I'm not sure about Ryle's assessment of the University. Take the emergent complex behavior of ant colony and apply that to human social structures. There is something more than the organization structure of the colony or the university.

I would say that your existentialism is of a conservative religious variety , as opposed to the later Wittgenstein’s or Sartre’s existentialism. — Joshs

Fair comment, with the caveat that I don't self-identify as Christian (although sympathetic towards Christian Platonism). But I share (often unwillingly) with many of the perennialists a deep suspicion of modernity. (I think there's a streak of that in Heidegger isn't there?)

Yes, what you call the "genuine conundrum" is metaphysical, not physics. — Banno

So out-of-bounds according to you. But the reality is, metaphysics has a way of forcing itself on us. Heisenberg is quite an astute philosopher concerning the metaphysics of physics, a lifelong student of Plato.

:chin:

The Reductionist ignores the context - the purpose of the buildings and their use. Whereas the Duplicationist supplements the context with an invisible extra thing. — Andrew M

Again I refer to the problem implied in the 'reification of the subject'. To reify is to 'make into a thing', from the Latin 'res' (same term as used in 'res cogitans'). When you look for such a thing, there is nothing to be found, no 'invisible extra thing' - but at the same time, the reality of the subject is implicit in every act and utterance. (That is a topic much more discussed and debated in European philosophy than English-speaking, see this article).

Does a subject or being have uniform properties? — Harry Hindu

That is also a question that tends to reify the subject.

It interest me that in this discussion we get bogged down in parsing notions of realism and rarely explore the idea of mind-at-large, which seems to me to be unavoidable and a god surrogate. And when I say unavoidable, I am not referring to its reality but to it's explanatory power in idealism. Any thoughts on this? — Tom Storm

Related to the above, a difficulty is imposed on this question by 'the objective stance'. The objective stance, which basic to the natural sciences, seeks always to understand in objective terms - it is not concerned with reflective questions about the nature of the observing mind, for example (the extreme form being eliminativism). From within that perspective there's no such thing as 'mind at large' which also sounds suspiciously like a reification. But again, this doesn't consider the sense in which (as Schopenhauer said) that 'objects exist only in relation to subjects'. But to consider that properly means stepping outside the objective stance, which I think is actually quite a difficult thing to do.

Regardless, I'm interested the idea of 'life as the creation of mind'. On the one hand, I don't mean a design engineer deity who painstakingly creates the mechanisms of living things (e.g. Richard Dawkins' God). Maybe it is better understood, perhaps metaphorically, as an inchoate tendency in the universe at large towards self-awareness (although that will generally be rejected as orthogenetic).

On the other hand, the sense in which 'life is the creation of mind' refers to the way the mind/brain receives, organises and synthesises all of the data it receives into a meaningful gestalt. That is the constructive activity which comprises our life-world (lebenswelt or umwelt - compare Schopenhauer's 'vorstellung' or Buddhism's 'vijnana'). That's the approach I've been elaborating in this thread. If you really think it through, there is nothing outside of that, insofar as anything we consider will have been incorporated into it by the very act of considering it!

You're saying that in this, our Age of Mechanism, we give precedence to the physiological, and treat first person data like some sort of foam on top?

When the two are actually bound by their relationship in the opposition? — Tate

I’m saying what we call third personal , like physiological concepts, and ‘inner’ concepts like sensation, are the same ‘stuff’, and by stuff I don’t mean substances , either objective or mental. What I mean is that all experiences are interactions that are neither purely subjective nor objective They are inextricably both perspectival and about something. Every experience is a performance or act that is personally situated as relevant to me in some way , and the introduction of an outside element.

The GPS on my iPhone uses the equations of special relativity. Is that just a "linguistic convention and set of shared practices"?

