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This is because the concept “nothing” covers all that could possibly be and says “not any of that.”
Please tell me you understand what I’m saying now, even if you think it’s nonsense. 
No. that’s the point. You will have no perspective, you will be nothing, cease to exist, as does the universe for you. If you can accept “nothing” as it pertains to your existence after death then why can’t you accept “nothing” as it pertains to a universe that was never “born”?
They are different because we are here to think about them. Non-existence would have no entities to ponder its non existence.
I can and do accept “nothing” as it pertains to my existence. What I don’t accept is “nothing” as it pertains to “everything”. It’s telling to me that you can’t quite make that first sentence make sense without saying that it is true for a non-existent being.
So if we weren’t here, would Narnia exist in the exact same sense as your “nothing”? How about any fictional kingdoms no-one will ever imagine?
Logically, surely “nothing” is the conceptual opposite of “everything”.
It seems to me that all that you are saying is “I can’t imagine what that means”. But I don’t see how that’s a qualitatively different statement than “I can’t imagine a world without cheese”. Although I grant, of course, that it’s easier to imagine a world without cheese!
The validity of any counterfactual hypothetical seems to me to be entirely dependend upon subjective factors: upon whether a mind has the imagination to carry out the thought experiment; and whether the mind thinks that it is worthwhile to do so.
I still don’t think that you’ve pinned down any objective criterion by which the hypothetical “suppose everything does not exist” is qualitatively different from “suppose cheese does not exist”.
Then what is the conceptual opposite of “thing”?
The descriptor “cheese” does not encompass all that could in principle have a descriptor attached to it. We also know that “no cheese” can be meaningfully said to exist, although that is not the difference I am highlighting here.
Also, I know I started it. Can we stop using cheese as our example? Contemplating a universe without cheese is just depressing.
“Thing” is a word in the English language for an unspecified object. I don’t see the relevance. Are just playing semantic games because “thing” happens to be the end of the word nothing?
It’s pretty clear that “Nothing exists” means “Everything does not exist”.
Cheese, Hitler, physical laws, everything. For all X, where X is unrestricted, X does not exist.
You seem to want to claim that the hypothetical “nothing exists” is intrinsically self-contradictory or something. I just don’t see that. Despite your protestations, I really don’t think there’s any lack of clarity in what it’s intended to mean as a hypothetical, and most people don’t have a problem imagining it, or at least grasping what they are supposed to imagine.
Whether it’s a worthwhile question is a separate matter, of course. It’s certainly not a scientific question.
Not at all. I wanted to avoid what I thought was a potential word game looming. In the case of the sentence you provided, I don’t have any any objection to saying “nothing exists” means “everything does not exist.”
You could also say it means “something doesn’t exist”
It’s not clear to me why you wanted to specify “everything” rather than “things” (a thing, some things, all things, infinite things) was conceptually opposite to nothing. To (grudgingly) go back to cheese. It seems to me the opposite concept of “no cheese” is not “all cheese”, it’s just “cheese.”
Well you’ve accurately summarised my position at least. Yes, that is what I think. Existence is a property. “Nothing” has no properties. I don’t know how else to say it. I don’t agree that people can imagine nothing. I think that people can only imagine things, and when they try to imagine nothing, they imagine a black thing. That’s why I think many of the people disagreeing with me here keep slipping into spacial-temporal language and saying things like “in the void” or “there is more nothing outside the universe”. “Absolute nothing” is distinct from the everyday “nothing” which is simply the absence of any of some possible set of things in some place, at some time, along some dimension or in some context. In the case of “absolute nothing”, there is no location, there is no time, there is no ‘stuff’. It can occupy no component of any reality, real or imaginary. As soon as it does, it becomes something.
You keep trying to point me to a coherent concept of an existent nothing, but the problem is, you don’t seem to be pointing anywhere.
Sorry, but this is just word games. I don’t see what it adds to the debate. It’s a property of the English language that “nothing” is treated as a noun, just like cheese. So what? Not all nouns fall into the same conceptual category.
If you want to know what people mean by the hypothetical “nothing exists”, I have already told you. It means “everything that exists hypothetically does not exist”. What do you think is inherently self-contradictory about that hypothetical, phrased that way?
You can deliberately paraphrase something into its least comprehensible (to you) form, and then claim it is meaningless. At least make a good faith attempt to understand the intended meaning.
Please don’t assume I’m being dishonest or stubborn by refusing to agree with you. I will extend you the same courtesy and assume one of us is simply mistaken.
