When I say that a thing is identical to itself I mean that it is identical in every way. The DNA strands of twins are not identical in every way - to say the least, they have different positions in spacetime, which makes them different things. — litewave

I didn't say 'strand'. The DNA of twins is identical, consisting only of information, not particular details of a strand, which has properties like position.

OK, how about the candle? Are the two states not the same candle because of the differences in lit and burnt-out, or are they one thing, identical to itself, just extended in spacetime? Even the latter has a hard time with identity if you consider MW cloning. The statement "candle is lit at time T" has no truth value if all those states are part of one identity, and only some of those states are 'lit'.

Not sure why we're nailing down the usage of identical in this topic.

There are some things you could try if you get stuck: — Srap Tasmaner

Linguistic ascent is the worst. Not looking for how existence is used in our language. Almost all the confusion in philosophy, especially in forum discussions, seems partially rooted in language use, which takes far too much for granted.
Transcendental: I'm not asking if anything is the case. Everybody thinks I'm looking for proof or evidence of something.
The theory crafting is perhaps a way of wording part of what I am doing.

As for going over this over a week, sure. Years actually, but it only recently got stuck on this point. I have a pretty good story that is self-consistent as any I've seen, and solves almost all the hard questions, at least to my satisfaction. Fermi paradox is one of the things that is yielded a coherent answer. But part of my supposedly consistent story is flippant use of the word 'exists', so I'm trying to pin that down.

I perhaps claim to have an answer, which I rate still very low on a probability of being THE answer. Everybody has a different opinion, and the odds of mine being the closest guess to the fact of the matter is still very low odds.

So in pondering the question "why is there something instead of nothing", I instead ask how the experience would be different if there were not anything, and found it to be the same. Instantiation is not required. But that answer leans heavily on what it means for something to just be.

I don't think FOL has anything to say about ontology. Not sure where that discussion is intended to go. ∃ means something other than an ontological assertion.

I guess we can agree that every thing that exists must satisfy the criterion of logical consistency: it must be what it is and not be what it is not. In other words, it must be identical to itself and different from what it is not. — litewave

This doesn't help if something is logically consistent but nonexistent. I questioned that above when I cannot come up with an example of a consistent thing that nevertheless is known not to exist.

About identical, the word is ambiguous. Twins share identical (indistinguishable) DNA but are not the same person. A lit candle seems to share numeric identity with the burnt out stub an hour later. It is the same candle (identical), but the two states are hardly indistinguishable.

Say what it means. I cannot read the notation.
For some x, Fx is true. Not sure what the a is.
It being a rule of first order logic doesn't tell me what it means that something (my context universe in particular) exists.

Truth is that which can be shown to be the case.
To show that 'Unicorns have four legs' is true, we need to verify it. — Owen

This topic is not about demonstrating existence, or worse, defining existence in terms of demonstrability, which reduces to idealism.

If you can prove unicorns exist by saying they have four legs, you know you've done something wrong. — Srap Tasmaner

Kind of followed by my understanding of the last line of Owen's post. So perhaps I misunderstood. I'm trying to get a clarification. Maybe the four-leggedness is not true of unicorns because they would first need to exist to have the four legs, but then the reasoning is circular and meaningless.

Remember, I'm not trying to prove anything exists. I am trying to nail down what we're claiming if we claim something exists or not. My shabby attempt of that is "is present in a context", and no, counting legs does not prove presence in whatever context in which we might claim unicorns exist.

So having four legs is something true of unicorns, therefore unicorns exist.

I actually am not far from that logic, but I wanted to make sure you're saying that. It also seems to leave open the obvious paradox of one truth about a nonexistent thing is that it is nonexistent, thus proving its existence.

x exists =def (some F)(Fx). — Owen

But what is (some F)? Perhaps I am just behind in translation of predicate notation. The F seems to be the context, and I have no problem with the statement when there is a context involved. Maybe I'm reading it wrong.

Gave all this several more days to work it over. Had to get this one out of the way:

'I think, therefore I'm possible' is a tautology.

1. I think, therefore I am. — Owen

Well, I am not willing to accept this, so hardly tautological. Even Descartes went only so far as something like "thinking, therefore existence" without immediately being so bold as to fit an "I" into that picture. But I'm questioning what it means to exist, so such axioms cannot be held if they rely on what I'm trying to define.

