Einstein seems to answer that the past and future exist as much as the present. If we grant this, then there is nothing mysterious about a specialness to "now" that cannot be explained by science. It is simply an illusion. After all, every single "now" has this apparent specialness. — hypericin

Every single 'now'? Have you ever experienced more than one?

To say "This rock exists" is saying something about the rock. Can this same something be said of the rock of yesterday or tomorrow? — hypericin

To say “This rock exists” is saying something about the rock. But have I said anything less if I just pointed to the rock and said “This rock”. And would I say anything more if I said “This is the rock I stubbed my toe on yesterday and by the way it still exists. You mean now? No, I mean still exists in yesterday.”

This is good example of confusion disguised as deep metaphysical musings.

This rock exists.

To say the same thing is to say this rock exists.

This rock exists cannot be said of the rock of yesterday nor the rock of tomorrow, which is the answer to the question of whether or not it can be said this rock of yesterday or this rock of tomorrow exists.

The me of yesterday can say this rock exists, and the me of tomorrow can say this rock exists, but.....well, that ain’t happenin’, so.....

I am wondering more about what it is saying about the person who says it and in what situation saying it would be of any use. — Fooloso4

.....yep, just like that.

Every single 'now'? Have you ever experienced more than one? — Tate

Of course. Just not simultaneously.

Of course. Just not simultaneously. — hypericin

That's a word game. There's only one now.

There is one now in the sense that there is one north. But just like north points in different directions at different points, different moments of time are christened "now".

I am wondering more about what it is saying about the person who says it and in what situation saying it would be of any use. — Fooloso4

Perhaps teaching the language, or a philosophical discussion: "This rock exists. Dragons do not."
Perhaps there is a situation where some rocks are illusory projections.

This rock exists cannot be said of the rock of yesterday nor the rock of tomorrow, — Mww

No, but you can say, "the rock of yesterday exists", "the rock of tomorrow exists".

The issue cannot be reduced to grammar.

To say “This rock exists” is saying something about the rock. But have I said anything less if I just pointed to the rock and said “This rock”. — Richard B

"This rock" merely points attention to the rock.

And would I say anything more if I said “This is the rock I stubbed my toe on yesterday and by the way it still exists. You mean now? No, I mean still exists in yesterday.” — Richard B

This senselessly attaches a metaphysical claim to a mundane one.

This is good example of confusion disguised as deep metaphysical musings. — Richard B

I make no claim to philosophical depth, but you are the one confused.

There is one now in the sense that there is one north. But just like north points in different directions at different points, different moments of time are christened "now". — hypericin

Is it a matter of christening? Could I christen yesterday at 10:30 pm "now"?

Teacher: This rock exists.

Student: What about that rock?

Teacher: That rock exists.

Student: And these others, do they exist.

Teacher: Yes, all these rocks exist.

Student: Then do all rocks exist?

Teacher: No.

Student: Which rocks don't exist?

Teacher: Um, none of them.

Student: So, all rocks do exist!

Teacher: Er, yes.

Student: Then why are you telling me that this rock exists?

I make no claim to philosophical depth, but you are the one confused — hypericin

It is true, that I am confused - like if someone ask me how many touchdowns were scored in a baseball game.

This rock" merely points attention to the rock. — hypericin

And “This rock exist” does not do the same?

This rock exists cannot be said of the rock of yesterday nor the rock of tomorrow,
— Mww

No, but you can say, "the rock of yesterday exists", "the rock of tomorrow exists". — hypericin

Of course you can; you just did. Nevertheless, the rock of yesterday exists isn’t saying the same as this rock exists.

(Sigh)

The present is 2022 AD. I exist.

We're in the future relative to 1997. I exist.

We're in the past relative to 2060. I exist.

Yep, the past, the present, the future, all, exist!

As per the theory of relativity, there is no one NOW, there are as many of 'em as there are moments, each to be experienced from particular frames of reference.

