Yes, but I in turn can expect that philosophers one hasn't read won't be rejected. — Thorongil

I'm familiar with Berkeley's main arguments and what people have said about his using God, which is similar to what Descartes did. I guess you could claim that Descartes had some other reason than needing to be saved from his skeptical exercise.

Or you could just give me a brief summary of Berkeley's arguments for God.

Well, Schopenhauer regarded Berkeley's idealism as more or less capable of standing on its own, while dispensing with God. — Thorongil

No God, no tree in the quad!

You can dispense with God, but subjective idealism loses the world when we're not looking, which Berkeley was concerned about.

You seem intent on making me do your work for you. My comment was an attempt to persuade you to go read Berkeley himself and examine his arguments, as I myself don't have the time, or really the interest, to do so at present. I just don't recall that God is "invoked" or assumed to exist, as you suggest. — Thorongil

This is a discussion forum. You can't expect others to go read material in the middle of a discussion.

Right, that's why I said, in the last sentence you neglected to quote, "They disagree about how it is supplied and how it ought to be described." — Thorongil

No, that's not the point. Direct realists disagree about the nature of experience itself. That's crucially important for making the direct realist case.

Are you saying you reject a position you haven't actually read anything about? — Thorongil

Fine, enlighten me. What was Berkeley's argument for God's existence?

In any case, I suppose I would be of the opinion that the fault line with respect to experience is not as deep as both sides like to make it out to be. The primary reason for this, again, is that neither side objects to the existence of the content of experience. — Thorongil

But they do disagree fundamentally about what an experience is. For direct realists, perception is awareness of external objects, and not anything more. So they would disagree that perception involves any sort of representation or idea in the mind. As such, perception differs fundamentally from dreams or imagination. Where hallucination fits in that is debatable.

So whether or not we can square a circle isn't open to empirical investigation? Then how do we determine that we can't? — Michael

I think the argument is that in order for the simulation to make a circle non-squarable when we try to square it, it would have to compute the transcendental number PI, or we would be able to accomplish the task.

Berkeley, for one, does not do that, though. He provides arguments. — Thorongil

What sort of arguments does he provide for God's existence? That God is necessary for the tree to remain in the quad unperceived by us? How is that fundamentally different from saying the unperceived tree must exist?

It wouldn't have to generate the whole universe, though. It would only have to generate the things that you will actually see. — Michael

But it does have to potentially generate anything you or anyone could actually see, hear, etc.

That's fascinating if it's correct. I'm a bit skeptical that math can be used to prove something metaphysical, but if it can, that's very deep stuff.

I've watched NGE and Deep Space Nine. I still can't imagine a holodeck the size of the universe. — fdrake

If you ran a planet-sized holodeck, would we be able to know it wasn't actually the size of the universe? We could think we were sending a probe off into deep space, and it's just the program making it look that way. Even in a room-sized holodeck, they're somehow able to move around quite a bit as if they weren't constrained to a room.

I literally can't imagine what that would be like in any coherent way. I suppose these arguments aren't very good at convincing the unimaginative. — fdrake

Have you watched any of The Next Generation or Voyager? It's not uncommon for some of the crew to spin up a holodeck program that's as sensory rich as the real world, and there be a malfunction where they're trapped in the program and can't exit.

In one, a simulated character who had become aware made a simulation of the entire ship to fool the crew members into thinking they had exited the holodeck.

The speed we think and act probably puts some bounds on their informational content. But the speed alone tells us nothing about how hard it would be to simulate human experience, or to provide real-time equivalent stimulations to a brain (assuming the brain can indeed be stimulated to produce these things without sensorimotor constraints and the nervous system at large... which is unlikely). — fdrake

That might be so for BIVs, but it won't be so for holodecks, since holodecks feed our sensory organs instead of our brains. Imagine the ST universe where a whole civilization lives inside a large holodeck. And that leads to another possible answer to the Fermi Paradox.

All advanced civilizations end up inside simulations, because they're far more appealing than exploring space.

The simulation only needs to simulate what we see. What we see is the device and its human-readable output. — Michael

The computer needs to be able to compute the result of any experiment we might think to devise in a convincing fashion. That goes way beyond simply fooling the human visual system.

The human technology is part of the simulation, too. I'm not sure what you mean about fooling the math. — Michael

The fact that we can compute PI to huge numbers of places means the simulation has to be able to do that. And that we can devise physics experiments that can measure the amount of time it takes light to cross the length of an atom means the simulation has to be able to accommodate that.

That requires way, way more compute power than fooling the naked eye.

So the idea is replace all experiences with exactly equivalent substitutes which come solely from stimulating the brain?

Presumably this is automated to be real time. — fdrake

Well, the brain isn't very fast compared to computers. It takes a quarter of a second or so to think a thought or recognize an object. Responding to a startling sound is much faster (50 milliseconds), but it's still slow compared to computers which can operate on nanosecond time frames.

