we start to have a situation where we just can’t relate to that person — Richard B

One metric that language fails to immaculately communicate is intensity. Let’s take a negative emotion like fear. We can say that an event was mildly disconcerting or extremely petrifying. But there’s a range of fear situated between all of those descriptions. We could try to quantify the fear by saying we were 80% afraid though we’d then lose the tone and fluency of our intended statement.

We use perspective to infer distance. That distance is the extent of empty space between you and the object. Therefore we can use perspective to infer empty space in general.

One could say that the curved retina demagnifies the object to create perspective. This would be instead of the expanding sphere of decreasing light intensity coming from an object having a magnifying effect on those closest.

“If you look at a photograph of people, houses and trees, you do not feel the lack of the third dimension in it . We should not find it easy to describe a photograph as a collection of color patches on a flat surface; but what we see in a stereoscope looks three- dimensional in a different way.

((It is anything but a matter of course that we see ‘three-dimensionally’ with two eyes. If the two visual images are amalgamated, we might expect a blurred one as a result)” Wittgenstein, PI

“The colour of the visual impression corresponds to the colour of the object (this blotting paper looks ponk to me, and is pink) - the shape of the visual impression to the shape of the object (it looks rectangular to me , and is rectangular) but what I perceive in the dawning of an aspect is not a property of the object, but an internal relation between it and other objects.” Wittgenstein, PI

https://www.bbc.com/future/article/20150925-blindsight-the-strangest-form-of-consciousness
“Some people who have lost their vision find a “second sight” taking over their eyes – an uncanny, subconscious sense that sheds light into the hidden depths of the human mind... What causes the conscious and unconscious to decouple so spectacularly?”

Could it be that they are in fact consciously seeing the object but are then instantly forgetting it like a dream? That way they’d have a subconscious intuition of where it’s located.

I’m short sighted so when I take off my glasses the distant objects look blurry. I don’t notice a big metaphysical change though. I tend to wear my glasses all the time. Maybe if I walked around without my glasses more often I’d appreciate the wave side of wave-particle duality!

One more criterion for comparing anti-realism to materialism is the phenomena it might predict. We all know the amazing mathematical predictions from deterministic, classical physics. Perhaps a benefit from an anti-realist attitude is to predict the behaviour of fellow people. If other people’s perception have non-real components then someone could use their own spiritual perception to relate to them better.

An antirealist is "a person who denies the existence of an objective reality". — Michael McMahon

I am among the ones who believe that there is no objective reality. Yet, I consider myself a realist, in the sense of a person who accepts a situation as it is and is prepared to deal with it accordingly ...

I consider myself a realist, i.e. a person who accepts a situation as it is and is prepared to deal with it accordingly. — Alkis Piskas

I believe an anti-realist can also be pragmatic. Our power is limited in this world whether it’s real or not. The subconscious mind has involuntary parts that I can’t change. I’m unable to volitionally swap the colour brown and green in my vision because it’s not under my control. Colour might be internal but that doesn’t mean I can alter it. The laws of physics are impartial arbiters so we can’t interfere with someone else’s consciousness in either a real or non-real world without affecting their physical brain. Our communication is mediated by physical matter and not mental signals.

"anti-realism" literally indicates the opposite of "realist", i.e. one who is idealist, romantic and such stuff — Alkis Piskas

Anti-realist isn’t the same as anti-realistic! It doesn’t dispute the existence of a shared space. What anti-realism implies is that our perception uses some mechanisms that might not be materialistic in nature. However there are other procedures the mind uses that are materially reductionistic. For instance the shapes of objects are reductionistic.

Using labels such as "anti-realist" only limits subjects, situations, ideas and so on. — Alkis Piskas

I feel when the hard problem of consciousness still defies scientific explanation after hundreds of years then all options should be scrutinised. Let’s remember the goal is not necessarily to find only a materialistic explanation but at least an intuitive understanding of how consciousness affects the physical world. An example of this is where a hypothetical proof of consciousness being fundamentally untraceable would also ironically count as a solution to the hard problem.

By saying that "the world is real" I assume you mean that "the physical universe exists", right? But it does not exist because other people can percieve it. — Alkis Piskas

Were the world completely physical and yourself the only conscious being then that wouldn’t be a real world as such. If someone else could somehow witness my dreams then the dream would actually be real in the sense that there’d be shared agreement on its content. Therefore other conscious agents besides ourselves are necessary to validate our world.

And this is exactly what reality is all about: How one perceives the physical universe. — Alkis Piskas

Yes sense perception is needed to find our way around the world we live in. Although self-awareness is usually part of our definition of reality. Thus the mental universe also holds some importance.

