H10

ontology taken in the widest sense without favouring any particular ontological directions or tendencies—requires a further clue. Ontological inquiry is indeed more primordial, as over against the ontical inquiry of the positive sciences. But it remains itself naïve and opaque if in its researches into the Being of entities it fails to discuss the meaning of Being in general. ... The question of Being aims therefore at ascertaining the a priori condi­tions not only for the possibility of the sciences which examine entities as entities of such and such a type, and, in so doing, already operate with an understanding of Being, but also for the possibility of those ontologies themselves which are prior to the ontical sciences and which provide their foundations. GA2 H11

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The type of existence which astronaut A participates in by determining things and events that are co-existent is referred to by Heidegger as presence-at-hand (whether near or remote), so co-present as may be determined by calculation. On the other hand, the ontological existence of astronaut A is described as 'Dasein' and is a different order of existence. The present-at-hand is determined in relation to Dasein.

The 'essence' ["Wesen"] of [Dasein] lies in its "to be" [Zu-sein]. Its Being-what-it-is [Was-sein] (essentia) must, so far as we can speak of it at all, be conceived in terms of its Being (existentia). But here our ontological task is to show that when we choose to designate the Being of this entity as "existence" [Existenz], this term does not and cannot have the ontological signification of the traditional term "existentia"; ontologically, existentia is tantamount to Being-present-at-hand, a kind of Being which is essentially inappropriate to entities of Dasein's character.

... those characteristics which can be exhibited in [Dasein] are not 'properties' present-at-hand of some entity which 'looks' so and so and is itself present-at-hand; they are in each case possible ways for it to be, and no more than that. All the Being-as-it-is [So-sein] which this entity possesses is primarily Being. So when we designate this entity with the term 'Dasein', we are expressing not its "what" (as if it were a table, house or tree) but its Being. GA2 H42

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OP asks : by the usual definitions of presentism, as when OPE distinguishes present moments (events, entities, etc.) from, well, presumably non-present ones. Well, ok, then when I want to talk about the latter, give me a more general word than "exists"

As mentioned above, events co-present to A are not necessarily co-present to B or C, i.e. they may be non-present. In Heideggerian terminology each astronauts' co-present events are present-at-hand relativising presence to Dasein.

If Dasein is excluded from the picture it results in McTaggart's absurd vicious circle which he describes in The Unreality of Time (1908). Note Conifold's comment: "McTaggart was an objective idealist, all subject bound constructs were "unreal" to him."