Metaphors are commonly used in science — RussellA

Not all of those are metaphorical. I can't see how Newton's equations of motion are metaphorical, although I agree that many of the other examples are. There are also such things as 'rogue metaphors' that have become deeply embedded in cultural discourse but have assumed many meanings that they may not have originally carried. I think evolutionary biology is rife with 'em.

The fact that I can codify and quantify using reason, logic and mathematics the "laws of nature" that I observe on the train, and still be applicable on the far side of the universe, is not a measure of success of my reasoning, logic and mathematics, but rather is a measure of the regularity and invariance of the "laws of nature".

Without such regularity and invariance in "the laws of nature", our reasoning, logic and mathematics would count for nothing.

IE, mathematics is only effective because of the unreasonable regularity in the "laws of nature" — RussellA

That sounds right. If nature were more chaotic, we might still have a rich 'science of formal systems,' but this would probably have little interest or prestige apart away from its specialists.

We learn by observing nature. Then we take those observations and extract their essences.

I can't see how Newton's equations of motion are metaphorical, — Wayfarer

Newton's second law F=ma is a metaphor, not a literal fact.

Andrew May makes a strong point that even Newton's second law is a metaphor, in that that when a body is acted upon by a force, the time rate of change of its momentum equals the force, in that F=ma,

Andrew May Metaphors in Science 2000
"In his article on the use of metaphors in physics (November issue, page 17), Robert P Crease describes several interesting trees but fails to notice the wood all around him. What is a scientific theory if not a grand metaphor for the real world it aims to describe? Theories are generally formulated in mathematical terms, and it is difficult to see how it could be argued that, for example, F = ma "is" the motion of an object in any literal sense. Scientific metaphors possess uniquely powerful descriptive and predictive potential, but they are metaphors nonetheless. If scientific theories were as real as the world they describe, they would not change with time (which they do, occasionally). I would even go so far as to suggest that an equation like F = ma is a culturally specific metaphor, in that it can only have meaning in a society that practices mathematical quantification in the way that ours does. Before I'm dismissed as a loopy radical, I should point out that I'm a professional physicist who has been using mathematical metaphors to describe the real world for the last twenty years!"

The equation F=ma cannot be literal because of Hume's problem of induction. Through logic and reason and the empirical observation of constantly conjoined events, we hypothesise that F=ma. Through further empirical observation we discover that this equation proves to be effective in the prediction of future states of affairs. We believe the equation to be literal, but this belief is only a hypothesis.

We believe, we hypothesise, that there is a regularity in what we call the "laws of nature", and accordingly create a mathematics also founded on regularity in the expectation that the regularities in our mathematics will correspond with the regularities in the "laws of nature". That our mathematics are effective in predicting future states of affairs in the world infers that our hypothesis that there are regularities in the laws of nature is correct, is true. But, this is not knowledge, as our hypothesis can never be proved, only a justified belief.

A metaphor may be defined as i) a figure of speech in which a word or phrase is applied to an object or action to which it is not literally applicable and ii) a thing regarded as representative or symbolic of something else.

IE, as the equation F=ma can never be proved to be a literal description of states of affairs in the world, and must always remain a hypothesised representation, it falls within the definition of metaphor.

Yeah, no. Not buying.

Aren’t you the one supposed to be defending realism? :smile:

Yeah, no. Not buying. Aren’t you the one supposed to be defending realism? — Wayfarer

Luckily, my livelihood is not dependent on my selling.

I believe in Realism
Idealism is the view that things exist only as ideas, with no reality of material objects outside of the mind. Realism is the view that objects exist in themselves, independently of our consciousness of them. My position is not that of Idealism, as I believe objects exist in themselves, independently of our consciousness of them. It comes down to exactly what "objects" are. My belief that elementary particles and elementary forces do ontologically exist in a mind-independent world, though relations don't, is consistent with Realism.