I am among the ones who believe that there is no objective reality. — Alkis Piskas

If a tree falls in a forest and there’s no one to see it then it’s location is unknown to all of us. If one person is there to witness it, it remains a mystery to the rest of us until they choose to tell us. Thus one conscious observer doesn’t instantaneously remove the randomness from your own perception. From a soldier’s point of view a bullet aimed at them is randomly located until they get hit or hear it whizzing by. If your consciousness is in a separate location to mine then maybe an external object hidden in your vision truly is in a random superposition. We could perhaps combine entanglement with the problem of other minds. If each of our minds occupy unique, non-interacting streams of consciousness experience then maybe we can’t agree on an absolute nanosecond timeline of events.


https://www.symmetrymagazine.org/article/the-quest-to-test-quantum-entanglement
I’m a mere lay person but the situation goes from pure randomness to absolute determinism with only one observation. Maybe the person receiving the second predetermined particle is conscious at a different time to the sender.

You are right about being pragmatic. I also agree with other things you say.
BTW, I have removed the rest of my comment because I consider it actually "off-topic". Sorry about that!

“Common to many science fiction stories, the brain in the vat outlines a scenario in which a mad scientist, machine, or other entity might remove a person's brain from the body, suspend it in a vat of life-sustaining liquid, and connect its neurons by wires to a supercomputer which would provide it with electrical impulses identical to those the brain normally receives.”

If perception is part of our consciousness under panpsychist models then it follows that removing all perception will stop consciousness. Therefore the brain couldn’t be computationally alive on its own without the body and a sensory medium like touch or hearing. Patients in locked-in syndrome still have some neuronal senses and meta-senses working such as vision and hearing the sound of their inner voice. The brain in the vat conundrum is not only important for understanding whether our reality is real but also the connection between mind and body should the body be fictitiously detached from the brain and spinal cord without somehow causing death.

https://courses.lumenlearning.com/wmopen-psychology/chapter/reading-touch-and-pain/

Intricate touch receptors wouldn’t be easy to imitate through electrical wires to the brain in a vat.

https://eschooltoday.com/learn/the-sense-of-touch-2/

Could are sensory receptors themselves have elements of our consciousness?

“It’s the most overused of horror clichés: A villain is stabbed or shot repeatedly, blown up, burnt, melted, nuked, thrown off a building — you name it — and somehow still manages to come back for one final shock, usually just as a movie is about to end. But when done properly, the “Not Dead Yet!” scare can be a glorious thing.”
https://www.google.ie/amp/s/www.vulture.com/amp/2018/11/the-25-greatest-not-dead-yet-scares-in-movie-history.html

Why have a brain in a vat when you can have a brainless body? Ever had a dream where a character gets impaled in a sword fight and they continue on nonchalantly?

Besides even if we could artificially simulate our senses you’d still have to instantaneously rewire the brain with electrodes to prevent a deadly gap in awareness.

I believe an anti-realist can also be pragmatic. Our power is limited in this world whether it’s real or not. — Michael McMahon

This is a fascinating claim, "Our power is limited in this world whether it's real or not". From an anti-realist perspective, this claim does not make much sense. If there is not "a world out there", what sense can we make of the idea that we can have shared agreement about this world's content?

But let us assume for a moment that there is a world we conceptualize together, what is being articulated when we question whether it is "real or not"? This distinction has no meaning when applied to the world as a whole. Think how we come to use this concept of "real". Usually after contrasting two different situations or objects, we find it useful to make a distinction in calling it "real" or "not real". In the case of the "world as a whole", what am I contrasting? I have no experienced of two different worlds, there is just one. What about looking at it it from a scientific perspective? How would a scientist go about determining if this world is "real" or "not real"? Or, take the hypothesis that this "world is not real", what experience(s) could falsify such an idea?

What if I said that the world is one of three possibilities: real, not real, and null. You may ask, "what is null?" and I replied, "the world is exactly as we perceived it if it was real or not, but it is neither, it is null." Have I really described three possibilities here? Maybe there is not three possibilities, but only one actual.

How would a scientist go about determining if this world is "real" or "not real"? — Richard B

The mind is more arbitrary and whimsical in nature than the physical structures we observe. What would a random universe look like? For starters we can’t change the past and so the passage of time means every random decision is conditional on previous random outcomes; thereby reducing latent randomness. In that way our “power is limited”. Evolution says the human body is random yet we are never surprised by looking at fellow humans because we’ve grown accustomed to our physiology. We think donkeys are funny while a donkey probably thinks we look weirdly amusing with our flat faces and short noses! A person from a different planet would think our gravity is utterly bizarre though we’re so familiar with the way objects fall down that everything seems ordinary. For all we know the big bang was entirely random in the laws of physics it developed and the subsequent early universe may have become progressively less probabilistic.

“The probability that any given person has a cough on any given day may be only 5%. But if we know or assume that the person is sick, then they are much more likely to be coughing. For example, the conditional probability that someone unwell is coughing might be 75%, in which case we would have that P(Cough) = 5% and P(Cough|Sick) = 75%.
Conditional probability is one of the most important and fundamental concepts in probability theory.”