That is the conceit of idealism: that all there is are such conventions. It disengages our narratives from the world. But it is only in their engagement with the world that these narratives are true or false. — Banno

True and false only make sense within a particular convention, that of truth as correctness and adequation with respect to a fixed external referent.
The concept of fixed external referent isnt a fact, it is a foregone conclusion and thus a starting point for most approaches to empiricism.
In other words, there is a hidden circularity at work here. It is the engagement of narratives with a world already articulated via such narratives that produces instances of truth and falsity. For alternative accounts of science practice, the aim of empirical investigation isnt truth as adequation but pragmatic usefulness in relation to the accomplishment of specified goals.

An airplane is designed to fly on the basis of specific aerodynamic engineering principles. Does this mean that only these principles will allow the plane to fly? If we were to imagine a history of flying machines extending indefinitely into the future and studied the evolution of their underlying engineering principles over the course of that history, what kind of pattern of change would we find? Would it be cumulative , with the earliest knowledge base being conserved and carried over into the subsequent modifications and improvements? Or would the evolution of the knowledge of flight be more like the periodic global realignment of an intricate tapestry or network of relations, maintaining a relative dynamic self-consistency in its overall form even as it undergoes continual mutations and transformations escaping any formula or algorithm?

Does this mean that only these principles will allow the plane to fly? — Joshs

No. But it does mean that not just any principles will allow the plane to fly.

So again, the idealist narrative is disengaged.

Sure, truth only makes sense with regard to a particular convention. After all it is statements that are true or false, and statements are conventions of language. You can say whatever you like, but only some of what you might say is of use.

Your suggest was :

Einstein’s work should neither be held up as the resolution of an error nor as proof of an error. Rather, it should be seen as an invitation to participate in a certain linguistic convention and set of shared practices. — Joshs

My reply is that the "convention" is what allows you to find your location with your iPhone. It's more than just a convention.

I suppose that's what you mean by "shared practices"?

truth only makes ense with regard to a particualr convention. After all it is statements that are true or false, and statements are conventions of language. You can say whatever you like, but only some of what you might say is of use. — Banno

Use is not necessarily the same thing as true. If a statement is a convention of language , then truth is a particular kind of conventional statement, which may differ from what is merely useful. A statement can be considered useful because it is true in the sense of corresponding with a state of affairs, or corresponding with facts supposedly external to the statement. Or it can be useful because it provides a way of organizing experience that is amenable to prediction and control. The predictive success of the statement, thanks to its underlying machinery of assumptions, need not be assumed to correspond to a state of affairs entirely external to it. Any particular statement and associated underlying paradigm may be assumed to be one of a potentially indefinite array of predictive vehicles, each of which may be ‘true’ of the same given event, that is , predictive, but in different ways. The different ways that a statement can be true would be a matter of HOW it organizes a set of events rather than a simple matter of correspondence between statement and event.

quote="Banno;711733"]the "convention" is what allows you to find your location with your iPhone. It's more than just a convention.[/quote]

The Einsteinian convention allows you to find your phone in a particular way. It works , not simply as true , but as true in its particular way of working. One could come up with a different way for a gps to work. This way wouldn’t be more true than the Einsteinian way, it would be a different way of being true.

Use is not necessarily the same thing as true. — Joshs

Sure.

The Einsteinian convention allows you to find your phone in a particular way. It works , not simply as true , but as true in its particular way of working. One could come up with a different way for a gps to work. This way wouldn’t be more true than the Einsteinian way, it would be a different way of being true. — Joshs

Again, that might be so, but not just any convention will do.

Only some of what one might say actually works. There is a way in which reality does not care what you say about it. Believe what you will, you cannot walk through walls.

I suspect you do not disagree with this.

What is it, then, that creates 'res actual' from 'res potentia' if not 'res cogitans' — Wayfarer

I think the authors answer that when they say...

measurement is a real physical process that transforms quantum potentiae into elements of res extensa, in a non-unitary and classically acausal process, and we offer specific models of such a measurement process.

Since they're not arguing that the two 'substances' (Aristotelian substances) are not causally connected in any way (only in a classical sense) then nothing prevents a purely physical effect of res actual effecting res potential.

Even if some as yet unspecified factor were required, it's bizarre to suggest this factor simply must be res cogita, as if it were the only remaining option, and it certainly doesn't "support" your position without this.