Do you believe in Realism or Idealism ?
As you wrote on page 3: "Ever since I began to think about it, I've held that numbers and basic geometrical principles and the like are real, in that they're the same for anyone who can grasp them. So they're not dependent on your or my mind, but can only be grasped by a rational mind." It would follow from your position that if numbers are real and not dependent on your or my mind, then there must be a mind-independent world." This is a belief in Realism.

Yet you also wrote on page 3: "I question the coherence of the idea of a 'mind-independent world'. This is a belief in Idealism."

Are these positions compatible ?

We learn by observing nature. Then we take those observations and extract their essences. — jgill

Like a spider! :chin:

Idealism is the view that things exist only as ideas, with no reality of material objects outside of the mind. — RussellA

It's a rather simplistic description. Philosophical idealism can accept that material objects and forces have a degree of reality, and that they're not mere phantasms or delusions. In that sense, they're not 'in the mind' in the way that expression would usually be understood. An idealist philosopher will understand that she will be scalded by hot water or cut by a razor. So she may not hold that things only exist 'in the mind' in a simplistic or obvious sense, but that the constructive activities of the mind are foundational to our knowledge of the world, and that we can't go beyond that to see things 'as they are in themselves'. That was nearer to Kant's view.

It would follow from your position that if numbers are real and not dependent on your or my mind, then there must be a mind-independent world." — RussellA

But numbers and logical principles can only be understood by a mind capable of counting and reasoning. So they're real, but they're not material objects like rocks or trees.

The view that abstract objects are real is generally associated with Platonism or scholastic realism. But you've already indicated that you reject this with reference to F H Bradley's argument.

My claim that numbers and logical principles are real independently of our minds, but can only be grasped by a mind, is closer to traditional realism than to scientific realism.

But:

My belief that elementary particles and elementary forces do ontologically exist in a mind-independent world — RussellA

This is just what has been called into question by 20th Century physics, specifically the Bohr-Einstein debates. Now obviously that is a deep issue - in fact this whole issue is deep - but the thrust of the 'quantum revolution' was succinctly expressed by Werner Heisenberg, when he said:

We can no longer speak of the behaviour of the particle independently of the process of observation. As a final consequence, the natural laws formulated mathematically in quantum theory no longer deal with the elementary particles themselves but with our knowledge of them. Nor is it any longer possible to ask whether or not these particles exist in space and time objectively … When we speak of the picture of nature in the exact science of our age, we do not mean a picture of nature so much as a picture of our relationships with nature. …Science no longer confronts nature as an objective observer, but sees itself as an actor in this interplay between man and nature. The scientific method of analysing, explaining and classifying has become conscious of its limitations, which arise out of the fact that by its intervention science alters and refashions the object of investigation... — The Physicists Conception of Nature

So, this questioning of the 'mind-independent' nature of the supposed fundamental constituents of existence - namely, atomic particles - really has undermined many forms of realism. It was this which was at the heart of Einstein's discomfort - as a staunch scientific realist he could never accept the so-called 'observer dependent' nature of quantum physics. But I believe, as has been discussed in various other threads, that experimental evidence has confirmed Heisenberg's approach - 'the Copenhagen interpretation' - over the realist view.

For this reason, there is actually a kind of idealist streak in a lot of modern scientists. Not all, by any means, and a long way from unanimously, but it's there to be found.

"The doctrine that the world is made up of objects whose existence is independent of human consciousness turns out to be in conflict with quantum mechanics and with facts established by experiment." ― Bernard d'Espagnat

"We have to give up the idea of realism to a far greater extent than most physicists believe today." ― Anton Zeilinger

“The atoms or elementary particles themselves are not real; they form a world of potentialities or possibilities rather than one of things or facts. ― Werner Heisenberg

and so on.