The way you phrase the hypothetical is not problematic as far as I can see. I take it mean that there may be a hypothetical state in which everything that currently exists does not exist.
It does not however, mean the same thing as “everything that could hypothetically exist does not exist.”
This is what I mean by “absolute nothing” and no, I don’t think that’s possible. I don’t even know what it really means to say that it might be possible. There is simply nothing there to be possible. It’s this that seems like the word game to me.
“not being could be” “being could have not been”
If you find some meaning in that, you’re welcome to it.
I don’t see the difference between these two hypothetical states. There is no need hypothesize that hypothetical things don’t exist. They already don’t exist.
I take them to mean the following:
A) It may be possible to conceive of a state in which none of the things which currently exist, exist.
B) It’s may be possible to conceive of a state in which there is a complete absence of things.
Does that clear up what I meant?
Exactly the point. No cosmos at all.
“Nothing” is a perfectly valid option.
You won’t win by using linguistic arguments. “How can it be ‘an option?’” That’s just playing “existence of God” games with words. There is no reason that “something” had to exist; it is wholly possible that “nothing at all whatever” was an alternative.
There are no winners here. My original comment was that you hadn’t justified your assertion. Your response is to reassert it.
I think that’s as good a point as any to declare that for me, this conversation is over.
This is all just word games. Just because our words aren’t adequate to describe an idea does not make the idea invalid.
I disagree with both sentences. 
I think calling existence a property is problematic, and leads to the kind of philosophical tricks where we define things into existence by saying they’re perfect.
It doesn’t really fit as an intrinsic property because there’s nothing in the definition of a concept that says whether it exists or not – e.g. does “Solid gold planet” have the existence attribute? We don’t know.
Even as an extrinsic property we still have problems because in our universe things don’t just appear and disappear; we have to arbitrarily say when some arrangement constitutes the existence of some new thing.
Better not to call it a property in my opinion.
“Nothing” of course has properties as a concept.
I think the confusion is possibly you’re taking “nothing” to mean NOT-(any noun, concept or attribute). I would agree with you that this kind of nothing makes no sense (unfortunately it makes so little sense that the sentence “nothing cannot exist” in turn is meaningless, because the thing we’re saying doesn’t exist is ill-defined).
But “nothing” really just means NOT-(any noun). It can have properties including a definition. So none of this applies.
Well, too bad, because all you’ve done is make your own assertions, without any comparable support…and you’re the one who made the positive claim. You said that reality had to exist, and that nothingness could not. You don’t have any support for that.
Taking your ball and going home is one way to lose a debate, but actively supporting your viewpoint is kind of better.
Why is “nothing” possible? Look at all the nothings that currently exist. The fourth spatial dimension. Even prime numbers larger than two. The observed cosmos before the Big Bang. Information that has been destroyed.
These are things that do not exist. The labels for them – “X is an even prime number greater than two” – exist, but the objects do not.
How about this: a cosmos, much like ours, exists, but atoms are spread out to only one every cubic parsec. Chemistry, life, existence, all are possible…but don’t exist. It’s an “empty” universe in the way that Cal Capone’s secret vault was empty. What possible philosophical argument could anyone make to claim that such a cosmos is “not possible?”
Better even is to just concede the point, that way the debate would have made some progress, and can move on to other points and conclude with a general agreement.
I’m a dreamer…
If failing to understand a relatively simple (though admittedly counter-intuitive) truth until the person explaining it gets bored of talking to you, is ‘winning’ in your eyes, then congratulations on your victory.
The OP began with a questioning tone.
But now it seems not only are you sure that you’ve solved arguably the most fundamental philosophical question of all, but it was relatively simple. And if people continue to disagree, and try to point out faults in your logic and/or premises that are actually disputed…well I guess they’re just dumb.
I don’t mean to call anyone stupid. That’s obviously not the case. I just thought it was outrageous that you and Trinopus immediately declared yourselves victorious when I suggested that the conversation was going nowhere and I didn’t want to continue. Am I supposed to keep debating an issue which I consider settled until either you accept my view or I die of old age? At some point, I have to move on.
Both of you have repeatedly misrepresented my views, accused me of saying things I have not said, and which are obviously false, ignored my criticisms of your own points and at one point accused me of not believing my own claims. Therefore, you either do not understand what I am saying, or you are being deliberately dishonest. You can both pat each other on the back, and tell one another that I fled in terror from your logic-bombs, but that is a fantasy.
I find this whole discussion increasingly unpleasant, and I wish to terminate it for that reason and that reason alone. Please feel free to continue in my absence.