That coheres with the Platonist idea that number is real - not real as an object or 'something in the world' but as what Augustine calls 'an intelligible object'. — Wayfarer

No. If absolutely doesn't. The argument is that our classification of what is real needs to include possibility. It does not, in any way mean we now have free reign to just chuck in anything else we feel like into the category. The need to expand the set hasn't, mentioned at all whether number should be included in that newly expanded set.

It comes back to the question you still haven't answered. What criteria does a thing have to meet to be counted as 'real'?

As to the sense quantum objects don't obey the 'law of the excluded middle', this doesn't make logical principles any less real in their domain of application - but shows that logic is not all-encompassing or omniscient, that it has limits. — Wayfarer

But your only proof offered so far that number is real is its universality. If universality isn't one of the criteria for being in the set {real things} then what's to stop just anything from being a member of that set? Are Unicorns real? If not why not?

Fuchs argued, the wave function does not describe the world — it describes the observer. “Quantum mechanics,” he says, “is a law of thought.

Says nothing about the non-physical nature of this thought though.

The direct connection I theorize, and can observe, is the skin touching the tea cup, the hand grasping it, the arm lifting the hand, the light hitting the eye, and so on. — NOS4A2

Just begs the question. we're asking about the directness of the data stream from the cause of you thinking "That's a cup" to your thought "That's a cup".

The argument is that the object of your experience 'the cup' is produced indirectly from causes external to the Markov Blanket of the system constituting your experience of the cup. If you then simply declare those external hidden states to be unhidden you are declaring that the cup on the table actually forms a direct connection (no intervening nodes) to the system whose function you'd describe as 'experiencing the cup'.

You'd basically be denying everything neuroscience has discovered over the last decades which demonstrably shows that there is no such direct connection, that several data nodes lie between the cause of a sensation and the conscious experience of that sensation.

I can even prove it to you from afar, if you're willing to undertake a little experiment?

Look straight ahead at something about 3m away (a door knob or light switch works well). Shut one eye. Look up, then back down to the object. Nothing ought to move (if it does, have your eyes tested!), your experience is of a static room which you just briefly examined the ceiling of. Now look back at the same object. Shut one eye. Gently place your finger on the lower part of your eye (over the eyelid, not directly on the eyeball) and gently press. The object you're looking at will appear to move. Your experience is now of a moving object.

You just replicated with your finger the exact same process you initiated with your eye muscles the first time. The only difference is the means by which the eye moved, not the sensation it received from the external world. Your brain adjusted the information in the first to give you a static picture because it knows that eye muscle movements cause this 'wobble' and so it filters it out. In the second, it's not used to you moving your eye with your finger so it doesn't filter out the wobble. It makes a prior guess that the wobble is what's actually happening in the world.

If you were to do this experiment every day for several weeks your brain would start to filter out this wobble, it would improve its guess to better fit the prediction that the external room is generally static.

What this shows is that there is, without doubt, at least one process (a data node) between what you refer to as your experience of the cup and the cause of that experience (which we refer to as 'the cup').

Einstein’s work should neither be held up as the resolution of an error nor as proof of an error. Rather, it should be seen as an invitation to participate in a certain linguistic convention and set of shared practices. — Joshs

The problem is then what's left to be described as 'the resolution of an error'? Surely everything we'd previously described that way falls into the same camp, no? Which means we've just defined away the term 'error'. No longer in use. Seems a daft way to go about things, since we all quite happily use the word.

Far better to say that an "invitation to participate in a certain linguistic convention and set of shared practices" is just what "resolving an error" is, it's what it means when we use the term.

The trouble is, as ever, that you want to declare all that to be the actual state of affairs. You're claiming that the world is such that we only ever have differing models of what is the case, true or not, relative only to the internal assumptions of that model.

But "the world is such that we only ever have differing models of what is the case, true or not, relative only to the internal assumptions of that model" is itself a claim about the way the world is, and so suffers from the same problem. It's only true relative to it's own internal assumptions.