Although I wonder if your floating point number example even works for the computer simulation. The precision only needs to be high enough to fool the naked human eye. — Michael

No, it needs to be high enough to fool human technology and math. That's why some people have speculated that physics might be able to show we're in a simulation.

Is there a distinction between something existing in God and existing in God's mind? Is God a mind or does he have a mind. — Janus

Invoking God to make idealism work because of epistemological concerns over unperceived objects is hugely inconsistent.

I didn't mean "reason" in these sense of "purpose". I meant it in the sense of "cause"/"explanation". — Michael

Right, okay then no disagreement here. I think Banno was talking about meaning/purpose, not causality.

I believe the hypothesis trades on logical possibility, not physical possibility. — Michael

Right, but it the hypothesis also needs to make sense. So you could argue that realists cannot coherently say our world is a simulation if building such a simulation in our world is impossible, because we have no way to refer to the states of affairs of the real world in which in our simulation lives.

I think Thorongil meant to "the more important question is not what objects are, but why they exist." We are not responsible for the reason of a thing's existence (excluding the obvious man-made stuff). — Michael

Oh well, why ask why? What reason do we have to suppose things have a reason for existing? We can explain the mechanics for how they came to exist (to a point), but not give a reason in terms of purpose.

I don't think even that would work, as it could be that the "real" world operates according to different physical laws, and the ones we're familiar with are only the laws of our simulation. — Michael

Like maybe in the real world P=NP, but not our simulation?

But it seems like if you could show that it's impossible to construct a simulation in our world, then the basis for the simulation argument is undermined (because what do you mean by our world being simulated?). However, that sounds related to Putnam's argument against being able to make a radically skeptical realist assertion.

I don't think so. — Thorongil

How could the why not be up to us? Are you in personal contact with God or aliens? What sort of BS have they been feeding you?

I suppose if you could show that we can't be brains in a vat even if metaphysical realism is the case then you can argue that realism doesn't entail radical skepticism, and so refute Putnam's argument. — Michael

Maybe so, but t's hard to see how metaphysical realism doesn't entail the possibility of some form of radical skepticism, even though I am a realist.

Even if BIVs aren't tenable, a Matrix, Star Trek holodeck or Boltzmann Brain scenario might be. You'd have to show that such a simulation isn't physically possible, and everything I've read leads me to believe that it is possible to compute a convingly realistic world. And if you're born into that world, you wouldn't know what was unrealistic anyway (relative to the actual physical world).

One possible answer to the Fermi Paradox is that advanced aliens are feeding us a simulated universe that looks empty. In that case, we'd only be wrong about the wider universe, not matters inside the solar system (extra solar light would be simulated to fool us).

hat classic scientific theories assume that things exist unperceived is a kind of bias of those theories. It isn't needed to make sense of them, so far as I can tell. It just requires imagination and the willingness to entertain views which are different to what we ordinarily accept. — PossibleAaran

Not sure how you can accept chemistry as scientifically valid without conceding the existence of the atomic world which makes the periodic table what it is. Same with the germ theory of disease, cell biology or neuroscience.

Sure, we have equipment that can make those things perceivable to us, but most of the time atoms, microbes and cells are unperceived. The molecules science says you are made might never have been perceived by anyone.

So the reason idealism is significant, is to remind us that knowledge is always conditional, dependent, and in some sense subjective. Not in the sense of there being simply no objective truth, but that there is no ultimately objective truth. — Wayfarer

But this conflates epistemology with ontology. Just because there is a process by which we come to know about the world doesn't mean the world is constituted of that process.

We can analogize this to modern astronomy where sophisticated telescopes feed data to software that produces results for astronomers to analyze. There is a process in constructing knowledge of the cosmos.

But that doesn't mean the cosmos is therefore constructed by telescopes and software! It's a fallacious move to make. This is where Stove's worst argument gets it right.

Again, this is the core problem with Idealism and phenomenalism as I see it: they want to keep their cake and eat it. They want to call what's happening in the present moment "experience", "perception", "observation", etc., etc., but they want to retain universal doubt. But if you're universally doubting, then you can't call what's happening right now "perception", "experience", "observation" etc in the first place. But then as soon as you accept those terms, you implicitly accept the physical backstory, so there's no place for universal doubt any more. — gurugeorge

That's a really excellent critique. It undermines much of the bite of the hardcore idealist means of arguing where it's just one experience followed by another and nothing can be said of what happens in between.

So, the belief that the coffee exists unperceived isn't one that can be reliably established by any method at all. It is like the belief that there is a unicorn on mars. — PossibleAaran

It isn't like a belief in a unicorn on mars at all. We do have good reasons for thinking objects exist unperceived:

1. They're still around when we do perceive them again.
2. They can undergo change in our absence.
3. They can influence things we do perceive.
4. The perceived world is dependant on the unperceived for being the way it is.
5. We have no reason to suppose that things stop existing when we're not around.

A unicorn on mars doesn't fit any of that. It's like saying we have no reason to think unperceived paper doesn't turn into a unicorn or teleport itself to Mars. Why must it not exist? Why not anything fanciful? We're not perceiving the paper, so it could be anything or anywhere in addition to not existing, logically speaking.

