If you believe the past did exist then you believe it no longer does exist and that it therefore does not exist. — Luke

The past does not exist but it provably did exist (else the present would not exist). From the fact the past did exist and from 'only now exists' we reach 'only now always existed'. Unless you are saying 'only now exists' now but 'only now exists' did not apply at some point in the past. In general, it seems the laws of physics are time independent so it seems an odd stance.

Never heard the term 'presentism.' Does such a thing exist if our biology requires a small lag time in our experience of 'now' in essence turning into 'then?' — julian kroin

Welcome to the forum. Only now is real =presentism is what most people believe I think. Contrast to eternalism (past present and possibly future all real depending on which type of eternalism). I think any biological delay in sensing now does not rule out presentism.

have this thought; entropy explains everything (though I 'm not privy to that explanation) — julian kroin

You are referring to the question of whether entropy is a result of time or time is a result of entropy? I tend to think the first; entropy is a result of cause and effect which is a result of time.

The low entropy of the universe points to a start of time which would rule out presentism.

The low entropy of the universe points to a start of time which would rule out presentism. — Devans99

I suspect that for you, the fact that elephants have tusks...or oak trees grow from acorns...points to a start of time.

"A start of time" is an essential to where you want to go. By now, you should be able to see that...and you should be able to see the influence that predicament presents to clear thinking on the issue.

That aside, however, whence cometh "the low entropy of the universe?"

What is "low" entropy for a universe?

What is "high" entropy for a universe?

What is a moderate...or average...entropy for a universe?

And how did you calculate all this?

It is a fact that entropy increases with time so with infinite time we should have maximum entropy. We are clearly not at maximum entropy; the universe is very organised.

It is possible that entropy 'resets' somehow (eg a Big Crunch) so these types of infinite time models cannot be ruled out with the entropy argument.

"A start of time" is an essential to where you want to go — Frank Apisa

It's more I'm after the truth than I want to go in a specific direction: the weight of evidence seems to point to a start of time.

The past does not exist but it provably did exist (else the present would not exist). — Devans99

Let''s say I don't accept your assertion that the present would not exist unless the past did exist. How are you going to prove that?

From the fact the past did exist and from 'only now exists' we reach 'only now always existed'. — Devans99

"Only now always existed" is grammatically incorrect and incoherent, combining both present and past tenses.. It attempts to refer to a past tense existence of the present moment ("existed"). The present moment does not exist in the past, by definition.

Let''s say I don't accept your assertion that the present would not exist unless the past did exist. How are you going to prove that? — Luke

I think you could say that every effect in the present has a cause in the past else it would not exist so therefore the past must have existed.

"Only now always existed" is grammatically incorrect and incoherent, combining both present and past tenses.. It attempts to refer to a past tense existence of the present moment ("existed"). The present moment does not exist in the past, by definition. — Luke

Point taken. What I mean is: does the state 'only now exists' apply to the past, IE did 'only then exist' in the past if you see what I mean. Because if 'only now exists' applies to all time then there cannot be a start of time (because that would be creation from nothing).

I think you could say that every effect in the present has a cause in the past else it would not exist so therefore the past must have existed. — Devans99

That's just repeating the same assertion. It's not proof.

What I mean is: does the state 'only now exists' apply to the past, IE did 'only then exist' in the past if you see what I mean. Because if 'only now exists' applies to all time then there cannot be a start of time (because that would be creation from nothing). — Devans99

Presentists don't need to accept the assumption about past existence - it's not part of presentism.

That's just repeating the same assertion. It's not proof — Luke

1. The effect is in the present
2. The cause must exist
3. The cause must come prior to the effect
4. So 'prior to now' must have existed.

Presentists don't need to accept the assumption about past existence - it's not part of presentism — Luke

I think thats a debatable statement, see here for example:

https://plato.stanford.edu/entries/presentism/

1. The effect is in the present
2. The cause must exist
3. The cause must come prior to the effect
4. So 'prior to now' must have existed. — Devans99

I don't see that presentists need to make any commitments regarding cause and effect. Again, it's not a part of presentism. But what I had in mind was along the lines of David Hume's views on causation: that assumptions of cause and effect between two events are not necessarily real or true

I think thats a debatable statement, see here for example: — Devans99

Which part?

I've quoted the relevant part below:

The ontological doctrine, P, requires supplementation. Consider, for example, a possible world, w, at which the growing block theory of time is true. At the first moment of w, P is true. There exists only the first moment and that moment is present; there are no other moments, and so the past hasn’t yet come to exist. Later on, it will become clear that w isn’t a presentist world, even though it seems initially to satisfy P: at the first moment, only present things exist. For this reason, when being more forthcoming with a definition of their view, moving beyond mere slogan, presentism might more perspicuously be rendered as a view that is always true, if true at all (Crisp 2003: 215, 2004: 19, fn.6, 2007: 107, n.1). So, presentism amounts to the claim that:

(PA) Always, only present things exist.

*(Infinity is a concept not a number, proof: Infinity, if a number, would be a number X which is greater than all other numbers. But X+1>X). — Devans99

At best this could be an argument that infinity is not an integer.

At best this could be an argument that infinity is not an integer. — Banno

Or a rational, real, complex, vector, matrix... not any sort of number or quantity. Infinity is a concept only and a flawed, inconsistent concept at that.

You're not exactly a mathematical traditionalist.

You might be right; if we throw out transfinite mathematics your arguments might be interesting.

But why should we throw out transfinite mathematics? Because you say so? I'm not convinced.