Possibility exists and therefore actuality can exist. — schopenhauer1

Maybe they're the same thing.
Despite my discarding objective existence based on possibility (due to inability to think of anything objectively impossible), I wondered if there is a distinction between 'possible' and 'real'. There is an epistemological difference, but seemingly not an ontological one.
For example, take again my context of the prime numbers. Eleven is a real prime, and twelve is not. The number of grains of sand on Earth is a potential prime with some significantly low probability. It is impossible to count them, but assuming we had a hard definition of what it means to be counted or not (we most certainly don't), the resulting number would in fact be a prime or not, with no probability about it.
Hence my questioning possible things. If something is possible in some context, it exists. If it doesn't exist in that context, it isn't possible. Can I defend that? I couldn't think of a counter-example. It doesn't work without 'context'. Objective existence is without context, and without context, existence is undefined, and possibility has no impossibility with which to distinguish itself.

Where does that leave me? Thinking, therefore existing in the context of this universe, but no requirement that the universe be real in a context that excludes impossible ones. There does seem to be a deeper context, but it seems that such regression is finite. No turtles all the way down. There is a context that is the entire structure, and it seems not to be a meaningful thing to apply the label 'exists' to that context.

The antinatalist must be pretty happy. There are billions of non-actualized potential people for every actualized one.

I thought of a better word than 'set' or 'structure'. Streetlight brought it up in the causation thread, and it is simply 'context'. A thing is actual or not within a context. There seems to be no context in which a universe is actual but distinguished from another one that is not, unless the context is 'things created by some creator external to the created thing, in which case said creator is just part of a larger context.

It doesn't much give me the answers I seek, but the word seems to better express the question a bit at least.

How would you address this reasoning?: The background to the sum of all existents either exists or does not. If it exists in some way, it is contained within the sum of all existents. If it doesn’t exist in some way, then there is no background to the sum of all existents. Both conclusions result in there not being a background to the sum of all existents, aka to existence. — javra

Seems like pretty good reasoning at first glance, an argument for a lack of distinction.
But can we apply this logic to a horse? Against what background does the actual horse stand apart if the background doesn't exist? I pick horse because it might stand out against the nonexistent (in this world) unicorn. Does the unicorn need to be actual enough for the horse to stand apart from it, in which case the contradiction is unavoidable.
We need to find logic that works for the horse (an example we believe to understand a bit more clearly) before attempting to apply it elsewhere.

Actuality is a property of a temporal tulip object. The universe cannot be actual in this way.
— noAxioms

I think the following supports this quoted conclusion:

Looking at things from a solely physical perspective, the Big Bang is inferred to have resulted from a volume-less gravitational singularity (both space and time began with the Big Bang, so, before the Big Bang there was no space: the gravitational singularity is then volume-less, or space-less [as well as timeless; a different issue though] … hence neither incredibly small nor incredibly big, for both these are contingent upon the existence of space). The more mainstream of modern physics—excluding suppositions such as those of QM MW and M-theory—infers the "Boundless" in the physical form (if it can be termed “form”) of a gravitational singularity. There’s lots of evidence for the Big Bang, and all this evidence points to a volume-less state of being that preceded it (in which all the energy of the universe was contained).

I would say space and time are bounded by the big bang, avoiding the 'before the big bang' reference you use above, a conflicting implication of a time before time. Similarly space, which cannot be a prerequiste. Choose your model. Empty space existing until stuff bangs into it, or space and time being bounded. The two models don't mix kindly. The former requires creation: a cause of sorts. Inflation theory fits the bill at least for a cause, if not the preexisting space and time. The inflation concept of time does not map to the time measured by clocks here, and the theory does not posit space into which stuff exploded.

This volume-less gravitational singularity, then, does not exist in the manner that a tulip does. Yet, assuming it to be objectively real, it nevertheless is (or was), thereby physically existing in a manner other than the physical existence of a tulip.

The singularity qualifies as an event, and events exist sort of in the way the tulip does (the tulip is multiple events, grouped together by language). The universe is not just that one event.

I’m far less confident in upholding what I’ve heard from documentaries about the known universe of today (sorry, I don’t recall which documentaries): that the universe is inferred to have no center and no circumference.

