But this naive picture wouldn't be correct as applied the the photon's relation to the electromagnetic field either!

Nobody (as far as I know) has ever proposed a naive picture whereby a photon travels through the electromagnetic field. That would be a complete misunderstanding of electromagnetic theory. The naive picture, if there is one, is that the photon travelling through a region of spacetime is what constitutes the electromagnetic field in that region of spacetime. It is just here that the graviton as a particle model breaks down. The description of a graviton as a quantized part of spacetime (which I think is what you are getting at, but correct me if I'm wrong) makes perfect sense, at least if one allows that the structure of spacetime is discrete and not continuous, but the relation of the graviton to spacetime then becomes one of part to whole and the graviton is no longer a particle at all - it becomes a discretely identifiable element of the medium through which energy-bearing particles such as photons and gluons etc transfer their energy. However, one fairly standard picture of a graviton is to model it precisely along the lines of a photon insofar as it is also something that transfers energy from one part of space time to another, and that is the picture which I believe is fundamentally confused about what gravity actually is.

This would be a good starting point - https://www.nature.com/news/physics-quantum-quest-1.13711

Perhaps my reading is even more superficial than the article, but it seems to me that the new probabilistic approach being sketched in the article is just a vamped-up epistemology of QM, not a radically new metaphysical interpretation. It may end up predicting new experimental results and new ways of applying QM, but the metaphysics seems largely untouched.

As for attempting to link QM and GR, for me that has always been based on a fundamental error in understanding GR. Gravity is a force under Newtonian mechanics. Under GR gravity is not a force at all, it is the manifestation of the structure of spacetime, and is thus not something that can be transmitted from one body to another via particles like gravitons.

@Eros1982Maybe I could have been a little clearer about why the formula AxEy((Rxy & -Ryx) & -(Rxx <-> Ryy)) is not true in the domain you give.
The interpretation contains a and b, with extension for R <a,b> and <a,a>.
Within the context of that interpretation, elimination of universal quantification allows us to infer
Ey((Rby & -Ryb) & -(Rbb <->Ryy))
The extension for R you give does not allow for (Rby & -Ryb) to be true no matter whether you replace y by a or by b, but those are the only two possible replacements in your interpretation. This means that in the interpretation you give, the universal claim made by the formula just is not true. Obviously, adding <b,a> and <b,b> to the extension of R is not going to help. So, there is the need to have more than two objects in the domain in order to allow for the necessary flexibility in the extension of R, in order that we can get the universal claim to be true for all possible substitution instances of x. If you reiterate this kind of reasoning my guess is you will end up showing that AxEy((Rxy & -Ryx) & -(Rxx <-> Ryy)) is true for a domain with four objects (a,b,c,d) and some appropriately chosen extension for R. Hope that helps.

That's a tough one. I guess you have to show that the negation of the formula can be true under some interpretation, which seems to be what you are getting at. What you have to show is that in some interpretation the following is true:
AxEy((Rxy & -Ryx) & -(Rxx <-> Ryy))
An interpretation with two objects a,b and the extension for R <a,b> , <a,a> would not do that (you can make all the substitutions to see for yourself that the above formula never turns out to be true). You'd then have to play around with a,b,c and the consequent possibilities for Ext R to see if you could get any further. I suppose if Forbes/Mendelson is correct you need at least four objects in the domain and an extension for R that is suitably restricted. Note that for -(Rxx <-> Ryy) to be true under an interpretation you need the truth values of Rxx and Ryy to be opposites of each other.
To be honest, I doubt you'll have anything as challenging as this to deal with in your exam.

So @MetaphysicsNow's point is more or less the freedom of will issue that I raised a few days ago :

There are issues about freedom of will involved here aren't there?

Sure, 4 might need some more filling out, but the filling out is to be neurophysiological in nature. There is perhaps an epistemological point that we don't know enough about neurophysiolgy currently to explain the behaviour this way, but the point is a metaphysical one that - whether we know it or not - there is a sufficient neurophysiological reason (in the sense of fully sufficient neurophysiological cause) for the repetitive behaviour.

X is not saying 'that the entire element of choice is nullified by physiological abnormality'.

I think Metaphysics now is trying to suggest that even if X is not explicitly saying this, what X is saying does entail this. That to me is the import of the first premise of the sketch argument given. Not sure how the implication holds, but then it's not my argument. My guess is that there's somekind of "being consistent with explanations of actions" principle lying behind it, but maybe not.