Maybe you are brilliant. Maybe you are a crackpot. Who's to tell?

I'd argue that a reasonable definition of infinity is: 'something larger than anything else' so that precludes the existence of more than one infinity and therefore we can write:

∞+1=∞
implies
1=0

Which is not a promising start for transfinite mathematics.

Even if you hold to multiple infinities, there is something deeply wrong with:

∞+1=∞

In english, it says there is a thing that when we change it, it does not change. This does not make logical sense.

It seems to me that you just do not have a good grasp of the mathematics of infinity.

On that basis alone, I don't see why one ought listen to your arguments about infinity.

What mistake did I make?

In rejecting Hilbert's hotel, you rejected the mathematics of infinities.

Hence, you make errors such as

∞+1=∞
implies
1=0 — Devans99

I explained above that I believe there is only one type of infinity so therefore it is OK to take ∞ from both sides of an equation.

there is only one type of infinity — Devans99

But we know there are infinite infinities.

What you believe is irrelevant.

That flies in the face of the definition of infinity as the biggest thing ever. You cannot have more than one biggest thing ever.

The multiple infinities appear as a result of the questionable bijection procedure. Any method of comparison that claims the naturals and rationals are the same size is clearly marsh gas.

That flies in the face of the definition of infinity as the biggest thing ever. — Devans99

Cool. That shows that you are working with an unhelpful definition of infinity. Treat it rather as an unbounded number larger than any real number.

I am under the impression that those who discount presentism do so, because they interpret presentism as a variant of realism about time and causality, where the ontological basis of that temporal realism is the present.

But if so, this is a strawman argument, for there is no indication that presentists are realist about time and causality. I think that a presentist can interpret any statement presently, including any statement asserting temporal realism and eternalism. So in some sense I think the presentist would find debates about presentism pointless. For he would interpret both sides of the debate as a construction of the present.

Cool. That shows that you are working with an unhelpful definition of infinity. Treat it rather as an unbounded number larger than any real number. — Banno

No such number exists (as proved above).

What exactly is an 'unbounded number' anyway? Numbers have fixed values; that's why they are numbers; that's their defining characteristic... they are not variables.

So one of the (many) problems with infinity is that it's of no fixed value. That plays havoc with maths and logic. How can you have a number without a fixed value?

It is like in logic, if in addition to 'true' and 'false' I introduced a 3rd truth value of no fixed value, say 'true-and-false'. Now almost everywhere I use the 3rd truth value, I would introduce ambiguity, much to logic's detriment. Infinity damages maths like a 3rd truth value in logic would.

sime
289
I am under the impression that those who discount presentism do so, because they interpret presentism as a variant of realism about time and causality, where the ontological basis of that temporal realism is the present. — sime

I suspect you are making a mistake with that impression, Sime.

I suspect some people, like Devans for example, do it in quest of a goal that must be reachedfor some reason.

In Devans case, I think the goal is to get to, "There is a GOD."

He seems to be doing it by pretending not to be attempting to get there.

He is saying that he just wants to get to "The universe is a creation." (One avenue is by discounting presentism...which he considers proof that "the universe" is not eternal/infinite...and therefore (?) is a creation.

From that, he will extrapolate that there has to be a creator...and from that, I expect he is heading for an Aquinas close of, "And that 'creator' all people call God."

I may be wrong, but if there were a way to obtain the truth on the matter, I would bet huge bucks on it.

You might find this an interesting read: http://fas-philosophy.rutgers.edu/zimmerman/privilegedpresent.pdf

Interesting. It is the case that presentism agrees with our gut feeling about the way the world works I grant. At the same time it seems to be logically impossible (not addressed by the link you gave me). I think time, as demonstrated in relativity, is not intuitive, so trusting to gut feeling might lead us astray.

I think the only precedent for time we have is space. Thats the only other dimension. In space, 'left' and 'right' are real just as 'here' is real.

I think the author's defense of common sense was the weakest part of the article, honestly. While the gut instinct is our best starting point for most ideas, it shouldn't be our final destination.

Time is one of the few philosophical concepts I have no real opinion about. I'm not sure if the past exists or the future, but I guess I do think NOW exists.

If you're interested in more reading, this young man has an interesting approach as well:
https://www.academia.edu/25441363/TIME_TARRIETH_NO_MAN_Presentism_and_the_Argument_from_Relativity

After reading that I wonder if it's possible that time can stretch and therefore make presentism compatible with relativity theory.

(PA) Always, only present things exist. — Devans99

What do you take this to mean? I'm unclear on what the "always" is supposed to add.

I note that the author uses an example wherein time has a beginning, but this is only to illustrate his point. The author is not making a case for a beginning of time.

Anyway, I think the statement (PA) is true from the presentist perspective but false from the eternalist perspective (with or without the "always"). Therefore, I'm still none the wiser about why you think presentists need to hold beliefs or make assumptions about past existence.

What do you take this to mean? — Luke

The fact that the present only exists has ALWAYS been the case. So as we go back in time, still only the present exists. So the present ALWAYS existed. That implies no start of time.

Then if there was a start of time; that would be creation ex nihilo of a sort - creation without time itself which seems impossible (note if there was a 2nd time we would just end up in a infinite regress of time so its fundamental / base reality time I'm talking about).

So as we go back in time, still only the present exists. — Devans99

I'm pretty sure that is called going into the past.

So the present ALWAYS existed. That implies no start of time. — Devans99

If you say so.

Then if there was a start of time; that would be creation ex nihilo of a sort - creation without time itself which seems impossible — Devans99

I guess that also rules out your creator of time then...?