Funny, since I cannot conceive of one with a location in space that is the center. Such a picture would mean there's an edge to it with the fastest moving stuff, and if you were there, you'd see stars only on one side, making it pretty easy to point to said center. If spacetime is modeled in 4D, the center is in that 4th direction, which is arbitrary, but they all point to the same place. I guess we just view the geometry differently.

Nevertheless, were this to be objectively real, the same roundabout issue of existence would apply to the physical universe as it is today: there is distance from one tulip to another, or from one galaxy to another, but there is no distance regarding the whole. If so the universe (as everything that is) physically exists in a manner other than that in which any physical item exists as a part of the universe.

Didn't quite understand this part. If you're saying that our universe doesn't have a location in relation to other universes, they I'd agree. For the record, I don't use the word 'universe' as 'all there is'. It is quite context dependent, and, and for the purpose of this discussion, it means all there is in this grand ball of quantum-mechanical structure, bounded by a bang on one end. Otherwise the question of the existence of other-universes is meaningless, being a question of if there is another all-there-is. A more confined definition of universe would be 'all that matters', which is a more idealistic notion since it implies all that matters to us. This perhaps excludes the past which cannot be affected, the future which cannot be sensed, things that are currently not-here, which is inaccessible in both ways, and places simply beyond our reach even over time, for whatever reason.


And thanks for the feedback javra. I may not agree with everything, but I've already identified some bad ideas I had in need of reconsideration. I need these critiques.

You are in a universe where contingent and determined forces play out perhaps from an original apeiron of boundless and indefinite possibilities which was broken in an original asymmetry which allowed for yet more asymmetries into the universe or multiverse we reside. — schopenhauer1

OK, I seem to be one post behind all the time.
Yes, within this universe, contingent forces play out the possibilities into actualities. Hence a tulip is actual, but that is merely a property of this universe: of the temporal relations between states, and the interpretation of the differences in states between various points, as 'becoming' or actuality. A tulip is is interpreted as an object in a temporal container, and all such objects are rightly interpreted as being caused. The temptation is to generalize the universe itself as such an object that has temporal existence (or existence at all), or that it 'became' at all. I find that view quite naive since I have found no evidence to support it. Hence my labelling it a category error. Actuality is a property of a temporal tulip object. The universe cannot be actual in this way.

This problem goes back to the first philosopher, Anaximander actually. He thought all was undefined or Boundless. Essentially, it was the idea that all was potential with no actuality to it (no form). — schopenhauer1

Sounds pretty clean to me.

Of course, how it goes from boundless to boundaries or undefined to defined from the very start, is anyone's guess.

This presumes that it does 'go from undefined to defined', which seems contradictory since it would imply states and time are defined before anything is defined. Isn't potential enough?

I think, therefore I'm possible. Ewww, but maybe...
— noAxioms

Can you explain this more? — schopenhauer1

Hard to. The set of possible structures, which seems strange without a set of rules about why one might not be possible. The set of structures resulting from consistent application of rules. Closer maybe, but a set of rules can be arbitrarily complex and thus technically rule out almost nothing.

We don't have a grand-unified field theory, but I had heard that we expect it all to be fairly simple in the end and "fit on a T-shirt". A limited number of fundamental components and their relational rules. But without a cap on said rules, there seems to be no limit to what is possible. So: a universe just like this one, but with the addition that Latin invokes magic if you have the right DNA. Same T-shirt, but with a little extra stuff printed on the sleeves.

In the end, I don't think there is a set of existing things. I think 'existence' is misapplied. The cosmological argument questions the how of the existence of the universe, or more naively, how it was 'caused', but the universe seems not to be in need of either causation or existence. There is no set, and I exist in the universe despite the lack of meaning to the concept of the existence of the universe.

So what's the next move? How could you define U in a way that does some work? — Srap Tasmaner

It seems I misinterpreted your meaning of U. You define it (tentatively) as everything that exists in the sort of way I am seeking, not as 'our universe' which is just the chunk of spacetime to which I have access and includes "all the stuff I see and can imply from it".
Taking your definition of U, your statement above is just restating the problem in my OP. Our universe is presumed to 'exist', and not just by being a member of itself. I'm asking what that means. I'm questioning that it means anything at all.