Why is your doubt fixated on non-existence instead of any of an infinite number of unperceived scenarios?

Yes; doubt requires justification, too. — Banno

Maybe you can bring that up on the unperceived things not existing thread? OP is looking for a reason not to doubt. He mentions the idealist Stace who argued that there is no reason for thinking that unperceived objects and events exist.

Indeed, habit, as Hume himself says; but it is a leap that reason cannot justify. — unenlightened

Why is reason defined as deductive logic? Seems that animals and humans rely heavily on inductive reasoning. Deductive is something we came up with rather recently, but our ancestors didn't use it to survive, communicate and utilize tools, etc.

What ground do you have for supposing that the sun will not rise tomorrow? — Banno

Nothing and we have no grounds for expecting things to happen for no reason, particularly when it comes to large, complex objects like the sun.

It's like asking how do we know the sun won't turn into a giant teapot tomorrow. We can't prove that it won't deductively, but we have nothing that says stars have a means of turning into teapots.

Mathematical equations are meaningless symbolics until observations are substituted for variables. — Rich

That's why I said the world could be depicted by math. E=MC^2 means that the amount of energy in certain amount of mass is equal to that mass times the speed of light squared. That applies to any matter/energy conversion across space and time.

There is always some Mind (perspective) involved when observing and trying to understand or predict behavior(habits) in the universe. — Rich

Yes, but you're conflating how we know and represent things with the world itself. Are stars and galaxies dependent on telescopes and the software that processes those images? Of course not. That's just how modern astronomy gathers astronomical data.

Epistemology is not ontology.

I can see that the paper existed when the camera took its picture, but does the paper exist now? The camera is nothing more than an extension of the times at which I can view the paper; it cannot show that the paper exists unviewed tout court — PossibleAaran

What if you had a camera take a picture of the paper every nanosecond while it's in the drawer, and send that image to be processed by some software elsewhere. If the software sees that the image is a paper, it wires a cent to your bank account.

You step out of the room and check your account a minute later and notice that it's gone up by millions of dollars. The paper, drawer, camera and software doing paper detection and money wiring are all unperceived, but your bank account gains a lot of money very quickly, which if you calculated the time it took for the image to be taken, sent, processed and your count accredited would come out to having a picture taken every nanosecond by that camera with that software on the server it runs on at that time with your internet connection (the images would be buffered as they arrived, waiting for the software to check them).

Would that not establish the existence of the unperceived paper, at least every nanosecond (or however many nanoseconds got turned into cents)?

The point is that the perceived world is influenced by the unperceived world. You can't just say the rest of the world only exists when perceived given the way the world hangs together. The reason being that the perceived part of the world is being influenced by the unperceived world in countless ways.

You're not familiar with cosmology, are you? — Metaphysician Undercover

I'm familiar with the speed of light being a constant against which measurements of length and time are made across different inertial frames. Note the taking into account different observers making measurements.

I'm also aware that GR accounts for gravity across the cosmos and throughout time.

e cannot produce a mathematical model of the universe which is independent from perspective. This is one of the key things that special relativity demonstrates to us. — Metaphysician Undercover

Pretty sure you're wrong about this.

We already agreed that the Idealist can posit (a) a car hurtling towards him when he sees it, and (b) a car hitting him in the back when he feels it. He need not postulate a car which exists in the interim, when he is not seeing or feeling a car at all, nor need he postulate that these three are 'the same' car. — PossibleAaran

But he might not feel anything as well. Experience just ends.

Why is there the concretely, fundamentally, objectively existent world that you believe in? — Michael Ossipoff

Ask a cosmologist. In general, why anything exists is a question everyone has a problem answering.

As I've said, I can't prove that the Materialist's concretely, fundamentally, objectively existent world doesn't superfluously exist, as an unnecessary brute-fact, an unverifiable and unfalsifiable proposition, along side of, and duplicating the events and relations of, the complex system of inter-referring abstract if-then facts about hypotheticals that i've been referring to. — Michael Ossipoff

And I wouldn't agree with that depiction of materialism.

Without a temporal perspective there is no such thing as the way that the world is. That's why it's a senseless questi, on to ask about the way that the world would be without an observer. Without an observer there is no such thing as the way that the world is. — Metaphysician Undercover

And I explained how I disagree with that, given that we can depict the world mathematically without a perspective, and given that our lack of a ability to picture a perspectiveless world does not necessitate the world can't be that way.

Does it make sense to think that a brain can represent to itself the criteria of its own existence? — sime

Sure, why not? The brain recognizes that it has a limited lifespan. It sees that it's made of the same biological stuff that everything else is, which means it will die.

All i mean to say is that if subjective idealists are understood to be verificationists in the strongest possible sense, then it makes no sense for them to speak of an absence of experience when it comes to their own experience. — sime

Would such verificationism also commit one to not being able to speak of past experiences except as memories now, or future experiences except as anticipation now?

IOW, all that could be known to exist is the solipsist's perception right now.