This means that - relative to it's own internal assumptions - it's also true that the world is such that our theories directly correspond to the external state of affairs and some are just right and others just wrong.

You're trying to have your cake and eat it, presenting, as true, a theory about how the world is which within it claims that there are no absolutely true theories about how the world is.

I'm not sure about Ryle's assessment of the University. Take the emergent complex behavior of ant colony and apply that to human social structures. There is something more than the organization structure of the colony or the university. — Marchesk

Would that be something that we are unable to describe using ordinary or specialized language? We describe human beings and their activities in terms of purpose, agency, sentience, and so on. Those qualities don't presuppose a Cartesian framework.

Again I refer to the problem implied in the 'reification of the subject'. To reify is to 'make into a thing', from the Latin 'res' (same term as used in 'res cogitans'). When you look for such a thing, there is nothing to be found, no 'invisible extra thing' - but at the same time, the reality of the subject is implicit in every act and utterance. (That is a topic much more discussed and debated in European philosophy than English-speaking, see this article). — Wayfarer

Restating without the subject/object terms, aren't you just saying that a human being is implicit in a human being's actions and utterances?

I think the authors answer that when they say... — Isaac

They add:

Space and time, or spacetime, is something that “emerges from a quantum substratum,” as actual stuff crystalizes out “of a more fluid domain of possibles.”

And even though a measurement is a physical act it’s also a cognitive one.

What criteria does a thing have to meet to be counted as 'real'? — Isaac

‘Quick! What *is* the aim of all science and all philosophy? Your time starts…..now.’

More seriously - consider something like the principles of logic, or Pythagoras’ theorem. We would generally agree that they are real, I hope - that they’re not simply ‘social constructs’ (as some here would say). In that sense, I’m realist. But they’re not material entities, in that they can only be grasped by a rational mind. Ergo - real but not material. That is all I’m claiming, and it’s not that radical a claim.

The argument is that our classification of what is real needs to include possibility. — Isaac

Right. But I think the question needs to be asked, in what sense do possibilities exist? If you’re referring to an actual existent, then it’s not a possibility. If you’re referring to something that might happen, then it’s not something that exists. So the ‘realm of possibility’ is somewhere between existent and non-existent. There are things that are outside the realm of possibility altogether, but there’s a range of things within that realm, but some of which will never materialise. So the interesting question is, in what sense are those existent? I think Heisenberg’s answer is interesting - as he says, sub-atomic particles -and let’s not forget, they are the purported fundamental units of existence - are on the boundary between existent and non-existent. When a measurement is taken, then you have a definite answer - “yes, there it is, it exists”. That is the reason why the ‘act of measurement’ is portentous in modern physics.

Restating without the subject/object terms, aren't you just saying that a human being is implicit in a human being's actions and utterances? — Andrew M

Implicit, and easily overlooked. Or even eliminated.

It's about Fitch's paradox. — Banno

Not sure how Fitch's paradox is relevant. Idealism doesn't entail that there are no unknown truths. There can be unknown mathematical or logical truths, for example, and these do not require an external material world.

Only some of what one might say actually works. There is a way in which reality does not care what you say about it. Believe what you will, you cannot walk through walls. — Banno

Idealism can allow for the mental stuff that exists to behave in a regulated way such that we can't will ourselves to experience whatever we want. We'll never experience ourselves walking through walls.

If it is true in an over-mind, it remains true in a mind. I don't see any accrued advantage in such speculation. — Banno

Then why bother with it? — Banno

I'm not sure of the relation between advantage and truth. It might very well be that there's no practical difference between idealism and materialism, but also that idealism is true.

And as for why one might think that idealism is more likely than materialism, perhaps it's something like an application of Occam's razor. Rather than there being both material and mental stuff, and the hard problem of consciousness, and with the existence of material stuff being inferred to explain the regularity of experience, there's just the mental stuff that is immediately apparent.

even though a measurement is a physical act it’s also a cognitive one. — Wayfarer

Absolutely. I'm not saying that the possibility of some 'spooky' action of res cogita is closed off as an explanation for QM 'spookiness'. I'm just saying this article neither advances it either. Basically the metaphysical question behind measurement remains entirely untouched. What they do say is that there exists an explanation of QM 'spookiness' which does not require something like res cogita. Measurement can be just a physical process and that can be enough to actualise probabilities from their res potentia.