Philosophical idealism can accept that material objects and forces have a degree of reality — Wayfarer

Some have said that "definitions are not all that helpful", but it has also been said about Ordinary Language Philosophy that traditional philosophical problems are rooted in misunderstandings philosophers make by distorting or forgetting how words are ordinarily used to convey meaning in non-philosophical contexts. Such philosophical use of language creates the very philosophical problems they are employed to solve.

Idealism may be simply defined as a belief that there is no mind-independent external world. Realism that there is a mind-independent external world. Within Realism is Direct Realism and Indirect Realism. Direct Realism may be simply defined as the belief that we directly observe objects in the external world as they really are. Indirect Realism may be simply defined as the belief that we only observe representations of objects we believe to be in the external world. Kant was an Indirect Realist.

IE, it is true that Idealism accepts that material objects and forces have a degree of reality, but that reality is in the mind, not in a mind-independent world.

The view that abstract objects are real is generally associated with Platonism or scholastic realism. But you've already indicated that you reject this with reference to F H Bradley's argument. — Wayfarer

The Platonist believes in the existence of abstract objects, where abstract objects exist outside time and space, are not causal and are necessary. The Nominalist believes in concrete objects, where concrete objects exist in time and space, are causal and are contingent.

It is still possible for the Nominalist to reject the Platonism of abstracts while still believing in the ontological existence of relations.

I personally reject the Platonism of abstracts because I find the idea of objects existing in the external world outside of time and space incomprehensible.

For a similar reason, I also reject the ontological existence of relations, as they also exist in the external world outside of time and space.

My belief that elementary particles and elementary forces do ontologically exist in a mind-independent world — RussellA

This is just what has been called into question by 20th Century physics — Wayfarer

The age of the universe is about 13.8 billion years, and human intelligence has been on the Earth for about 7 million years. That a mind-independent world existing 13,793 billion years before the arrival of human observers has been called into question makes no sense to me. It brings to mind the belief of Young Earth Creationism, whereby lifeforms were created in a supernatural act about 6,000 to 10,000 years ago.

I am also sure that most contemporary philosophical interest in the quantum world is comparable to that of medieval discussion about the philosopher's stone and its relevance to alchemy.

Kant was an Indirect Realist. — RussellA

Not so. His philosophy is described as transcendental idealism although I daresay your simplistic definitions would render the distinction unintelligible.

I personally reject the Platonism of abstracts because I find the idea of objects existing in the external world outside of time and space incomprehensible. — RussellA

That's because you're trying to imagine an external world outside space and time, as 'a place', where 'things' never change. But the subject of the analysis are purely intelligible in nature, i.e. they can only be grasped by a mind, so they don't exist in the way that sensory objects exist. They are inherent in the scheme of things, rather than existing as manifest phenomena. But because our culture is so deeply indoctrinated to think only in phenomenalist terms, it's an impossible distinction to grasp.

The age of the universe is about 13.8 billion years, and human intelligence has been on the Earth for about 7 million years. — RussellA

I can see you're not educated about the philosophical implications of physics. And I can also see why you believe it doesn't make sense, but then, that is why some of the greatest minds of the last century have been perplexed, and still are perplexed, by these very same issues. (See Does the Universe Exist if We're Not Looking?, Discover Magazine.)

Perhaps we need a good thread on understanding idealism (as opposed to debating it). Personally I found Bernardo Kastrup's conceptual framing of the subject much more helpful than others I have read.

It would take a book.

It would take a book. — Wayfarer

Sounds like you are not hopeful then.

As you notice, I go into bat for idealism in almost every thread I participate in. But it's such a big subject - I tried to sit down and draft an OP for it, and it quickly became obvious that it was going to be several thousand words. (And I've just shelled out on the rather expensive e-book edition of the link above, mainly to help me bring into focus exactly what form of idealism to comment on.)

As a mathematician who never gave much thought to Platonic ideals, my rather superficial view is that these ideals do not exist in any sort of physical forms, but exist in an abstract space that is accessible to human minds, in much the same way that spaces of functions exist in the normal mathematical realm. Abstractions from reality are commonplace in math.