Yeah, I don't understand the significance of being a member of some set. If some means any, then anything you can name is a member of any number of sets. If it is some particular set, then the burden of definition is shifted to defining that set.
— SophistiCat

That last bit was where I was headed. Would have been clearer if I had said "a special set, let's call it U." That's what noAxioms seemed to want to do, and I was just helping him along, as it turns out, mistakenly. — Srap Tasmaner

Yes, I can name any number of sets, but I don't think my naming a set is what makes the universe exist.

Yes, a special set. A distinguishing rule.

OK, per hypothesis, there would be a (Many-Worlds) quantum world where a real Harry Potter exists as well as the Harry Potter fictional stories in our quantum world. Similarly, there would be fictional stories in Harry's world that just so happens to describe our world.

In this case it would be true to say (justification aside) that Harry Potter existed somewhere in the universe, though not in our quantum world. We would just need to be careful to keep our claims about the real Harry Potter in the other world distinct from claims about the fictional Harry Potter in our world. Similarly for Harry's claims about us. — Andrew M

Agree with pretty much all of this, but since these quantum worlds are part the one structure (our spacetime), they're really another part of the same universe, just like another planet, sufficiently distant to be completely out of our empirical reach. The existence of alternate worlds is using 'existence' the way we do with tulips: another part of U. This is opposed to the typical language usage of the word which implies part of the world that to which we have access.

So when I assert that unicorns exist, now, on earth, I am speaking of the simple form of existence but extending my definition of 'earth' to include all the inaccessible quantum versions of earth. It seems improbable that such a creature did not evolve in some of those worlds.

Now about the sort of existence that I am talking about: Our spacetime seems possibly to be one of many bubbles of ordinary physics that condenses (?) out of inflation-stuff, all according to inflation theory. In that sense, our spacetime is just one of those bubbles, and thus is just an object of sorts in a strange collection of related but very different bubbles. The cosmologists are working on the nature of that inflation stuff. There seems to be time there, but not time that maps to ours. The bubbles all obey quantum physics and are effectively related even if they cannot interact. They are objects, not true universes. The inflation stuff seems to be the universe (unless there is even more regress), but if there is a bottom to the regression, what sort of ontological statement can be made about that fundamental universe?

This delineation, however, does a disservice to the form of realism that noAxioms wants to uphold: one that does away with all possible notions of idealism. Because this definition of U depends on awareness in order to hold, it opens doors to idealistic notions. — javra

Wanting to uphold that is well and nice, but so many paths keep coming back to the idealism for which I express my distaste. So in the interest of not caving to my biases, I have to give that consideration.

It could help out to better pinpoint what is intended by the term “existence”. For example, as mentioned in Wikipedia, existence can be classified into the “wide” and the “narrow” sense. In the wide sense of existence, anything that holds any type of being (or presence) can be stated to exist. Figments of the imagination, such as fictional characters, then exist in the wide sense. In the narrow sense, only that which pertains to objective reality (but see the aforementioned for different approaches to what this could imply) can be stated to exist. Harry Potter, then, does not exist in the narrow sense.[/quote]All these are the the same class to me. They are objects, things, representations, relations, whatever, within their universes. None are the universe itself, something that is not a member of some more general structure. So some might classify a relation like velocity to be something that exists, and others else might not. I'm not too concerned with that. What does 'existence' mean to a universe whose full description defines defines that velocity?

Then questions can be posed such as the following: does QM MW exist in the narrow sense, or only in the wide sense?

MW is a strange case, and it seems more a question of if that interpretation is in fact the correct one or not. If that interpretation is correct, then there are certainly other worlds and they are certainly observed, some of them at least. They're really all just other places, all part of one universe actually, and thus fail to be an example of the sort of existence I seek.

Some might say there is no fact of the matter (QM interpretation), but I don't think that fact is beyond investigation. They're attempting to build a quantum computer, which means money is being put behind one interpretation over the other, and that money would be wasted if there was no way to empirically falsify something like hidden-state interpretation.