How random would we view our place in the world if we could see planets with the naked eye?

I wonder whether the guy who looks after the brains in vats is ever tempted to let one of them in on the secret. I think about that guy sometimes. Lonely job - all those brains and nobody to talk to.

The mind is more arbitrary and whimsical in nature than the physical structures we observe. — Michael McMahon

I guess the mind is not “arbitrary and whimsical in nature” when we determine the physical structures we observed so we can make the claim “the mind is more arbitrary and whimsical in nature than the physical structures we observe.”

take the hypothesis that this "world is not real", what experience(s) could falsify such an idea? — Richard B

Perfect circles don’t exist in nature and pi has an infinite number of digits. So when you rotate around and move forward in a certain direction, we don’t ever know with perfect accuracy what that direction is. We see with the 3-body problem that movement can be chaotic between multiple connected objects. Fractal and chaos theory tells us the object’s constituent particles might be impossibly complex to understand reductively. A material object is physical but sometimes it’s not just chaotic but multitudes of chaos built on top of yet more chaos. Maybe it’s not technically random but neither is it predictable or deterministic. Thus it’s more open-ended and subjective: should we interpret it closer to being material or random?

Perfect circles don’t exist in nature and pi has an infinite number of digits. So when you rotate around and move forward in a certain direction, we don’t ever know with perfect accuracy what that direction is. — Michael McMahon

So, if I understand this correctly, if we can’t prove without “perfect” accuracy the outcome of some predicted event, this is evidence the world is not real. This is an odd conclusion. For example, I shoot a cannon ball and predict with current scientific principles that it should travel 15.01 feet. But when I measure it, it is only 15.00 feet. So, I must conclude the world is not real? Maybe we should consider other possibilities, measurement error, technology limitations, revision to principles, etc. Historically speaking, we have become more accurate with our scientific prediction, by Special and General relativity. So does this means the world in becoming more real? No, we can just make better predictions.

if we can’t prove without “perfect” accuracy the outcome of some predicted event, this is evidence the world is not real. This is an odd conclusion. — Richard B

I watched a YouTube philosophy video that mentions a “frustrator”. It’s about trying to predict whether someone will press one of two buttons when they are alerted to your prediction in advance. It alleged that the person could change tack even when you know every law of physics about the situation. A real life version is when Libet could predict your decision from your brain waves a half-second before you consciously decided to move. There’s debate about a veto power in that instance. Let it be known that if anyone comes to me and makes a secret prediction from my neurons about where I’ll be in an hour and afterwards meeting up to see that they were right, then this would persuade me that I’m a wholly physical being. The catch is predicting that I’ll be in the sweet shop doesn’t count!

Remember our volitional muscles are always partially active through muscle tone. Maybe when we are choosing which arm to move, one of them will automatically tense up to permit motion. So the action of subconsciously increasing tone makes it easier to move the selected arm over the relaxed muscles on the opposite arm. Perhaps this biases our decision to pick one arm over the other without actually having compelled us.

“When people talk about the possibility of foreknowledge of the future they always forget the fact of the prediction of one’s own voluntary movements.”

Wittgenstein, PI, 628

“In the laboratory, when subjected to an electric current, for example, someone says with his eyes shut “I am moving my arm up and down” though his arm is not moving. “So,” we say, “he has the special feeling of making that movement.” Move your arm to and fro with your eyes shut. And now try, while you do so, to tell yourself that your arm is staying still and that you are only having certain queer feelings in your muscles and joints!”

Wittgenstein, PI, 624

when subjected to an electric current, for example, someone says with his eyes shut “I am moving my arm up and down” though his arm is not moving — Richard B

In a dream we often have a semblance of a body even though we often don’t take any notice it. So if you were swimming in a dream then maybe you’re right and it’s just an electric current tingling our senses to simulate motion while our actual bodies are stationary. Could these motor currents be used to change dreams? For instance would mimicking uphill walking change my dream narrative from whatever it was to a different memory where I was climbing or trekking?

When people talk about the possibility of foreknowledge of the future they always forget the fact of the prediction of one’s own voluntary movements. — Richard B

Perhaps while we’re asleep we first think of a cool sequence of events and then forget the order so that we can visually re-enact it. Then our subconscious would have “foreknowledge” of what will happen to us in a dream.

“Perhaps while we’re asleep we first think of a cool sequence of events and then forget the order so that we can visually re-enact it. Then our subconscious would have “foreknowledge” of what will happen to us in a dream.”

No way ever to verify this and there never will be.

If the visual world were 2D then it’d be like our mind teleports forward whenever we walk around. In this example the mind would be stationary in the brain and so wherever you travel your consciousness would still be in the same location throughout the day. You wouldn’t actually be traversing any 3D space so to speak. It’d feel like you were gliding through centimetres of depth.

If the mental sphere took up space then it would create a double occupancy problem with physical space unless it were always a millisecond ahead or behind physical time.