Denmark is indeed often pointed to as a model working state. I'm interested though: I've been reading recently that there may be structural problems with the model that are being exposed in the current context (e.g. https://www.humanityinaction.org/knowledgebase/59-the-danish-illusion-the-gap-between-principle-and-practice-in-the-danish-welfare-system ). As you are someone who lives in Denmark, what is your first hand experience of this?

↪NKBJ
Have you read George Orwell's Road to Wigan Pier or Down and Out in Paris and London? Both are about Orwell's experience of British and French poverty in the 1930s. Excellent.

Orwell was an exceptional writer and human being. Another work in the same spirit by another writer (although this time fictional) is The Ragged Trousered Philanthropists by Robert Tressell.

True, but capitalist systems regularly produce a surplus from which the poorest can be taken care of, if the society sees fit to provide such care.

I think the issue is that whilst society is mired in capitalism, seeing fit to disperse the surplus freely is not a coherent option. Under capitalism the surplus is the source of profit. Disperse the surplus freely: no profit. No profit: no capitalism.

Not a coincidence!

So when we will get this promised proof of God's existence then?

I too would like to live in such a world, and contrary to @Bitter Crank's comment, there are plenty of resources around to do this, although many of us in the so-called "developed" world will have to drop our expectations about what counts as a "nice" house. However, you are right that it cannot be done under capitalism because, as Bitter Cranck points out, the ethos of capitalism is not to produce necessities in order to meet basic needs, but to produce necessities in order to create profit: human beings are treated as means to ends, not ends in themselves. The kind of world both of us would like to live in is essentially a socialist one and, as Marx pointed out, a socialist economy can only thrive once technological progress has reached the point where basic necessities for all can be provided. Technology is sufficiently advanced now to do precisely that, the question is how to we transition from capitalism to socialism.

The basic necessities of life need to be produced. The current mode of production is capitalistic, a system which requires that people pay cash for those products. I certainly don't think a capitalist economy could function by giving away the necessities and only selling the "luxury" goods - which seems to be what you are proposing. The production and sale of necessities is the foundation of the capitalist system, the production and sale of luxury goods is parasitic upon it. Take away that foundation and the whole edifice collapses.
Having said that, no economic system is going to just give away the necessities of life - under socialism, everyone might receive the basic necessities without handing over cash, but (most) people will still have to pay for them by engaging in socially necessary labour to produce them.

There are issues about freedom of will involved here aren't there? X's position seems to be that his OCD rituals are out of his control because caused by some physiological condition. But if OCD rituals are caused by abnormal physiological conditions, then so presumably X's "normal" behaviour patterns are caused by "normal" physiological conditions, and would thus equally be out of his control. Is X prepared to accept the consequence that absolutely nothing he does is within his control? By trying to avoid responsibility for his OCD, he seems to be commited to having no responsibility at all for anything he does, which means - amongst other things - he can take no pride in any of his acheivements.

Quantum mechanics is at best irrelevant to the idealism v materialism debate, and at worse just invites obscurantism and confusion.

Take a look at the Kastrup thread - plenty of confusion and some obscurantism, doesn't help that QM purloined the term "observer".
Anyway, I'm interested in what you say about proving idealism by analysing perception - have you read John Foster? He attempts to argue for idealism entirely indepentently of the usual kind of arguments from illusion and hallucination.
By the way, any relation between you and MetaphyicsNow.com, or is that just coincidence ?

I have the horrible feeling that @numberjohnny5 is going to come right back at you and say relations are just mental and so material things always in flux , T1, T2...etc etc etc. Basically, numberjohnny5 is regurgitating the Heraclitan idea that everything, everywhere at all times is in flux. What numberjohnny5 needs to do is read Plato's Theatetus for the definitive refutation of that idea. The basic idea of Plato's (and I think @Metaphysician Undercover is getting at precisely the same point) is that the notion of flux only makes sense in the context where there is a background of stability (and one can turn the table also and say even the notion of stability requires that there is some kind of flux). So insisting that everything is everywhere and always just a seething soup of flux is, no matter how much technical jargon you dress it up in, meaningless drivel. Like @Wayfarer, I think this thread has run its course, although I suspect that the serious issues raised during the exchanges will rear their heads in other discussions.

Because to account for the fact that there is (presumably) more than one thing that is true, you'd have to have different particular things interacting inone and the same (truth-creating) way.

Thanks for the précis! OK, his answer to the question is full of references to non-neurological concepts (power/simplicity etc) - so I guess the question now is why even bother with all the neurological underpinnings if the ultimate explanation one is going to give for sociological phenomena is going to be sociological and not neurological in nature. Anyway, thanks for starting the thread, I learnt something through it.