You will notice that the most frequent objection to idealism is the assumed reality of objects, the objective domain, the sensory realm. Everything is premissed on that assumption, and must be ultimately derived from that, even though, on analysis, the actual nature of the objective realm, which is assumed to be self-evidently real, is one of the major points at issue!

The fundamental absurdity of materialism is that it starts from the objective and takes as the ultimate ground of explanation something objective , whether it be matter in the abstract, simply as it is thought, or after it has taken form, is empirically given—that is to say, is substance, the chemical element with its primary relations. Some such thing it takes, as existing absolutely and in itself, in order that it may evolve organic nature and finally the knowing subject from it, and explain them adequately by means of it; whereas in truth all that is objective is already determined as such in manifold ways by the knowing subject through its forms of knowing, and presupposes them; and consequently it entirely disappears if we think the subject away. Thus materialism is the attempt to explain what is immediately given us by what is given us indirectly. All that is objective, extended, active—that is to say, all that is material—is regarded by materialism as affording so solid a basis for its explanation, that a reduction of everything to this can leave nothing to be desired (especially if in ultimate analysis this reduction should resolve itself into action and reaction). But we have shown that all this is given indirectly and in the highest degree determined, and is therefore merely a relatively present object, for it has passed through the machinery and manufactory of the brain, and has thus come under the forms of space, time and causality, by means of which it is first presented to us as extended in space and ever active in time. From such an indirectly given object, materialism seeks to explain what is immediately given, the Idea (in which alone the object that materialism starts with exists), and finally even the will from which all those fundamental forces, that manifest themselves, under the guidance of causes, and therefore according to law, are in truth to be explained. — Arthur Schopenhauer, World as Will and Representation

As a mathematician who never gave much thought to Platonic ideals, my rather superficial view is that these ideals do not exist in any sort of physical forms, but exist in an abstract space that is accessible to human minds, in much the same way that spaces of functions exist in the normal mathematical realm. — jgill

Gödel was a mathematical realist, a Platonist. He believed that what makes mathematics true is that it's descriptive—not of empirical reality, of course, but of an abstract reality. Mathematical intuition is something analogous to a kind of sense perception. In his essay "What Is Cantor's Continuum Hypothesis?", Gödel wrote that we're not seeing things that just happen to be true, we're seeing things that must be true. The world of abstract entities is a necessary world—that's why we can deduce our descriptions of it through pure reason. — Rebecca Goldstein

As you notice, I go into bat for idealism in almost every thread I participate in. But it's such a big subject — Wayfarer

I understand entirely. I think there's room for some quality prompts on the subject, especially common fallacies or misrepresentations. Sometimes 3 or 4 key ideas highlighted with some recommended readings are helpful to others. And it could be done rolled out over several posts.

I am fascinated that one of the key aspects of the Western philosophical tradition is often poorly understood or abandoned and I say this as someone who is not an idealist. Frankly, I couldn't say how one could ascertain whether idealism is the case or not. Nevertheless I am very interested in basic delineations of this approach.

Arthur Schopenhauer, World as Will and Representation — Wayfarer

Yes - it's a great quote.

Sometimes 3 or 4 key ideas highlighted with some recommended readings are helpful to others. — Tom Storm

Good idea. I had started something but side-tracked myself. Now that I have that book, I might use it as a base.

See. That's spooky. :D

Kant.......His philosophy is described as transcendental idealism — Wayfarer

The term "Transcendental Idealism" is more metaphorical than literal

A better description than "transcendental idealism" could be "justified belief within Indirect Realism" in that we hypothese the cause of representations discovered in phenomena from the senses using justified belief.

A wave function collapses when a wave function reduces to a single eigenstate due to an interaction with the external world. The fact that this interaction is called an "observation" does not mean the observer has to be a conscious being. It can be a particle of light, a molecule of air, a wall, a ceiling, a window, etc.