As a related example, existence could either entail the set of “that which is distinguishable from some background” (this being in line with the literal translation of “standing out”) or the set of “that which holds any sort of presence” (e.g., hypothesizing the Buddhist notion of Nirvana, the state of Nirvana would only exist in the latter sense and not the former). The universe—here presuming it equivalent with everything that exists in the wide sense—can be argued to not exist in the first sense just mentioned: it has no background against which it can be distinguished.

Well, it's that background I'm seeking I think. I'm not so sure about a necessary lack of one.

This conception of the universe, then, can be argued to exist only in the second sense just mentioned. To me this implies that U can exist only as a member of itself. The only way I can find to avoid this conclusion is to grant existence in the wide sense a background of nothingness (also in the wide sense)—but, then, it seems that this would endow nothingness in the wide sense with substantial presence: thereby making nothingness too an aspect of existence in the wide sense. Hence, again leading to the conclusion that set U can exist only as a member of itself.

But I didn't like the second-sense, finding it pretty much the same as the first sense. No, U would not be a member of itself, but it would be a member of something that includes other <need a noun here>'s which also distinguish themselves from whatever background we might identify. I think it presumptuous to select a noun there with the distinction left undefined. I tried 'structure', but not sure if other members that stand out are necessarily structures.

javra, getting to yours. I too have finite time to digest it all.

In terms of antinatalism, it is interesting to know that you need existence to know that non-existence is preferable. — schopenhauer1

Wrong kind of existence, but I see what you're saying. Given the right kind of existence, I'm not convinced that the logic here applies. I exist (wrong kind) in this universe, but this universe seems not to need to exist (right kind) in order for its occupants (us) to know that existence is preferable. Absent a distinction somewhere, the 'right kind' of existence cannot have relevance. Humans instinctually consider the universe to have properties of other objects with which we are familiar, such as a tulip, and thus requires coming into existence, and perhaps sharing existence with other existing things but not with the nonexistent ones. I recognized that misapplication of instinct, and am trying to build it back up on more solid footing.

[/quote]However, non-existence does not seem like something that can exist in and of itself. So, how can anything be purely non-existence by itself without an existence to compare it to?[/quote]It would seem to be a property, no? There can be no pure-warm property without a thing to which the property can be applied (a lit candle say), and something other thing with which to contrast it (un-lit candle). I can do this with objects. A tulip exists in my yard, and the pink elephant does not. Hmm, my logic sort of fails, since the pink elephant seems to need to exist at least so far as to permit the application the property of nonexistence.

Existence entails non-existence but non-existence itself does not seem to make sense. Perhaps non-existence is pure possibility without being actualized? Then again, what is pure possibility as that seems to be "something" and thus has an existence.

You're going down the same path I see. The pink elephant is for whatever reason possible, and hence can have the property of nonexistence. What doesn't get that far? Maybe what makes the pink elephant possible (but not actual) is what makes our universe distinct from one that is not possible.
I think, therefore I'm possible. Ewww, but maybe...

Science tells us that the universe existed for eons without us, but its existence was meaningless without us, we assert meaning into an indifferent universe. — Cavacava

Science might say that events (things, matter, whatever) existed in the universe for eons without us, but it does not offer an opinion on the philosophical topic on the table here. I'm asking if there is an objective fact-of-the matter, independent of our ability to find meaning in it, or our ability to detect it.

When we say that Harry Potter can point to stuff, we are making a different kind of claim to when we say that we can point to stuff. The latter is understood in a straightforward literal sense, the former assumes we are talking about a work of fiction. That is, our interpretation of those claims already depend on us making a distinction between what exists and what is mere representation. That distinction is enough to provide a usage for the word "exists". — Andrew M

OK, the Harry Potter stories (be they conveyed in books, films, plays, whatever) are representations, all forms of language, allowing us to share a vision Rowling's alternate world in our minds. The 'real' world can similarly be said to work the same way. The senses we take in are just different languages, letting us create a model of the world in which the characters in the model point to things. We presume in the direct-sense way that the story our senses tell us are real, that the characters 'exist'. No proof of this exists, but it degenerates into solipsism to assume otherwise. With fiction, there is no such assumption. The world depicted is perhaps a real one, the London/England we know, but an alternate world in which perhaps some quantum collapse back a thousand years unlocked some new gene in a subset of humans that unlocked access to what us muggles would consider supernatural powers, invoked with Latin utterances apparently. The Harry in that world (completely inaccessible to us) can point to stuff, and his ability to do so does not demonstrate (to what??) that world's existence.

