Proof that everything that can possibly exist does exist

This is an adaptation of the sixth bullet point under https://myriachromat.wordpress.com/2020/06/18/notes-on-existence-and-the-multiverse/.

1. Whether something exists or not is a function of the contents of its greater physical and metaphysical context and history.
   1. For example, if a tree exists, it’s because another tree, which is or was likely in the same vicinity, dropped a seed sometime in the past, that was sufficiently nurtured as to grow into that tree. If a house exists, it’s because of the confluence of the desires and actions of many people in the context of a culture and civilization.
   2. All of the above things are dependent on the principles of physics, which ultimately exist for metaphysical reasons: you can’t empirically measure why all the laws of physics are as they are. For anything you can empirically measure, you can always ask why nature rendered that particular measurement for you as opposed to some other measurement.
   3. We can conclude by extrapolation/induction that whether the universe itself exists or not depends on some greater metaphysical context.
   4. We can also conclude this from the reasoning that, if it weren’t for some particular metaphysical context to determine the specific nature and contents of the universe, there would be nothing to make it exist in the particular way it does/with the particular contents it does as opposed to in any other particular way. In other words, there’s nothing to select from all the conceivable possibilities.
2. Therefore, if there were the lack of any greater metaphysical context/history, either everything/every universe that can possibly exist would necessarily exist, or nothing would exist.
3. If there is an absence of a greater metaphysical context to the universe, then neither is there something to determine which is the case between whether all conceivable possibilities are manifest or nothing at all is anywhere.
4. The greater metaphysical context that determines that the universe exists, and which particular universe is the case, or alternatively, that all possible universes are manifest or nothing is, must itself have an even greater metaphysical context, or else there would be nothing to determine that that metaphysical context is the the way it is as opposed to any or all other possible ways.
5. If that greater metaphysical context doesn’t itself have an even greater metaphysical context, or if this isn’t the case on any level of consideration/regress, then, in turn, there’s nothing to determine that only that metaphysical context exists as opposed to any and all metaphysical contexts existing and thus giving rise to all conceivable possibilities, or any reason that metaphysical context is the way it is as opposed to any other way, or any reason it would even exist.
6. In the absence of a metaphysics to determine whether every possibility or no possibility is made manifest, either both possibilities come true (i.e., that every possibility is made manifest and nothing is made manifest), or neither possibility comes true (which would seem to to identical to nothing coming into existence, only on the next higher level of metaphysics/consideration).
7. In such a case, it is not determined whether the first of the two above possibilities comes true (i.e., that every possibility is made manifest and nothing is made manifest), or the second of the above possibilities comes true (i.e., that comes into existence, only on the next higher level of metaphysics/consideration).
8. This conundrum reaches backward into infinite regression; i.e., there would be the lack of a metaphysical context to determine if every possibility is manifest or nothing is manifest, and a lack of a metaphysical context to determine the nature of said metaphysical context, etc. ad infinitum.
9. So, there would ultimately be nothing, no first cause or ultimately overarching state, to determine whether all possibilities are manifest or nothing is; it’s both both both and neither to infinite regression.
10. It seems that, therefore, out of the infinite depths of metaphysical possibility, would spring both every conceivable possibility and nothing at all, where the “every possibility” is always one more level of consideration up from the “nothing” possibility. The metaphysical nature/foundation of what seems to exist would therefore be infinitely deep, as would the truth of whether it really exists or not, so it’s as if reality is a daydream within a daydream.
11. If that’s the case, you may ask, why is it that we observe the “something” possibility rather than the “nothing” possibility? The answer is the same reason you observe the North Star but not the space between here and the North Star. Both exist simultaneously—everything an nothing—but of course the only one of the two you can ever notice is the everything.
12. You may ask, why is it that we only observe a limited universe, instead of every conceivable possibility? The answer would be that every conceivable possibility includes those possibilities where perceivers can’t observe every possibility at once/from every vantage point. This universe, or biological life on Earth, is one of those possibilities.
13. To be fair, so far we haven’t actually proven the lack of a greater and greater metaphysical contexts that would necessarily give rise to both all and no possibilities. It could be that there is an infinite or unlimited regress of greater and greater metaphysical contexts/histories, and that at the top, it’s ultimately determined that only one or a few possible universes/things/experiences are made manifest. But then, that consideration contains a contradiction: if there is an infinite/unlimited regress of metaphysical contexts, then there is no absolute top. And if there is no absolute top, what is there possibly to ultimately determine which conceivable possibility is made manifest as the universe we observe? Thus, that idea seems impossible.

One possible argument against this relates to my careful choice of the word “consideration” in the above steps. The argument would be that this entire argument exists in our consideration only, and as such as purely epistemological as opposed to ontological/metaphysical. (And, you could say, the concept of possibility isn’t a metaphysical or ontological one, but epistemological: that, in reality, there was only ever one possibility, which was that which happens.) But that argument would rely on the assumption that you can’t conclude anything about metaphysics based on purely epistemological deduction. And as I mentioned in the essay linked to at the top of this essay, due to both the absolute primacy and non-empirical nature of both metaphysics and epistemology, at some point metaphysics and epistemology are inextricable from each other.

Note bene: This argument does not exactly stipulate an infinite regress of physical and metaphysical contexts, which would beg the question, since that would be claiming existence of something. Note the words “in the absence of” above…it’s about an infinite regress of a lack of outer contexts. (This is again why the argument is primarily an epistemological one.) What really matters is that there’s nothing determining that the outermost context that actually exists, exists. But not even that really matters, because the argument does not actually depend on anything already observably extant to work; it just uses what we do know exists as a sort of trampoline or starting point/reference point for reasoning.