Consider a loaf of unsliced bread (o, the horror, the horror) as the block universe, a corollary of relativity; each slice is a NOW and you can slice the loaf in any way you wish - if you cut the bread at any angle other than 90_o relative to the length of the bread, you might see a slice of the past or the future relative to the base NOW which is at 90^o to the length of the bread , that would be your NOW. So says Brian Greene. If you disagree, go take it up with him.

The present is 2022 AD. I exist.

We're in the future relative to 1997. I exist.

We're in the past relative to 2060. I exist. — Agent Smith

I think all that was said was that you exist in 2022.

I think all that was said was that you exist in 2022. — Richard B

Ok!

Could I christen yesterday at 10:30 pm "now"? — Tate

In a sense, yes, though I'm not sure it helps with the question at hand.

i think we have three options:
(1) Tensed language centered on our notional now (most common);
(2) Untensed language with "timestamps" or times as parameters (common among scientists and not too uncommon among philosophers);
(3) Tensed language centered on some other time than our notional now (pretty uncommon except for the historical present -- the option you asked about).

You can, to some degree, use these three strategies interchangeably and just translate among them. I think they aren't entirely equivalent though, and it shows up not in the content of propositions but in our attitudes toward them. We do not remember the future, for instance, under any scheme. And speaking yesterday of the rock as it is today was future-tense speculation, but for us, looking at it in the present, it's merely fact. I think there's more to all that, but again I'm not sure it helps at all.

(1) Tensed language centered on our notional now (most common);
(2) Untensed language with "timestamps" or times as parameters (common among scientists and not too uncommon among philosophers);
(3) Tensed language centered on some other time than our notional now (pretty uncommon except for the historical present -- the option you asked about). — Srap Tasmaner

#1 gives us an image of time as something digital, or pulsing. Existence only applies to the present. The past is gone and future is imaginary.

#2 if scientific, time is affected by gravity, or maybe it's an aspect of gravity. There is no universal Now. The content of now, in terms of events, is relative to the observer. I think I have that right.

#3 is a complex use of language where we enter into a faux world.

According to presentism, if we were to make an accurate list of all the things that exist...there would be not a single merely past or merely future object on the list. Thus, you and the Taj Mahal would be on the list, but neither Socrates nor any future Martian outposts would be included. (Assuming, that is, both (i) that each person is identical to his or her body, and (ii) that Socrates’s body ceased to be present—thereby going out of existence, according to presentism—shortly after he died. Those who reject the first of these assumptions should simply replace the examples in this article involving allegedly non-present people with appropriate examples involving the non-present bodies of those people.) And it is not just Socrates and future Martian outposts, either—the same goes for any other putative object that lacks the property of being present. No such objects exist, according to presentism.

There are different ways to oppose presentism—that is, to defend the view that at least some non-present objects exist. One version of non-presentism is eternalism, which says that objects from both the past and the future exist. According to eternalism, non-present objects like Socrates and future Martian outposts exist now, even though they are not currently present. We may not be able to see them at the moment, on this view, and they may not be in the same space-time vicinity that we find ourselves in right now, but they should nevertheless be on the list of all existing things.

It might be objected that there is something odd about attributing to a non-presentist the claim that Socrates exists now, since there is a sense in which that claim is clearly false. In order to forestall this objection, let us distinguish between two senses of “x exists now”. In one sense, which we can call the temporal location sense, this expression is synonymous with “x is present”. The non-presentist will admit that, in the temporal location sense of “x exists now”, it is true that no non-present objects exist now. But in the other sense of “x exists now”, which we can call the ontological sense, to say that “x exists now” is just to say that x is now in the domain of our most unrestricted quantifiers. Using the ontological sense of “exists”, we can talk about something existing in a perfectly general sense, without presupposing anything about its temporal location. When we attribute to non-presentists the claim that non-present objects like Socrates exist right now, we commit non-presentists only to the claim that these non-present objects exist now in the ontological sense (the one involving the most unrestricted quantifiers). — SEP article on Time

To say "This rock exists" is saying something about the rock. Can this same something be said of the rock of yesterday or tomorrow? — hypericin

To say “This rock exists in location X” is saying something about the rock and its location. Can this same something be said of the rock if it is move to location Y and back to location X, does it exist in location Y still?