"Observation" is being used as a metaphor in that only conscious beings can observe. A rock cannot observe the air, the tree cannot observe the wind, etc. That wind howls does not mean that wind is in anguish. That a wave of terror washed over him does not mean that terror is a wave. That to say that Jess is dynamite does not mean she is made of dynamite.

It is true that Kant as an Indirect Realist believed in Epistemological Idealism, but it is certainly not true that he believed in Ontological Idealism.

IE, the fact that Kant's philosophy is called "transcendental idealism" does not of necessity mean that it can be described as either transcendental or Idealism.

abstracts.........But the subject of the analysis are purely intelligible in nature, i.e. they can only be grasped by a mind, so they don't exist in the way that sensory objects exist. — Wayfarer

I agree that abstracts can only be grasped by the mind.

The question that remains to be answered is how can something exist in a mind-independent world outside of time and space ?

(See Does the Universe Exist if We're Not Looking?, Discover Magazine.) — Wayfarer

Can anyone make a valid argument that a mind-independent world did not exist in the 13 billion years before the arrival of human observers ?

There is an interview with John Wheeler Does the Universe Exist if We're Not Looking

We inhabit a cosmos made real by our own observation

John Wheeler has a gut feeling that we inhabit a cosmos made real by our own observation.

The article notes that "When physicists look at the basic constituents of reality— atoms and their innards, or the particles of light called photons— what they see depends on how they have set up their experiment."

In addition "Our observations, he suggests, might actually contribute to the creation of physical reality. To Wheeler we are not simply bystanders on a cosmic stage; we are shapers and creators living in a participatory universe."

IE, from the standpoint of Epistemological Idealism within Indirect Realism, I agree with the above, and I am sure that not only Kant but also Schopenhauer would as well.

Are humans necessary for the existence of the universe

The article also asks "Does this mean humans are necessary to the existence of the universe? While conscious observers certainly partake in the creation of the participatory universe envisioned by Wheeler, they are not the only, or even primary, way by which quantum potentials become real. Ordinary matter and radiation play the dominant roles.........In this case the mica, not a conscious being, is the object that transforms what might happen into what does happen."

IE, the article raises the question "Does the Universe exist if we're not looking", and its answer is yes.

The term "Transcendental Idealism" is more metaphorical than literal — RussellA

According to the source document:

I understand by the transcendental idealism of all appearances the doctrine that they are all together to be regarded as mere representations and not things in themselves, and accordingly that space and time are only sensible forms of our intuition, but not determinations given for themselves or conditions of objects as things in themselves. To this idealism is opposed transcendental realism, which regards space and time as something given in themselves (independent of our sensiblity). The transcendental realist therefore represents outer appearances (if their reality is conceded) as things in themselves, which would exist independently of us and our sensibility and thus would also be outside us according to pure concepts of the understanding. — CPR A369

However, Kant then grants that you can be both a transcendental AND an empirical realist:

The transcendental idealist, on the contrary, can be an empirical realist, hence, as he is called, a dualist, i.e., he can concede the existence of matter without going beyond mere self-consciousness and assuming something more than the certainty of representations in me, hence the cogito ergo sum. For because he allows this matter and even its inner possibility to be valid only for appearance – which, separated from our sensibility, is nothing – matter for him is only a species of representations (intuition), which are call external, not as if they related to objects that are external in themselves but because they relate perceptions to space, where all things are external to one another, but that space itself is in us. — CPR A370

So, Kant is not denying the apparent reality of the empirical domain, but that it has intrinsic or inherent reality.

Can anyone make a valid argument that a mind-independent world did not exist in the 13 billion years before the arrival of human observers ? — RussellA

The problem is philosophical, not scientific. You're taking the scientific realist view as an absolute description. In other words, you're not seeing the role that the mind plays in constructing the picture of the world - even of the world prior to the advent of human consciousness. In that sense, even the most apparently-obvious scientific hypotheses are mental constructions. They may be accurate mental constructions, which can be tested against all manner of observations, but the mind has an inextricable role in their construction. Have a look again at this quote.

