That's a different question; I was establishing the plausible existence of the material, not establishing the implausibility of Cartesian dualism.
I don't think you can wave away epistemology so easily. The problem is that while it's all well and good to talk about ontology--fundamentally I agree that we are--we nonetheless are in the position of figuring out which ontologies seem sufficiently consistent with our experience and which don't.
This is why epistemological solipsism is something worth talking about. As a practical matter, if you can't reasonably come to know anything outside the contents of your own mind, whether or not you postulate that there is anything is largely irrelevant, save that the very thing that makes you an epistemological solipsist--doubt--actually prevents you from becoming a metaphysical solipsists. Self-doubt (epistemological nihilism) as well is that which Descartes battled with his famous phrase Cogito ergo sum. So, fine, anyone who can think "I think, therefore I am," we can say has awareness of their own existence. But the question is how to get anywhere else, including to know anything about the nature of their own existence.
You rightly point out that any sort of intuitive epistemology provides oodles of evidence that there is something external. But the same intuitive epistemology leads most naturally to Cartesian dualism, because there seems to be a stark contrast between other experiencers (e.g. you, to me) and many non-experiencers (e.g. a rock).
As an idealist you thus face an immense challenge: the very stratagem that you use to escape solipsism also seems to indicate that dualism is true. Now, we already granted (given experience with our own confusion wherein things that seem one way at some times seem another at other times) that appearances can be deceiving. Just because dualism superficially appears true doesn't mean that it is true.
But what's been happening over the past four centuries is that materialism has been racking up win after win after win, demonstrating that processes once thought to not be material in fact are (e.g. life vs. unlife) and eroding the purview of the mental realm to the point where one wonders why we bother to retain the distinction as an ontological matter instead of just saying, "Yeah, apparently experience is just another type of dynamic process happening within the physical world."
Any leap of faith, any miracle you invoke to undergird idealism, I insist that I be allowed to equal extent to try to undergird materialism instead, and if you forbid both of us from such leaps, then I think you will find yourself stuck in (epistemological) solipsism.
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"Thinking that pure quantities can give rise to their polar opposite in qualitative experience is magical thinking, there's no other way to say it."
What, and thinking that there's a universal mind isn't even more magical thinking?
You keep making this charge and you never back it up with anything at all. You just declare, over and over, that it's magical and give expressions of incredulity when someone deigns to consider an alternative.
This is exceedingly unpersuasive. I already have given explanations that seem fully nonmagical to me. To me, it seems as though I've folded an origami crane and you're saying, "but that isn't from a single sheet of paper with no cuts, it's impossible, that's magical thinking". And yet here I have the crane and it sure seems to be paper, and no cuts are in evidence, and I can show you the folds.
"What happens is you start folding paper and then there is a miracle and you get a crane--it's not a result of the folding," you seem to say.
And I say: *facepalm*.
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"You're breathing every moment of every day, yes? [..] If you weren't, on some level, aware of this then it stands to reason that you'd cease doing it."
This is controlled, non-consciously, by the action of various neurons (and muscles, of course), and is quite well understood: https://en.wikipedia.org/wiki/Control_of_ventilation#Control_of_respiratory_rhythm
We quite explicitly don't need to be aware of it any more than we need to be aware of any process that runs itself.
Now, you can go the panpsychic route and say, "Well, it has its own awareness." But you certainly can't go the route of saying that we'd cease doing it without being "aware of this on some level". No, you really, really don't.
It does not stand to reason at all that because you can be aware of something and awareness can supervene upon how something happens that you must be aware of it for anything to happen at all. That is of course one possibility, but not the only one.
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"If awareness, properly understood, were ever impedied in any way then you wouldn't even know that the thing in itself had occurred at all. Explain how you get around that."
I think you need to explain what "properly understood" awareness is.
Otherwise this is trivially and blatantly incorrect.
For instance, if awareness is a graded capacity, then of course you could impede it--just not fully--and still know that a thing occurred. Maybe not as clearly, maybe missing some detail, but you'd know it happened.
Furthermore, if actions leave traces in the real world (including our own bodies), then even if we're completely unaware of something, one can examine the traces and then know indirectly that it had occurred.
This is so trivially easy to get around that I conclude that you must mean something else.
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"Let's go w/ a particularly traumatic example of cardiac arrest in which the heart stops beating, blood flow is cut off from the brain and all significant brain activity shuts down. Surely if there were a conclusive example of the physical brain producing consciousness, it would be here, yes? Shut down the brain and it should be absolutely impossible for any experience whatsoever to occur. Clean correlation, right?"
Yes, if the brain is actually shut down.
But you linked to a paper that assumes it and doesn't document it. That's pretty useless. How do you know that there isn't just more activity than expected under low-oxygen conditions?
The brain already engages in plenty of glycolysis. It has an energy source available in addition to oxidative phosphorylation. But it's less efficient and makes harder-to-deal-with byproducts.
There's plenty of possibility that there's still neuronal activity, and given the diversity found across people, you can't check a few people in one condition and assume it's always true for everyone and that therefore uncommon reports of something else mustn't have anything to do with it.
There's also a disturbing degree to which we've previously made bad assumptions in this regard, including "locked-in syndrome" where people are conscious but unable to respond, but for which we can (sometimes) create computer interfaces using EEG to read out their responses by monitoring changes in brain activity (which they are still able to control).
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"Why do I believe that things cannot possibly be that way because of their structure? What you even trying to ask?"
Aside from bare vehement assertion over and over and over again, what reason do you have to think it could not possibly be this way?
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"Your assertion was that evolution could be primed to value truth over survival given certain circumstances. Your rationale for this is...?"
No, my assertion was that Hoffman asserted that evolution would value survival over truth in certain conditions and those conditions don't always apply.
My claim is that in those situations, a good approximation to truth is the only survival-enhancing function. And this is precisely the case where the relationship between survival and truth varies too fast for evolution to adapt to the answer.
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"Why should some group of neurons convey the experience of the color red as opposed to the color green? They're all just neurons at the end of the day."
Yes, and letters are all just letters at the end of the day so what is the difference between the words "egret" and "greet"?
If you can answer that question, then you have to ask a more sophisticated question about what differentiates the "experience of red" neurons from the "experience of green" neurons. (Note that neurons are interconnected in far more complex ways than letters, also.)