I don't know about ProcrastinationTommorow, but for me your reply misses the point.

"Truth" is a property of propositions/claims — numberjohnny5

And then you ramble on about propositions being ultimately brain states or whatever. Fine, ProcrastinationTommorow seems to be ceding the point that it might make sense to equate propositions with brain states, but what he is challenging you with is to come up with an account of truth that doesn't surreptitiously or explicitly imply the existence of non-particular, not-material things. Even your definition of objective relations just introduces another term that looks like a non-particular : i.e. ways of interaction.

Why does the mind, seat of rationality, like an unsolvable riddle? — TheMadFool

I'm not sure the mind likes anything, but insofar as you mean "how do paradoxes arise"? perhaps Kant's suggestion is worth thinking about: that it is a result of us taking principles of theoretical reason that apply only to actual and possible experience, and trying to apply them beyond all possible experience.

''This sentence is false''.

The accepted solution is to call it nonsense - that it's not a logical proposition. Isn't that convenient? I could do that to all paradoxes too but surely that would be avoiding the problem rather than providing a solution. — TheMadFool

There are many different types of solution to the liar paradox, I don't think any one of them qualifies as "the" accepted one. The Tarski-style response, that truth cannot be part of the content expressed by a sentence in any given language, would make the sentence nonsensical, I agree, but there are other responses, including some that involve rewriting classical laws of logic - such as getting rid of the law of excluded middle - which would leave the sentence expressing something meaningful.

Too many books to read, too little time in which to read them. Ghilcrist is a long way down on the list - I'm looking for a précis :wink:

I think you pinpointed the real problem with this kind of discussion in your first post above: human beings (and perhaps other animals) think and feel, not their physiological parts. Of course, playing around with any of the physiological parts of a human being might affect how they think or feel, but we all already knew that : if you stub your toe, you feel pain, but it's not your toe that feels pain. Same principle: if you stimulate the visual cortex you can improve spatial recognition (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4961578/) but it's people that see things, not visual cortexes. Same principle: if you add an artificial heart, the patient's reactions to people might change (it's pretty major surgery after all) but it's neither his real nor his articifial heart that reacts to people. In Ryle's terminology, a fundamental category error is being made even by posing the question: Can the heart think?

Moliere is (par for the course :wink: ) right, I think. Provided that one views any purported causal correlations between mind/brain as causal correlations between observed (and possibly, obervable) events, and not causal correlations between soft chunks of matter and intangible vapours of mind, the ontological issue between realism and idealism is untouched by the neurological research of scientists like Ghilcrist (of course, bearing in mind the Kastrup thread, I have to insist here that "observe" is being used in its usual and strictly phenomenal sense, and not in any sense the word might have as it functions in the spiel of realist QM theorists). This is presumably to take the "instrumentalist" view of neurology that ProcrastinationTomorrow recommends. The idealsim/realism issue would be about whether one can be instrumentalist about neurology without also being a realist about the brain - that is where the jury is really out.
I haven't read the Ghilcrist article that sparked this discussion, so cannot comment on his analysis. However, if he is suggesting that we can analyse societal development in terms of the domination of the right-hemisphere by the left-hemisphere of the brain, then the question would arise as to why the left-hemisphere became dominant, and in responding to that question, perhaps the ontological issues become more signficant. To anyone who has read the interview, or any of the works of Ghilcrist, what response does he have to that question?

Frege certainly appears to have been a realist about all kinds of mathematical objects: numbers, functions, sets.... What I'm not clear about from the Burge essay is that he appears early on to make some distinction (on Frege's behalf) between thought contents, on the one hand, and mathematical objects on the other: what's that distinction supposed to be? Obviously not every thought we have is going to be about mathematical objects, but when we do think about maths, for instance, when we consider whether some function is a derivate of another function, does the distinction between thought contents and mathematical objects dissolve?

Thanks Wayfarer - I'll take a look at that paper: I've heard of Tyler Burge in other contexts (externalism in the philosophy of mind) but have not read any of his papers. However, I think even the examples you gave might run up against the principle of sufficient reason (PSR) line of thought. Let's suppose our two distinct realms are the abstract and the particular. If we apply the PSR from the point of view of the abstract realm, no need for particulars, so no particulars. If we apply the PSR from the point of view of the particulars realm, no need for abstract objects, so no abstract objects. So the pressure remains to get rid of one or both realms. I think perhaps for me the issue for dualisms of all kinds is to find some substantial notion of a connection between the two posited realms which on the one hand satisfies the PSR, showing why there must be not only one, but two, whilst at the same time not collapsing the fact that they are genuinely distinct and not really just one thing disguised as two.