John Wheeler has a gut feeling that we inhabit a cosmos made real by our own observation. — RussellA

It's more than a 'gut feeling'. Wheeler was one of the giants of theoretical physics. In terms of popular science, he is known for this theory of the 'participatory universe'. It's about a lot more than simply what happens in an experiment.

IE, from the standpoint of Epistemological Idealism within Indirect Realism, I agree with the above, and I am sure that not only Kant but also Schopenhauer would as well. — RussellA

That's because you have in your mind the firm belief in an external reality. I understand that questioning that belief is difficult.

However, Kant then grants that you can be both a transcendental AND an empirical realist: — Wayfarer

As you wrote about Kant's theory of "Transcendental Idealism": "you can be both a transcendental AND an empirical realist", this indicates the phrase "Transcendental Idealism" should be treated as a figure of speech rather than something to be taken literally.

In my terms, Kant's phrase "Transcendental Idealism" includes both Epistemological Idealism and Ontological Realism. The problem is, how to link them ?

For the Ontological Idealist, ie for those not believing in the ontological existence of a mind-independent world, this is not a problem, as there is no "Ontological Realism".

However, for the Ontological Realist, it does remain problematic.

We can only ever have knowledge of representations in our mind. The belief that something mind-independent caused them we can justify in various ways. However, if we can never have knowledge of what caused these representations, we can never know that our belief is true.

For example, I have subjective knowledge of the colour red. I believe it was caused by a wavelength of 700nm. I can justify this using scientific procedures, but as science itself is founded on representation, a science founded on representation is incapable of getting behind the representations themselves.

David Stove's Discovery of the Worst Argument in the World addressed this problem, raising the inevitable conclusion that there is no way to get out.

IE, many justifications can be made for our belief in a mind-independent world, but none
as far as I know beyond doubt. One can only say that from the weight of evidence there is most likely a mind-independent world, and perhaps pragmatically that is all one needs.

even the most apparently-obvious scientific hypotheses are mental constructions — Wayfarer

As my belief is that of Indirect Realism, I agree.

That's because you have in your mind the firm belief in an external reality. I understand that questioning that belief is difficult. — Wayfarer

It is true that I find it impossible to question the ontological existence of a mind-independent world.

Otherwise I would find it difficult to fill the kettle with water, switch on the kettle and put a tea bag into my cup if I didn't think these things were real and not a figment of my imagination.

Otherwise I would be diagnosing myself as schizophrenic, hallucinating about things that are not really there.

Otherwise, I would be diagnosing myself as having Dissociative Identity Disorder, in having long conversations about science and philosophy with myself, between two distinct personalities both existing in my mind.

IE, my sanity requires me to believe that I am interacting with a world that is mind-independent.

Otherwise I would find it difficult to fill the kettle with water, switch on the kettle and put a tea bag into my cup if I didn't think these things were real and not a figment of my imagination. — RussellA

All due respect, you're misunderstanding what idealism means. Idealists do not think that the world is a figment of the imagination, although if you believe that is what they think, then I'm probably unable to set you straight on that.

David Stove's Discovery of the Worst Argument in the World addressed this problem, raising the inevitable conclusion that there is no way to get out. — RussellA

I studied David Hume under David Stove as an undergrad. I liked Stove and respected him, but I'm afraid that his 'Gem' is rather a caricature. I mean, yes, there are those who abuse the kinds of arguments that Stove has in his sights, but there is a genuine philosophical insight that I think Stove is somehow missing. See this critique of 'Stove's Gem' (and I knew that writer, too - he's known for his writings on Aristotelian philosophy of maths).

