Hence the question in the OP might become "Why is the empty possible world not the actual world?"

And the answer is, it just isn't. — Banno

From a modal realist perspective like mine, "actual" is indexical, so that question in turn becomes "why aren't we in the empty possibly world?" The answer to which, of course, is that any world that we are in is by definition not empty; we can only find ourselves in a world that contains at least ourselves.

We might then ask why there is anything besides ourselves in this world, and the answer to that would concern the prevalence of possible worlds that just contain (basically) a Boltzmann Brain compared to worlds containing complex cosmological and evolutionary processes that give rise to brains in the way we suppose ours were created. Which pretty much reduces this problem to the Boltzmann brain problem.

But the question is not "why are we not in the empty possible world?".

If the question is why the empty world is not the actual world, then the question IS why we are not in it, at least to a modal realist like me, to whom “the actual world” means “the world we are in” and nothing more.

...that would imply that Pforrest exists in every possible world.


SO much for your version of modal realism.

...no? Not sure where you're getting that from.

There are possible worlds without me in them, and possible worlds with some alternate version of me in them but not this me. Those are not the actual world to me, though they are actual to anyone in them. Just like there were times when I didn't exist, and times with some earlier version of me in them but not this me, and those are not the present to me, but they are present to anyone in them.

Questions like why something such as X exists seem reasonable based on phenomenon we observe around us. Like we know from experience that it makes sense to ask why does this table exist. We can describe economic phenomenon, or the scientific components of the table, that resulted in this table. From these kinds of experiences, we formulated a vocabulary that helps describe things. The history of science in turn has given us insights into what kind of questions can be formulated correctly and how they can be confirmed when it comes to more complicated phenomenon. Not every formulated question is a good one, bad questions don't reciprocate actual answers. That really depends on how things in the world actually works, and we just have to take it as it is.

So far from what we can tell, there isn't any reason to believe that this vocabulary can be used to describe why does "anything at all" exists. Like what standard (what collection of experiences that inform judgment) can be used to differentiate between one state of affairs where the world that we know of is the way it is, and where none of this applies. There is no way to formulate and apply such standards, in the way we can use science and economics to explain tables. And if we don't have the set of experiences where we can make the necessary judgments, there isn't any reason to suppose the question itself is a meaningful one.

My own guess is further insight into cosmological questions will dramatically alter our notions of causality and temporality, so progress on judging the meaningfulness of the question can be shaved down without experimentation indirectly from tuning our vocabulary.

Why are there discussions on this topic instead of not discussions on this topic?

There is no possible world at which there is no world, therefore the existence of something is logically necessary. — Pfhorrest

From a modal realist perspective like mine, "actual" is indexical, so that question in turn becomes "why aren't we in the empty possibly world?" — Pfhorrest

What’s the difference between an empty possible world and “no world”?

There are possible worlds without me in them, and possible worlds with some alternate version of me in them but not this me. Those are not the actual world to me, though they are actual to anyone in them. Just like there were times when I didn't exist, and times with some earlier version of me in them but not this me, and those are not the present to me, but they are present to anyone in them. — Pfhorrest

A “possible world” is therefore a spacetime snapshot of this or some other (possible) world?

What’s the difference between an empty possible world and “no world”? — Luke

Imagine a building with infinite rooms (a Hilbert Hotel if you will) representing the set of all possible worlds. An empty possible world is represented by a room with nothing in it. An absence of any possible world is not represented; there is no room for it.

A “possible world” is therefore a spacetime snapshot of this or some other (possible) world? — Luke

That depends on who you ask. In my version of modal realism, which seems to also be similar to Saul Kripke's (though I'm not super well-versed in Kripke), that's more or less correct; on my account, another time literally is the same thing as another possible world that meets certain criteria in relation to the present/the actual world. But on David Lewis' account, he being the premier promoter of modal realism, possible worlds are complete spacetimes, with pasts and futures of their own, not just snapshots. I guess I'm kinda weird for combining a (probably) Kripke-like conception of possible worlds with a Lewis-like realism about them.

"You are a fluke of the universe, you have no right to be here."

That is a parodist response to the Desiderata, which "argues" that a person has reason to think otherwise.

The question has the quality of asking for comfort in a hostile place. I would like to take my very existence as proof of something but existence keeps suggesting I should stop that.

I am grass, trying to stay out of range of the lawnmower.

Imagine a building with infinite rooms (a Hilbert Hotel if you will) representing the set of all possible worlds. — Pfhorrest

So there is something rather than nothing because of the postulated existence of this building with infinite rooms...