Similarly, perhaps our world is a fictional one depicted in stories in Harry's world. There can be no test of it, but I was wondering if it was meaningful to ask what it would mean, without asking to what it would be meaningful to.

You mention that you are not confused about the difference between the two. But whether Harry Potter is confused is only a question of whether the author represents him as confused or not.

The representation is only that, I admit.

So you want set and set membership to be the starting point, and to define existence in terms of those. Something exists if it is a member of some special set U. — Srap Tasmaner

No, the U is arbitrary, and usually means all that stuff I see, and all the rest that is implied by it. The far side of the moon exists despite the lack of its direct accessibility to any of my five senses.

What I am questioning in this thread is what distinguishes U itself from existing or not, especially absent a member-observer being aware of some portion of the contents of the U. Not asking why U exists and certainly not how it 'became to exist', but what it means at all. Is there an objective fact to the matter, despite the lack of anything that can actually know said objective fact?

I looked up all sorts of articles from the various philosophers, and they seem more concerned with what classes of things exist, and which are excluded. Does love exist? Depends who you ask. But nobody seems to address what it means to exist in the first place, at least not in a way that can be applied to our universe itself. So quantum MW interpretation says there is another universe with an earth where life never began. Assuming the MW interpretation is correct (is there an objective correct answer???), does such an alternative world exist? The only distinguishing difference would be the absence of observers on Earth, and it would seem to be idealism to suggest that what makes this world exist but not that one.

Per realism, that we can observe or point to something is not what makes that thing exist (which is a separate question), but it is what allows us to claim that it exists. We aren't confused about the ontological difference between our universe and the Harry Potter universe because we can point to the books and the author from where those ideas derive and we understand their history. — Andrew M

I want to agree, but I think where I differ is the claim. If this universe did not exist, I would still be able to point to it. I would just not exist along with it. The universe existing seems not to be a prerequisite to its occupant pointing to it. Harry Potter can point to stuff in his universe despite both their nonexistence. I'm not confused about the difference between the two, but Harry is. Maybe he reads a fiction book about us.

I was thinking:
a) 7 is a number, same as 8. To say 7 is prime or 8 is even is to state some knowledge that describes properties of these numbers. As product of knowledge, what it is to be a prime number, has no effect on their assumed 'ontology' — Cavacava

I am not referring to knowledge of the structure, but rather the objective (independent of knowledge or observation) reality of the structure. Is the structure of the set of primes dependent on knowledge of it? Quite possibly so it seems, even if that makes it an idealistic distinction, But seven being a prime is true regardless of said knowledge.

b) The set of primes is separate from the rest of the sets of numbers, yet what it excludes both limits it and helps define the set.

Point taken. The structure of whole numbers would need to exist to give meaning to the primes and the numbers that are not. The primes exist as part of that set, and that set part of rational numbers and so forth in a sort of heirarchy of supersets. Is there a bottom to that? Is our universe just a member of (an actuality in) some larger structure of things (like inflation bubbles for instance)? My question still stands then about that superset, unless there is no bottom to the regression.

c) To say the universe is this or that, is not viciously circular, since we have no independent viewpoint.

Hence my choice of a structure other than this universe we know. I am not a member of that structure (I am not a prime), so I have sort of an independent viewpoint of it. Similarly, inflation theory posits all these different universes with different tunings of the various cosmological constants, and in almost all of them, they have the wrong number of macro dimensions or wrong forces for anything coherent like matter to form. They cannot be observed, do not exist in any sense of the term 'now', yet it would seem to be a violation of consistency for them not to share our own ontological status.

Is this about existential quantification?

If so, then to exist is to be an element in the domain of discourse; roughly, to exist is to be spoken of. — Banno

I had not meant it to be about existential quantification, but my attempts to sort this out come to this quite a bit: I have a base aversion to idealism, so I stay away from statements implying observation or discourse being the thing distinguishing an objectively actual structure (maybe that's a better word than 'set') from a non-actual one. But it comes up a lot, sort of a circular ontology of mind supervening on the material, but the ontology of the material somehow supervening on that observation.
Sorry about that statement. I can barely parse it myself. Language fails me trying to express this issue.