To say "This rock exists" is saying something about the rock. Can this same something be said of the rock of yesterday or tomorrow? — hypericin

One can certainly say something about the rock in the present, the present being defined as what is happening right now, at this moment, while I am looking, and maybe feeling, the rock. But I cannot say anything with certainty about that rock when the moment passes and the event is something in the past. Much less can I say anything with certainty about what will happen to this rock in the future.

But I don't think that this example reflects your topic: Do the past and future exist?

Anyway, my answer to that question is "No, they don't". Past refers to something that existed or has happened and passed, so it doesn't exist anymore. Future refers to something that has not happened yet, so of course, it doesn’t exist either.

To say "This rock exists" is saying something about the rock. Can this same something be said of the rock of yesterday or tomorrow? — hypericin

To clarify: By "Can this same something" , I was referring to the property of existence, however you define it. I am not asking if precisely the same thing can be said. By trying to sidestep "how do you define existence", it looks like I created more confusion.

Ha!

The future and past are very real. The future, as what will be, is a world of possibility. The past, as what has been, is the world of actuality. The difficult part to understand is the present, the world of change. This is when possibility becomes actual. We know the present is real because change is real, and change only occurs at the present.

Time travel would be impossible if the past and the future didn't exist.

Computer, take me to 10,000 BC

Error! Destination does not exist!

Ok, computer, take me to 2345 AD

Error! Destination does not exist!

Ok, computer, where can you take me?

DOES NOT COMPUTE!

I have a somewhat similar view. I believe the past and future is real, but only by virtue of the present.

The past is not like a museum hall frozen in time. The past is both the progenitor and the imprint on the present. The bite wound on my finger is real, and the event that caused it is real, as it caused and imprinted the present state of my finger, and my memory of it. But as the scar and my memory fades, so does the bite event. In 100 years, the event will have passed from existence.

Similarly, the future is the set of open possibilities which can be arrived at from the present. A future event is real to the extent that it is the likely possibility or range of possibilities. The future event of me sitting in this chair 10 seconds from my typing this sentence is quite real, most paths from the present lead to it. But it is not quite as real as my present state of sitting. Where I will be at this time of day in June is largely undetermined and so has not emerged as real yet. The first thought of my day 20 years from now is barely real yet at all, since it is almost totally unconstrained from this point.

I think the fact that events in the past affect the present, and the events in the present affect the future, should not be confused with either being real.

Neither past nor future is real. If they are real, then where are they?

To say "This rock exists" is saying something about the rock. Can this same something be said of the rock of yesterday or tomorrow? — hypericin

According to theory of relativity, time is a special kind of space. So you could say that the rock of yesterday or tomorrow exists in that space, just in a different location. However we cannot interact with objects in that space like we can with objects in the usual space, so we use past and future tenses of verbs when talking about past and future.

Moreover, even if the implication of relativity is true, that past and future are coequally real with the present, doesn't mean that they are real for us.

Similarly, from the god's eye view, there might be billions of other universes. But their events do not intersect ours, at all, and so from our view, they are not real.

Or, there might be an amazing alien civilization "right now" in another galaxy. But it is strictly inaccessible to us, due to the speed of light we are completely limited to imagining it. "unreal" is what only exists in the imagination, and so this civilization is unreal to us.

If they are real, then where are they? — Tzeentch

The past and future are right here, embodied in the present.
You could not understand yourself without understanding that you were born. Your current state of affairs all flow directly from the event of your birth. Therefore your birth is a real event, you experience it right now, that will have completely passed from existence in a hundred thousand years.