As so often the case, the evidence underdetermines the theories and so we have to look to other reasons to choose one over another - elegance, simplicity, personal preference...

consider something like the principles of logic, or Pythagoras’ theorem. We would generally agree that they are real, I hope — Wayfarer

Yes, I'd agree they're real, but only in the same way unicorns are real. It's a thing in our world we talk about and make use of. The point is what kind of thing they are - unicorns are a real mythical invention: the kind of thing they are is 'mythical invention'. Logic is a real mode of thinking, that doesn't mean it would still be the same absent of humans to think that way.

In other words, a ...

‘social construct — Wayfarer

...is perfectly real.

Hence the 'radicalness' of your claim, to the extent there is is any, is that social constructs and the laws of logic are two different kinds of thing. Whether we distinguish them by calling one real and the other not, or whether we distinguish them by saying they're both real but of different kinds, is semantic. what matters is the role they thereby have in our behaviour.

Yes, I'd agree they're real, but only in the same way unicorns are real. — Isaac

Fictional creatures and mathematical principles are both things that can only be grasped by a mind, but mathematics possesses a kind of reality which I’m sure you will agree doesn’t pertain to fairy tales.

mathematics possesses a kind of reality which I’m sure you will agree doesn’t pertain to fairy tales. — Wayfarer

Mathematics serves a different function to unicorns (the concept of), but I don't know if that makes it possess a different "kind of reality". Again, I think that would depend on the baggage that came along with that. How does something which possesses a "different kind of reality" differ from something which is merely different?

Say, a dog is different from a cat. Does a dog possess a different kind of reality from a cat, or are they too similar to qualify? What kind of work is this classification doing - essentially is what I'm asking.

aren't you just saying that a human being is implicit in a human being's actions and utterances?
— Andrew M

Implicit — Wayfarer

:up:

Do you apply that to mathematical and logical statements as well?

How does something which possesses a "different kind of reality" differ from something which is merely different? — Isaac

At last you see the question I'm asking.

I think that classical philosophy understood there are different levels or modes of being - an hierarchy of being, expressed in The Republic through the analogy of the divided line. And I'm not saying that just out of nostalgia or sentiment - my belief is that this represents a real set of distinctions which has been lost in the transition to modernity. It corresponds with the loss of the 'realm of value' which is the vertical dimension, as distinct from the horizontal dimension assumed by the natural sciences.

What kind of work is this classification doing - essentially is what I'm asking. — Isaac

This is still visible in early modern philosophy, in which the reality of things is judged in terms of their proximity to the source of being. So the aim of the understanding of that is the 'philosophical ascent' to the ground of being. If it sounds religious, that's because Christian theology absorbed a great deal of it from Platonist philosophy, but it's not religious in the dogmatic sense.

In contrast to contemporary philosophers, most 17th century philosophers held that reality comes in degrees—that some things that exist are more or less real than other things that exist. At least part of what dictates a being’s reality, according to these philosophers, is the extent to which its existence is dependent on other things: the less dependent a thing is on other things for its existence, the more real it is. — IEP

So, the connection I see with Heisenberg's physics, is that it represents the re-discovery of the idea of 'degrees of reality' - which has what had been lost. There is no conceptual scale in modern philosophy, of greater or lesser degrees of reality. Things either exist or they do not. And the loss of that goes back centuries to long-forgotten scholastic debates about the univocity of being (and also the loss of formal and final causation.)