↪Metaphysician Undercover

I don't see how "self-containment" is even relevant. I would think that if the descriptive terms used to describe the properties or attributes of the members of one realm are distinct from, and not reducible to the descriptive terms of the other, then the two are distinct.

Doesn't that miss jkg20's point?

Yes, I think so - in any case I'm still waiting for a definition of distinctness of realms in terms other than self-containment. However, your point about the dualism issue possibly making sense when shifted to talk of properties rather than realms is food for thought - I'll have to think about that - but I initially I think my general point could be recast.

Assume two distinct realms, be it properties or substances or whatever: what makes them distinct? You cannot just help yourself to the fact that they are distinct (well, you could, but then you wouldn't be doing metaphysics). So, you try to move forward by providing necessary and sufficient conditions for something to be in one of the realms or the other. But, if they are not strictly logically contradictory conditions, how do you rule out the possibility of one thing meeting the necessary and sufficient conditions for being in both realms, and thus destroying their distinctness? Because, one wants to insist, precisely because the realms are distinct - but then we are back to where we began - we're just asserting and not establishing distinctness. So, we shift the abstract definition of distinctness a little more and we add the condition that the realms are self-contained - but what does that add? What it adds, at least under one expansion of the idea, is that the items in distinct realms could exist in the absence of all items in any other possible realm, which clearly excludes the idea of one thing being in two actual realms, because one thing cannot exist in its own absence. And now here comes the principle of sufficient reason (which, incidently, is not uniquely concerned with causation). The principle of sufficient reason simply states that only that exists for which there is a reason why it exists (the reason may be a cause, but it may be something other than a cause). But now suppose we adopt the perspective of one of these mooted self-contained realms. All things in it exist independently of any other realm. So, what would motivate, from the perspective of this realm, the idea that there might even be another realm at all? Since this realm is self-contained, there is no causal dependence of this realm on any external realm. Also, if we suggest that a second realm might be the causal offshoot of this realm, the principle of sufficient reason reapplies - why would there be such an offshoot if nothing within this realm requires it? We might try to look for non-causal connections between realms that could answer the demands of the principle of sufficient reason, but even though not all reasons are causes, I'm not sure whether a non-causal reason would fare any better at giving (from the perspective of one realm) a sufficient grounds for the existence of another realm. Having said that, it's entirely possible that there are options that have not crossed my mind.
So, the next move is to say that the principle of sufficient reason should not be applied from the perspective of any given realm, and so has no bite in this line of thought. But is it possible to apply that principle without applying it from some realm or another? This is a genuine question, not a rhetorical one, by the way.
Alternatively, we ditch the principle of sufficient reason entirely - but, since that is (arguably) the principle that motivates all science and philosophy (if you make a difference between the two) that seems a little drastic and possibly self-stultifying.
So, I remain currently unconvinced that dualism is a genuine alternative to monism.

OK, but by introducing the notion of appearances into the definition of metaphysical realms, the suggestion appears to be that what we can know puts a limit on what there is. Is that what you intend, or have I misunderstood the suggestion?

Yes I do mean Identity Elimination, and its precise use for you will depend on exactly how the IE rule is defined by Forbes. However, as I was taught, the identity elimination rule basically just tell you that from a given identity statement
a=b
say
you can change any occurrence of 'a' in any other statement in which 'a' occurse with an occurence of 'b', and it would also allow any occurence of 'b' in any other statement to be replaced with an occurence of 'a'. So, in my argument I use the identity a=b to replace the 'a' in a=c with 'b'

If the IE rule you have been given requires that the subsitution made be sensitive to the exact order of the terms in the identity statement, then you may have to go through some additional steps of swapping the terms around, but the rules as I remember being taught them did not require this.

Don't get me wrong, I'm neither a monist nor a dualist, I'm just curious. So how does one define distinctness of metaphysical realms if not in terms of self-containment of that realm? Perhaps I'm overlooking something in your post, but I don't see a definition.