Russell's paradoxes show the deficiencies of set theoretical interpretations of first order schemes.

I should give em a look.

How could any entity that was actually actual - ie: a materially individuated form - not be individuated within a world. Where would this material thing be? How could it be considered individuated except by virtue of a context of all that which it is not? — apokrisis

I'm talking about what makes the world actual, not some member of it. And I'm certainly not talking about 'material things', which is just how things manifest themselves to us in this particular world.

What distinguishes and actual world from a potential one? Even a potential world is individuated by virtue of what it is not, so individuation seems not to be the distinction.

↪noAxioms If we are talking about actual things in a world then the essential difference is that the possible forms are materialised. We are speaking of substantial being. — apokrisis

You miss my point. I am not talking about things that are actual in a world (or more plainly, are members of the set of things in that world/universe/container), I am talking about things that are actual period. What does it mean, ontologically, that that container itself is actualized, and not just potential. Let's assume it is not a container/universe to which we have access, to prevent idealism from defining its actuality. So not asking how we could know it is actualized, just what the actualization would mean to the set in question of which the actual-things are members.

It would be usual to distinguish between every thing potential and every thing actual. — apokrisis

So what would it mean for something to be 'actual'? I could think of no objective way to frame that answer. Best I could do is "the thing is a member of set such and such". The set of all existing (actual) things is a circular definition, and thus useless. The set of all sets is similarly without distinction of any kind.

So for instance, Earth is a member of the set of physical objects in the universe of which we are aware. I don't want to take the idealistic stance and say that Earth's existence is dependent on our awareness of it, but without the reference point of our awareness, in what way can it be said that Earth is 'actual'?

There is doubt, therefore the doubt is actual. Really? How would the same doubt be any different if it was merely potential?

We can test the term by attempting to find a particular that fits into the category of the term that everyone agrees with, and another particular that fits outside the category. — Samuel Lacrampe

Wait, everybody has to agree with it? Don't remember that being a requirement. I have personally found some math problems to be cute, and I can find an exception to the hamster thing as well, even if I'm not that exception.

Anyway, you seem to be driving for the language definition of 'life' (or the language 'essence' of anything else), which is pretty easy since there is but one example, and you're related to it or not. The way the word is used in common language is of no use when trying to decide if something new is life or not.

Perhaps it is because of weight of evidence for the other side as well, and your refusal to acknowledge that.

Nevertheless, it seems that our views often not held because of rational reasoning. I personally have found some of my own biases well grounded, despite 'knowing' that they are false. I continue to hold to them. But at least I stopped rationalizing them.

Better example: A hamster is cute. A math exam is not. Therefore the essence of 'cute' exists. — Samuel Lacrampe

So what is the essence of 'essence'? What doesn't have essence?
You just seems to be asserting that every adjective or noun in the language has an essence, and the proof you give is needless given that assertion.

Not quite. From the point of view of special relativity, as analysed with respect to an inertial frame, only the scalar speed along the tangent of the trajectory, and not the acceleration, is relevant to the ratio of time dilation of a moving clock. — Pierre-Normand

Yes, but look at it from the perspective of the edge. According to SR, a clock on the edge, in its own frame, is stationary and thus runs faster, not slower, than the moving clock at the center. But that frame is not maintained for even a moment, so SR doesn't really apply. The change of reference frame, and thus the change of the instant with which the center-clock is simultaneous, is what makes the center clock steadily gain time, not lose it. The effect is a moment-of-acceleration thing: acceleration component multiplied by the distance of the reference object in the direction of said acceleration component.

I had written an example once of time dilation (twins-experiment, sort of) that involved no acceleration or gravity, and hence needed to invoke only SR rules. Despite a clock in an unpowered ship being stationary in its own frame, it shows how the sum of the times for a trip log less cumulative time than a moving clock that is always running slower. I could post that if you're interested. I cannot illustrate the disk thing with just SR since the edge clocks never maintain any particular IRF.

Isn't linear speed synonymous to tangential speed in this case? I'm not convinced that the spatial distance between the clocks located away from the centre of the disk would change considering that we don't even know whether the disk itself is Born rigid. — TimeLine

Yes, linear speed (in the frame of center) is tangential speed and is constant, and the spatial distance from the center is fixed, since they're all welded to this disk and have really no choice about it. The radius should remain constant for the duration of the experiment.