Do you apply that to mathematical and logical statements as well? — Andrew M

The Galilean/Cartesian/Newtonian science that underwrote the scientific revolution concentrated exclusively on the quantitative aspects of bodies - just those attributes which can be represented in Monsieur Descartes' wonderful algebraic geometry. The qualitative aspects were relegated to the subjective consciousness of the observer (as per the last quote on my profile page.) This is the origin of the 'absence of the subject' - the subject was at best a tacit presence, the detached scientific eye, practicing a kind of detachment that was actually inherited from the more religiously-focussed detachment of the mystics, but in this context concentrated wholly on the 'domain of quantity'. But none of that undermines the ability of the rational mind to plumb the depths of reality through mathematical reasoning. It just puts it in a social context.

It's as if the West took all the parts of Plato that were useful for engineering and science, but left behind the entire ethical content of the search for 'the Good'.

I’m saying what we call third personal , like physiological concepts, and ‘inner’ concepts like sensation, are the same ‘stuff’, and by stuff I don’t mean substances , either objective or mental. What I mean is that all experiences are interactions that are neither purely subjective nor objective They are inextricably both perspectival and about something. Every experience is a performance or act that is personally situated as relevant to me in some way , and the introduction of an outside element. — Joshs

Third person data is is things like "The moon orbits the earth." Would you agree that this statement is true from any perspective?

Idealism doesn't entail that there are no unknown truths. — Michael

When you can, take a look at the SEP article on Fitch's paradox. "...the proof does the interesting work in collapsing moderate anti-realism into naive idealism."

The article doesn't explain why idealism entails that there are no unknowable truths, it just asserts that it does.

Do you believe that there are unknowable mathematical truths? If so, why would this only be the case if there is an external material world? I don't see why the existence of mind-independent atoms determines the provability of Goldbach's conjecture, for example.

Or what about counterfactuals or claims about the future? They can be unknowable if there's an external material world but are necessarily knowable if there isn't? I don't see how that follows.

I think that classical philosophy understood there are different levels or modes of being — Wayfarer

This seems to be the crux of our disagreement, and I seem to recall reaching it before (not that it's a bad thing to do so again, clarity is always useful). You use "understand" here in a way which I think is unjustified. Classical philosophy said there are different levels or modes of being. They only understood there are different levels or modes of being if you already agree with the conclusion. Otherwise it begs the question.

We're asking if there actually are different levels or modes of being, and you're offering, by way of evidence, that somebody once said that there were.

I understand that such a philosophical position existed. I'm passing familiar with the historical changes by which it fell out of favour. Nothing in either the fact that it once existed, nor in the fact that sociopolitical factors caused its decline stand as arguments in favour of the model.

We've agreed (I think) that the evidence we have (of any sort, empirical or otherwise) under determines the theories. So why choose this one? What are its merits?

But I think the question needs to be asked, in what sense do possibilities exist? — Wayfarer

The answer to this question depends on how one understands the nature of time. Obviously, the future consists of possibilities, that's why we deliberate before acting, because we can decide which possibilities to actualize. The future consists of possibility, and this is known as that which is between existent and non-existent, because we assign "existence" to material things, and future things have not yet materialized.

There is however, a trend in modern culture, to deny the reality of "the present" in time. This denial is to ignore the distinction between past and future, rendering the principles by which we understand "possibility" as unintelligible. Of course this denial of "the present" as a real division between two completely distinct aspects of reality, the past and the future, is completely opposed to the way that all of us live our lives. So this is the ultimate in extreme forms of hypocrisy. We all live, act, and think, in complete acceptance of a real difference between things of the past and things of the future, in all of our mundane activities, so to deny the reality of the present, as the necessary division between these two completely different aspects of reality, is an extreme form of hypocrisy.

Measurement can be just a physical process and that can be enough to actualise probabilities from their res potentia. — Isaac

What exactly does this mean, "to actualize probabilities"? If possible things have no material existence, and actual things are material things, then what does it mean to give materiality to a thing?

This is the question of "the present". At "the present", which is arguably the time of our experience, and observations, future things have no material existence, being possibilities, and past things are things which have materialized with actual existence. At "the present", something happens whereby immaterial things (possibilities) are "actualized" into real material existents. What could be this process where immaterial possibilities are actualized into real material things, other than some form of "being chosen"?