As you wrote about Kant's theory of "Transcendental Idealism": "you can be both a transcendental AND an empirical realist", this indicates the phrase "Transcendental Idealism" should be treated as a figure of speech rather than something to be taken literally. — RussellA

That's really not the case, but I grant, it is a very hard idea to fathom. See this primer.

Idealists do not think that the world is a figment of the imagination — Wayfarer

There are different kinds of Idealism.

For example, as described by the SEP - Idealism, there is Berkeley's "Ontological Idealism", where the mind is the ultimate foundation of all reality, or even exhaustive of reality, and there is Kant's "Epistemological Idealism", where Idealism is not about any existence of things but only our representation of them.

IE, some Idealists think the world is a figment of the imagination.

there is a genuine philosophical insight that I think Stove is somehow missing — Wayfarer

Berkeley's argument "the mind....is deluded to think it can and does conceive of bodies existing unthought of, or without the mind, though at the same time they are apprehended by, or exist in, itself" may be countered by common sense justifications.

"RussellA - Transcendental Idealism" should be treated as a figure of speech.............That's really not the case — Wayfarer

"Transcendental Idealism" does not address Stove's problem

Kant's "transcendental" is about a priori pure and empirical intuitions. Kant's "Epistemological Idealism" is not about any existence of things but only our representation of them.

The expression "transcendental idealism" can only be a figure of speech as it is about more than the transcendental and idealism, in that it does not include any reference to the world of the noumena, an important part of Kant's theory.

Experiencing certain phenomena through my senses, I have subjective knowledge of the colour red. I was born with the innate ability to perceive the colour red. "Transcendental idealism" is the combination of my innate ability to perceive red and my perceiving the colour red.

Using reason, understanding and imagination, I arrive at the belief that my perception of red was caused by light in the external world having a wavelength of 700nm. This light having a wavelength of 700nm is Kant's noumena.

IE, Kant's "Transcendental Idealism" does not address the problem of how we are able to know what precedes, if anything, our phenomena.

We learn by observing nature. Then we take those observations and extract their essences. — jgill

I'm with you in spirit, but perhaps we dream up those essences and only later learn to check if they or their implications are compatible with observations.

We can only ever have knowledge of representations in our mind. — RussellA

This might be truish but seems like 'bachelors are unmarried men.' There's also the problematic issue of 'private knowledge' (Cartesian baggage). I suggest, inspired by Robert Brandom, that to 'know' something is to take responsibility for a judgment. We are always already within the space of reasons. If you disagree, please make a case. (And there's the rub. )

It is true that I find it impossible to question the ontological existence of a mind-independent world....
Otherwise I would be diagnosing myself as schizophrenic, hallucinating about things that are not really there. — RussellA

As I see it, the idea of the self always already includes the idea of the other. Your 'I' or 'self' is the bearer of responsibilities and entitlements, the 'virtual' source of deeds and claims, and the target of rewards and sanctions. It's absurd to rationally question the very framework of rationality. It's literally anti-social madness.

Berkeley's argument "the mind....is deluded to think it can and does conceive of bodies existing unthought of, or without the mind, though at the same time they are apprehended by, or exist in, itself" may be countered by common sense justifications. — RussellA

Berkeley's 'esse is percipi' principle wasn't meant in the sense of a speculative truth-apt empirical proposition, but as a grammatical norm for eliminating i) Cartesian doubt regarding the existence of the external world that inevitably arises when the world is thought of as being only knowable indirectly via intermediate mental representations and ii) Lockean doubt regarding the existence of either primary or secondary qualities, that arises when the 'subjective' content of perception is believed to be ontologically separate from 'objective' mathematical structure.

It is ironic that Berkeley's 'realist' critics misunderstand him by projecting their own deeply entrenched representationalism onto his remarks and then attributing to him the corollaries of their own positions.

Understood correctly, Berkeley was a defender of common-sense who cannot be interpreted as saying that the world is a 'figment of the imagination', unless the concept of 'imagination' is generalised to such an extent that it includes the content of all involuntary perceptions, to the point that the phrase "figment of the imagination" no longer says anything.