The clock nearest the disk center will most closely match the reference clock since it is pretty much stationary. Time dilation has nothing to do with rotational speed. The ones at the edge will have the least elapsed time because those are accelerating the most.

This experiment has already been done, using Earth as the disk.

What would you say any of this implies about how spacetime is structured and how I should know which frame is at rest? — JulianMau

There is no such thing as 'the frame that is at rest'.

More interesting: If the disk is manufactured already spinning and infinitely rigid, spatial dilation will occur at the edges, so the circumference of the disk would be more than Pi times the radius. The disk cannot slow down because that would change the circumference, and that cannot happen due to it being infinitely rigid. So it can't stop. Unlimited energy source! Of course this only illustrates the absurdity of positing an infinitely rigid thing.

Being able to remember and recognize red sounds like knowledge. We do use know to mean experiential in addition to propositional knowledge. — Marchesk

I also found that solution to be thin. I did not gain knowledge that Atlanta is the capitol of Georgia, I just gained the skill of remembering it.

However, any theory of mind which allows for multiple realizability seems to be perfectly compatible with the notion that particular mental states tightly correlate with particular physical states (by supervenience, emergence, or whatever), and that said mental states could also be realized in another medium. — Arkady

I was thinking of the identity of those mental states. I feel like I have a persistent identity (being the same person I was a minute ago, despite a different physical state back then, and being the same person I was when I was 4, despite a nearly complete lack of the original matter of which I was then composed). So how am I not already swampman? What has happened in that thought-experiment that has not happened to me? All that's missing is an unverifiable causal connection between the one version of 'me' and the present state.

A putative observer introduces a point of reference, with respect to which some predicates will differ, e.g. left/right. — SophistiCat

There seems to be no distinction between left and right. If there were, the universe would not be symmetrical. Hard to imagine that, but would there be some sort of inability to count the spheres without breaking the symmetry, and thus actually making two distinct spheres? The definition says they're one thing, and I cannot find a way to dispute that.

Is this true, though? A person may possibly believe that mental states, while themselves immaterial, nevertheless supervene on physical states (or are otherwise emergent from them). In that case, the physical duplicate would still possess the same mental states. — Arkady

I think that anybody that expects to take their memories (and thus any sort of identity at all) into what they hope to be an afterlife cannot take a stance of memory supervening on physical states. Claims of OoB experiences rest on memory and sensory input operating independently of the physical apparatus of brain and sense organs. The world (thing in itself) is really how it appears experientially. Anyway, a person holding to such beliefs might suggest a fundamental difference between swampman and his original. The thought-experiment suggests no answer to the question.

Perhaps a sort of thoroughgoing substance dualist might deny that there is any connection between the mental and the physical, but I don't see how that view can be plausibly maintained once we accept some basic metaphysical assumptions (e.g. that there are material bodies) and scientific observations (e.g. that memories are neurologically encoded in the brain in some fashion, by long-term potentiation or whatever the exact mechanism is, and mental states at the very least correlate in some fashion with the physical state of one's brain).

I hear ya.

As to plausibility:
To scan a person exactly would violate Heisenberg's uncertainty principle. Matter can be (and has been) teleported, but not scanned for copying. On the other, the copy probably doesn't need to be exact to the quantum level. Any arrangement of molecules in the same places would suffice, so the molecular 3D printer at sufficient granularity to make an indistinguishable copy is not a violation of physics.

That said, everybody takes their own answers into the swampman story, so the thought experiment doesn't really illustrate anything. Arkady: You assume an exact physical copy would have all the memories, as do I, but somebody that argues for memory being part of immaterial state would disagree. So the thought experiment fails to resolve the issue for which it was posited.

That doesn't mean there is no use for thought-experiments. Some eventually suggest empirical tests, and others simply don't apply to humans, but do apply to other beings. What is it like to be cloned? Humans have no memory of it, and I can't ask the things that are. Our society and law is based heavily on the assumption that it cannot be done, or at least cannot be remembered. So I rely on thought experiments to work out the alternate rules, until I find consistent answers.