That choice of words, "being chosen", was made to demonstrate the traditional understanding, that the actualization of possibilities, at the moment of the present, is caused by "the Will of God".

the actualization of possibilities, at the moment of the present, is caused by "the Will of God". — Metaphysician Undercover

I've absolutely no interest in a God-of-the-gaps argument. Even if there were an uncertainty to resolve around the means by which potential states become actual states it would a) be best resolved by experts in that field, and b) have absolutely nothing to do with a character from some 2000 year old folk story.

Classical philosophy said there are different levels or modes of being. They only understood there are different levels or modes of being if you already agree with the conclusion. Otherwise it begs the question. — Isaac

Correct.

We're asking if there actually are different levels or modes of being, and you're offering, by way of evidence, that somebody once said that there were. — Isaac

Apart from the many other arguments which you here disregard.

What are its merits? — Isaac

It is what philosophy is about. And I completely understand that mine is a minority view.

When you speak of 'evidence', surely you grasp that in this case, empirical evidence is not a question at issue, but that the relevance of it to this issue is one of the claims at stake.

The word that comes to mind most readily in respect of your line of questioning is 'eristic'.

Apart from the many other arguments which you here disregard. — Wayfarer

I don't think any have been presented. They always, on interrogation, seem to come down to "Plato said so". I've responded to everything you've written and you to me likewise. We've had a fairly exhaustive discussion. I don't recall anything being left by the wayside, but if I've missed an argument I'm all ears...

It is what philosophy is about. — Wayfarer

It reads like an an answer, not a question. Are you saying that, for you, philosophy is about the fact that there are different levels or modes of being? What are the merits of seeing philosophy as having such a narrow remit?

When you speak of 'evidence', surely you grasp that in this case, empirical evidence is not a question at issue, but that the relevance of it to this issue is one of the claims at stake. — Wayfarer

I do, yes. That's why I put in the caveat "...or otherwise".

Yes. What's wrong with: brain activity is sensations? — bongo fury

When observing another's brain activity, how can you tell if the visual sensation you experience of another's brain activity is your own brain activity or theirs?

The issue is that other people's brain activity can only be observed via your sensations. If the sensations are an illusion then so is your understanding of brain activity. You don't experience brain activity when observing your own sensations. You only experience sensations of which your observations of other people's brain activity is composed of. When observing others' sensations you experience brain activity. So there is a contradiction that needs to be resolved. It seems to me that brain activity is secondary to sensations as my own sensations are not composed of brain activity. It's the other way around.

Again I refer to the problem implied in the 'reification of the subject'. To reify is to 'make into a thing', from the Latin 'res' (same term as used in 'res cogitans'). When you look for such a thing, there is nothing to be found, no 'invisible extra thing' - but at the same time, the reality of the subject is implicit in every act and utterance. (That is a topic much more discussed and debated in European philosophy than English-speaking, see this article).

Does a subject or being have uniform properties?
— Harry Hindu

That is also a question that tends to reify the subject. — Wayfarer

But it's not. It is your own use of language that reifies subject and being. Are subject and being simply scribbles you've put on this screen, or do the scribbles refer to something that isn't scribbles? If the latter, then what is it the scribbles refer to? Or are you saying that there is no distinction between subject and non-subject? If that is what you're saying then you haven't actually said anything useful. It seems more like how Christians explain that their God is undefinable and not a thing that can be accessed by science in an effort to protect the idea of God from being falsified. You're doing the same thing here in regards to subject and being.

You say this extra thing cannot be found and then say it is implicit in every act and utterance. Then subject and being are the acts of humans?

Idealism is "true" (or internally coherent some such thing) and most often rather irrelevant to our human experience of being in the world. Materialism is often quite crude and illogical and most often utterly relevant and practical to our experience of being in the world. Anyway, pox on this dichotomy. They both are pretty true and coherent approaches, simultaneously and easily. There is no true contradiction between idealism and materialism. There cannot be.