Conditional elimination rule is basically just another name for modus ponens, so yes, if you are going to use it, you will need to either assume the truth of your antecedent, or to have derived that antecedent from other premises/assumptions you have already made in your argument. The thing to remember is that it is not an assumption discharging rule of inference: any assumptions you still have in play up to the point you use modus ponens/conditional elimination, remain in play after you have used that rule. Although the "numbers on the left" are apparently not obligatory for your exam, they can be very useful for keeping track of what you are still assuming in your argument (in fact, that is really what they are there for) so whilst you are revising, it might be worthwhile trying to use them, even if in the exam you can take a shortcut and forget about them.

Let Realm A be the Conscious Realm where all our Conscious experiences happen. We can put all Conscious experience in it's own Realm because we don't know what Conscious experience is yet. For example Science does not say anything about what the experience of Red is. At this point it just Is. So it makes sense to put it into a separate Realm.

I suppose I'm trying to approach the issue purely metaphysically, not epistemologically (and therein may lie my confusion). That we might not know enough about which realm a given thing should be assigned to seems to me to be a different issue from pursuing the very idea of two metaphysically distinct realms in the first place. Whilst am happy to assume that what there is might have an effect on what we can know, I'm less inclined to believe that what we can know might have an effect on what there is. But maybe I'm making the kind of mistake here that Kant thought he'd analysed and treated in his Critique of Pure Reason.

To separate two things as "distinct" things, does not require that those things do not interact with each other. You and I are distinct things yet we are interacting here. So I think you are placing unnecessary restrictions on your definition of "genuinely" distinct. If that is what is required to be genuinely distinct, then absolutely nothing could be genuinely distinct from anything else, because it would have to be self-caused. So that definition of "distinct" is unreal and unacceptable. We ought to allow that distinct things may interact with each other.

The metaphysical issue concerns distinct realms, not distinct things within realms. You and I are distinct things, perhaps, but we are not in distinct realms. Metaphysical dualism requires two distinct realms, and the only way I can see of fleshing out the notion of separate realms is in terms of self-containment. That things within the same realm might interact with each other is unproblematic (or at least less problematic) but that things might interact across realms is precisely the issue I'm trying to dive into at an abstract level. Descartes, for instance, gets into trouble at this point - he believes he has established the existence of two distinct realms (he calls them "substances"), the mental and the physical, but if they are genuinely distinct, how can they possibly interact? Of course, Descartes just assumed that they did interact, rather than pursuing the idea that the very notion of two distinct metaphysical realms interacting does not make sense in the first place (which I think is one of the issues Spinoza has with Descartes).

You're right, I could be clearer in expressing my concerns. I think the issue I'm worried about has the principle of sufficient reason at its core. I'll have another go at explaining my confusion more clearly.

Let's suppose you believe that reality consists of two realms, we can neutrally call them realm A and realm B. If they are genuinely two distinct realms, then they are self-contained insofar as all the elements in one realm can be accounted for in terms only involving other elements of that same realm. This is real dualism about reality.

However, realm A becomes epiphenomenal with regard to realm B and vice-versa. But the principle of sufficient reason would then require us, from the perspect of realm B, to reject the existence of realm A, since realms that just "tag along for the ride" have no sufficient reason for existing. Similarly, the principle of sufficient reason would require us to reject the existence of realm B when considering things from realm A. We might want to try to take a third way, but we are assuming that reality just consists of two realms, so there is no third realm we can go to for adjudication.

So, we then suppose that realm A and realm B are not separate realms. We might think that everything we previously presumed to be in realm A can be accounted for by things in realm B, or vice-versa, but we thus eliminate one of the two realms we presumed to exist in the first place. We might want to try an approach that said that there is at least one thing in what we used to call realm A that cannot be accounted for by things in realm B, but then we are just keeping realm A as a self-contained realm, but with a shrunken domain, and once again from the perspective of the enlarged realm B, it becomes epiphenomenal and so its raison d'être is removed. And similarly, from the perspecive of this reduced realm A, realm B is redundant.

So, the principle of sufficient reason pushes us towards monism.

There might be some conceptual confusion going on in the above, maybe in my assumption that if reality consists of two realms, then the principle of sufficient reason is applicable in both realms individually. But if the alternative is to say that the principle of sufficient reason has to be applied from neither realm A nor realm B, then we seem to have two choices. First, we could suppose that the principle is to be applied from a perspective in reality. But then we have have to introduce a third realm to reality, and the same line of thought as applied above to realm A and realm B would reapply to realm A + realm B + realm C, and the pressure for monism remains. Alternatively, we could try the line that the principle of sufficient reason is not to be applied from any perspective in reality at all, but that requires that we be able to make a distinction between not applying a principle from within reality, on the one hand, and not really applying the principle at all, on the other, but that smells like a distinction without a difference.