An empty possible world is represented by a room with nothing in it. An absence of any possible world is not represented; there is no room for it. — Pfhorrest

So the absence of a possible world is impossible, even if that possible world is absent... :chin:

So there is something rather than nothing because of the postulated existence of this building with infinite rooms... — Luke

No, the building is just an illustration, a metaphor.

There is a world at all because there not being a world at all is not a possibility. At every possible world (whatever that means) there is some world.

There is something in the particular world that you are in because a world with you in it is a world with something in it: you.

Why is there anything else in that same world as you? :shrug:

No, the building is just an illustration, a metaphor. — Pfhorrest

It seems to be much more than that given that it’s the reason you have offered for why it is logically impossible for there to be no world. The existence of possible worlds is why you say there cannot be nothing, even if one (or more) of those possible worlds is empty.

But there is a possible world that is empty. — Banno

Interesting approach. I guess it's the fastest and shortest route the the heart of the issue.

Stupidity is, as my link points out, a congenital species defect which intellience struggles with / against and occasionally exploits (e.g. pioneers, explorers, thrill-junkies, young parents ...) — 180 Proof

Nice! A great way to look at the things - how intelligence operates at another level and "...occasionally exploits..." stupidity.

There could be no non-existent world even if modal realism were false; that why I said in my last post “whatever that means” about possible worlds.

There could also be an empty world in any case, whatever it means for there to “be a possible world” in each different interpretation of modality.

The appeal to modal realism is only involved in the question of why there’s a non-empty one instead of an empty one, for on a modal realist account all possible worlds equally exist in the same way, so if there could be an empty world, there is; it’s just not THIS one. The reason it’s not this one is, for starters, because we’re here, making it non-empty.

Then the reason you have offered for why there is something instead of nothing amounts to little more than: because there is something. But I don’t wish to suggest there’s a better response.

There could be no non-existent world even if modal realism were false — Pfhorrest

Sorry, I overlooked this. Why couldn’t there be a non-existent world (i.e. why couldn’t there be nothing) even if modal realism were false?

Why couldn’t there be a non-existent world (i.e. why couldn’t there be nothing) even if modal realism were false? — Luke

Because there is no possible world at which there is no world, regardless of what it means for there to “be a possible world”.

This is going to escalate quickly to the point where writing post becomes more trouble than it is worth, but I will have another go at cleaning up the discussion.

Firstly, logic should be philosophically neutral. It is about syntactical rules and their interpretation; it's just grammar. It can tell us how we might join proper names and predicates and logical connectives and quantifiers together, but it can't tell us what the proper names and predicates stand for.

So if someone were to show up here claiming to have a modal argument for the existence of god, I'd take a lot of convincing. Logic can tell us what to say about such-and-such once we know it exists; but it cannot bring things into existence.

So I was both impressed and sceptical when @Pfhorrest suggested the argument "There is no possible world at which there is no world, therefore the existence of something is logically necessary". It seems to show that something must exist.

"There is no possible world at which there is no world" looks a bit like slight-of-hand. It's not a neat parsing of "There is something rather than nothing". Things are within worlds, so "There is something" is talking about what is happening within some possible world, not about there being a word. Hence, we might better parse "Why is there something rather than nothing" as asking if there is a possible world that contains nothing.

And here we set off into free modal logic - and into considerable complexity. The upshot here is that so far as I am aware there is nothing preventing a possible world with an empty domain. It's odd, but ask a silly question...

Another approach, which @Pfhorrest might have at the back of his mind in talking of "indexical" modal realism, is asking if we can access an empty possible world. As it stands the argument he presented only says that we cannot be in an empty possible world, which is obvious, and unhelpful since it tells us nothing about a possible world that it empty of even us.

Because there is no possible world at which there is no world, regardless of what it means for there to “be a possible world”. — Pfhorrest

Seems to me you are confusing there being no world with there being an empty world.

Then the reason you have offered for why there is something instead of nothing amounts to little more than: because there is something. — Luke

Yep.

As a (hardcore) actualist rather than possibilist, or modal realist, by "a possible world" I understand a possible version of actuality (i.e. a possible way the actual world could have been or can be described), such that "actual" is not an index for any "possible world" at issue but rather is the extant domain, or universe, of possibilities (à la phase-space).

Thus, I transpose @Pfhorrest's possibilist/modal realist statement as 'there is no possible version of the actual world which could have been ... non-actual world (aka "nothing")'. Your contention, Banno, about an "empty world" is, to my mind, a possible way the actual world could have been; however, "empty world" – whether in actualist or possibilist semantics – cannot be, as you seem to suggest, "empty" of "being a world", that is, "an empty world" which is also "not a world" – a contradiction.