There's also the problematic issue of 'private knowledge' — igjugarjuk

Private knowledge of representations
I observe an object in the world and have subjective knowledge of the colour red in my mind. As the object in fact emitted light of a wavelength of 700nm, my perception of the colour red can only be a representation of a wavelength of 700nm. My perception of red is private, in that no-one else will be able to perceive what I perceived. It is private knowledge and will forever remain private knowledge. And yet there is a public word "red" that allows me to discuss publicly what I have privately perceived.

My understanding of how this is achieved I wrote here

Universals are thoughts — RussellA

Inferentialism and Representationalism are both required within language
For Brandom, the meaning of a sentence comes from its relationship with other sentences using inferential logic. This is along the lines of Wittgenstein's "meaning is use" in Philosophical Investigations.

As I see it, both Inferentialism and Representationalism are required within language.
Inferentialism is about coherence within a given language, and Representationalism is about correspondence between the language and the world. Inferentialism allows new ideas to be discovered by finding new relationships between existing ideas and Representationalism allows new ideas to be discovered in the world.

Reason and judgement are needed by both Inferentialism and Representationalism, whether the inferential logic of Inferentialism or the discovering of concepts in the constant conjunction of events in the world. As reason and judgement are attributes of the mind, they can only be the responsibility of the individual making that reasoning and judgement.

Inferentialism uses inferential logic within language itself, but as language exists publicly within the world, there is no difference in the way in which we perceive objects in the world within Representationalism and language as an object in the world within Inferentialism.

IE, our knowledge is always of representations of objects in the world, whether the subjective colour red in the mind representing the object 700nm in the world or the subjective concept red in the mind representing the public word-object red in the world.

It's absurd to rationally question the very framework of rationality — igjugarjuk

I agree

The mind cannot change without a corresponding change in the brain

I am arguing from a position of Reductive Physicalism rather than Non-Reductive Physicalism, where mental states are nothing over and above physical states, and are reducible to physical states. For every actually instantiated property F, there is some physical property G such that F=G.
The mind exists within the brain. The brain is a physical structure and is the framework. The mind is the content. What is in the mind corresponds to what is in the brain. What is expressed in the mind must be in some way be expressed in the brain, in that the mind doesn't have a soul outside of time and space allowing it to act independently of the brain. The mind cannot change without a corresponding change in the brain.

The Self cannot inspect itself

Hume’s denial that there is an inner perception of the self as the owner of experience is one that is echoed in Kant’s discussion in both the Transcendental Deduction and the Paralogisms, where he writes that there is no intuition of the self “through which it is given as object”

On the nature of self-awareness, for example, in an unpublished manuscript Schopenhauer concurs with Kant, asserting that, “that the subject should become an object for itself is the most monstrous contradiction ever thought of”

The same can be said of the Wittgenstein of the Tractatus, who famously likens the self to the eye which sees but does not see itself.

Change cannot be spontaneous

A physical structure can be changed by something exterior but cannot spontaneously change itself, in that a snooker ball can start to move when hit by a snooker cue, but a snooker ball at rest cannot spontaneously start to move.

The brain is a set of physical parts. Each part may be changed by something exterior to the part, but each part cannot spontaneously change itself.

Even if there is nothing external acting on the brain, the brain may change because of the interaction between the parts that make it up. The brain as a whole is changed by its parts, not by the set of parts acting as a whole. The brain as a whole cannot be changed by the brain as a whole, meaning that the brain cannot change itself.

A framework consisting of a set of parts may change by the interaction between its parts, but not by the set of parts as a whole, ie, a framework cannot change itself.

IE, our rationality, our self, is not the content of the framework of the brain. Our rationality, our self, is the framework of the brain. As a framework cannot question itself, as you say, "It's absurd to rationally question the very framework of rationality."