Enjoyed this post, and particularly

The second component is ego, which was comically avoided in this article. I’ve spent a long term around other academics and many of them are ego-driven jerks

I ventured into academia a little later than most, and generally got the feeling that many (though not all) of the faculty members were very clever children whose emotional development was arrested back in the school playground.
Anyway, sometimes I think the main problem in academia these days is that the whole university system remains mired in a spirit of feudalism, whilst trying to negotiate a world that has evolved economically into capitalism (don't get me wrong, I'm no apologist for capitalism, but nor for feudalism either). Maybe we need to move away from the idea that we do all our studying up to the age of 21 (or for some of us a little later) and then ditch it and get on with earning money, and move towards a world in which work and education really are both life long.

Hi. Discharging assumptions basically means that you are no longer relying on the "fact" that they are true. Let's try putting your proof into "natural language". You have
2) If John is Jane, then John is Janice. (by Universal elimination)
3) John is Jane. (Assumption)
Given assumption (3) is true, then you infer:
4) John is Janice
from the conditional elimination rule applied to the conditional (2).
This is fine. However, the conditional elimination rule does not allow you to discharge assumptions. In using that rule you are in effect relying on the truth of the antecedent (in this case that John is Jane). So, the statement (4) that John is Janice is relying on your assumption that John is Jane.

There are three principle ways of discharging assumptions: conditional introduction, negation and existential elimination. I won't deal with the latter, as it is one of the more complicated inference rules, and to get an idea of what's going on with assumption discharge, we don't need to look into its deatils. So, for negation, if you introduce an assumption in your argument:
John is Jane
and then later on in the argument , one way or another - it doesn't matter how as long as you follow the rules - you arrive at the statement
It is not the case that John is Jane (or more colloquially, John is not Jane)
you have gotten rid of your initial assumption simply by "denying it".

A more subtle way of discharging an assumption is by introducing it as the antecedent of a conditional. The very basic way of doing this would be the following:
1) John is Jane Assumption
2) If John is Jane, then John is Jane ->I
Of course, you are not saying an awful lot in 2) - it's basically just an empty tautology - but never the less, you no longer are relying on the fact that John is Jane in order for (2) to be true.

In my version of the argument above, I use the conditional introduction rule twice in order to discharge assumptions. Picking on this threesome of John, Jane and Janice, I have
John is Jane Assumption
John is Janice Assumption
If John is Jane then John is Janice ->I
In making that move I discharge my assumption that John is Jane and leave everything about my argument hanging on whether or not John is Janice.

I hope that helps.

As an aside, one good general technique when what you are aiming to prove is a conditional statement, you should be looking to make the antecedent of the conditional an assumption, and the negation of the consequent your second assumption, and then look to draw a contradiction. But in this case that doesn't seem necessary.

The problem as I see it with your answer is that you have the undischared assumption at line (3) still lingering around by the time you get to line 7. I think one way of doing might be as follows
1 (1) a=b Assumption
2 (2) a=c Assumption
1,2 (3) b=c 1,2 IE
2 (4) (a=b -> a=c) 1,2 ->I
(5) (a=b -> a=c) -> b=c 4,3 ->I
(6) Ax(x=b -> x=c)-> b=c 5, AI

I discharge all my assumptions by line (5) using conditional introduction, and since (5) depends on no undischared assumptions or any premises, I can use universal introduction to replace all occurrences of a.

Thanks ArguingWArisotleTiff - I like logic, so it was a pleasure to try to help!

If by that you mean "we as conscious beings are deluded about the true nature of reality" then that is certainly better than "consciousness is an illusion". At least at a superficial level it appears to make sense as a proposition, the truth or falsity of which can be investigated. However, it needs to be pointed out that even making sense of the notion that we are deluded requires a background assumption that at least sometimes we are not deluded. So "we as conscious beings are deluded about the true nature of reality" cannot sensibly be taken to mean "we as conscious beings are permenantly deluded about the true nature of reality".

I'm still not so sure why you are apparently so closed-minded about the role of conscious observers in QM. Adrian Kent - by all accounts an exceptional QM theorist and practician - seems to be open to the possibility that there is fruitful terrain to be investigated. https://arxiv.org/pdf/1608.04804.pdf There are certain realist assumptions lying behind much of what he says, with which an idealist would take issue, but nevertheless here is a serious scientist taking seriously the idea that conscious observation (whatever that might be) might have experimentally observable effects on quantum systems. Just closing off any such line of investigation seems unscientific.