If you like. For my money actualists take existence too seriously. I don't have much of a problem with quantifying over fictional characters, for example: "There is at least one hobbit who walked into Moria" does not commit me to there actually being hobbits.

I don't see a reasonable way of distinguishing a possible version of the actual world from any possible world.So not sure what you are getting at there. The empty world is a possible world and hence a possible way the actual world might have been.

It's sufficient for the purposes of this thread that some doubt be cast on there being a clear understanding of "There is no possible world at which there is no world".

For my money actualists take existence too seriously. — Banno

Well, sir, we actualist hobbits surely don't (and certainly not before second breakfast & a full pipe). :yum:

Because there is no possible world at which there is no world, regardless of what it means for there to “be a possible world”. — Pfhorrest

Interesting. A world in which nothing exists wouldn't be a world let alone a possible world. Perhaps we shouldn't bring up the notion of "possible worlds" as "worlds" becomes a source of confusion because it's a loaded term - comes with ontological baggage so to speak.

Seems to me you are confusing there being no world with there being an empty world. — Banno

I was interpreting "there being nothing" as "there being no world" at first, but when you brought up the possibility of there being an empty world, I thereafter distinguished between them. But in the bit you replied to, I was replying to this:

Why couldn’t there be a non-existent world (i.e. why couldn’t there be nothing) — Luke

Which sounds like Luke is asking not about an empty world, but about there being no world ("a non-existent world"). Maybe he is confusing the two?

My stance toward non-existent worlds remains the same (there logically must be some world, there don't exist any non-existent worlds, whatever it means for a "possible world" to "exist"), but I've since clarified that I think yes, empty worlds are totally logically possible (and so on a modal realist account like mine, exist), although it's of course not possible that we could exist in one, because our existing in one would make it non-empty. But at some possible world there "is nothing", sure. It's just not this one, not the least because we're here.

if we can access an empty possible world — Banno

If I understand Kripkean accessibility relationships correctly (and I'm not highly confident that I do), that's basically asking if this world we're in could possibly evolve into an empty state.



I'm not sure about that question, but as I understand the current state of physics, true vacuum is thought to be basically impossible, so completely emptying this world (or a world enough like it) is not physically possible.

However, almost all of the complete universe (if eternal inflation is correct) is pretty much as close to empty as could possibly be: all but (an infinite number of) tiny finite pockets of stuff (like our observable universe) is just space filled only with vacuum energy, expanding as rapidly as it can. Rarely, but in that infinite universe consequently all the time, a tiny bit of it slows down a little, which collapses the adjacent parts as well, and the bits next to them, and so on at the speed of light, all of that former expansion energy converting into enormous amounts of other forms of energy -- a Big Bang -- but the rest of the universe beyond that pocket is expanding so much faster that these bubbles remain isolated from each other. If nothing is done to stop it (like somehow harnessing that energy of expansion to preserve a part of the observable universe), everything will eventually expand at an accelerating rate and rejoin the rest of that inflating empty universe. In that way, this world as we know it could get, more or less, emptied; and began empty as well, until it suddenly wasn't.

If I understand Kripkean accessibility relationships correctly (and I'm not highly confident that I do), that's basically asking if this world we're in could possibly evolve into an empty state. — Pfhorrest

I'm not qualified, but from what I understand i don't think that's right. But leave it as moot. I understand possible worlds as constructed by fiat of their proposer; that is, it's the "what if..." that brings 'em into the conversation. Hence, what we can construct from the actual world does not place any limitation on possible worlds. The physics of this world does not limit the possibilities of other worlds.

Hmmm let's not go on such an adventure; nasty, uncomfortable things.

Forgive me for being ignorant but I am just a crayon eating web surfer and am not that book smart.

Does the modal realist perspective consider worlds that have laws that do not follow our own, to be within the set of "possible worlds?" For example, would a world where gravity makes things fall upwards a possible world?

Possible worlds are just "what if..."'s. What if gravity repealed instead of attracted? That's just supposing a possible world in which gravity is repulsive. What if Trump won in 2020? that's just supposing a possible world in which Trump was still president.

This is quite distinct form multiple universes, as proposed by some quantum theories.

It became more interesting to philosophers with a formalisation of the process in Modal logic, developed by Saul Kripke. This formalisation has led to a wide-ranging discussion of what might be possible and what might be necessary.

Possibilities:

1. Something [includes possible worlds]

Or

2. Nothing

Possible worlds:

Any world that doesn't entail a contradiction. Most importantly doesn't include the situation in which nothing exists for if nothing exists, it can't be a world

if nothing exists, it can't be a world — TheMadFool

:up: