At first sight, consciousness seems redundant. Seemingly a person or animal could react to the world 'normally', without the intervening step of internal consciousness. Kind of like a machine following an algorithm, or the Behaviourists’ black-box model of stimulus-in / response-out. But dead inside, like a Zombie. This notion raises the question of "why do we need consciousness?" — Kym

Wouldn't this suggest that the bottom-up model is missing something?

An illusion? Well, a convenient fiction at least. It turns out the these is no distinct redness in the material world. There is in fact a seemless array of available wavelengths across very wide spectrum (most of which is quite invisible to us but still real). We perceive a distinct redness after our red colour cones are triggered by a certain range wavelengths. — Kym

There is a problem with taking this approach. If red is an illusion or convenient fiction, then what makes light waves any more real?

We've come to explain vision in terms of photons bouncing off objects into our eyes because we perceive color in the first place, and then did a bunch of experiments to explore the phenomenon and came up with a physical theory as a result.

Empiricism is undergirded by subjectivity. If you make the subjective an illusion, then there goes the basis for knowledge about the physical world.

the problem has always been one of legitimacy. In allowing arguments from racists, say, to be aired, what is conferred upon them is legitimacy: one admits it as an option to be considered at all in the first place — StreetlightX

Mill would have strongly disagreed with you. In his day, the equivalent was obscenity or atheism as far as what was deemed unacceptable by society at large. That's the danger. Most of us will agree that racism is wrong, but if we give society the power to deny that speech, then what speech will be denied tomorrow?

It's all good when we agree with the speech being denied, but someone else gets into power or society changes their mind and we might no longer agree. It could be our speech that's being prohibited. That's why the US is so hardcore on free speech, and the ACLU will bend over backwards to defend the most outrageous speech.

Mill thought it was important for us always to have to defend our ideas against all-comers. It's important for society's growth to have to hash out dissenting ideas.

I expect Kant would have been entirely comfortable with the notion that our in-built mechanism for arranging information is an approximation to a paradigm whose differences are only visible at scales that are beyond ordinary human experience. — andrewk

I highlighted the interesting part, because what does it mean for Kant for something to be beyond ordinary human experience, particularly in context of:

we process raw inputs within a framework of three space dimensions and one time dimension. — andrewk

Also, modern physics has entertained higher dimensional space and colliding branes, along with multiple universes. I wonder if those concepts could fit into the transcendental aesthetic since they're so far beyond the normal framework of space/time.

It is not going to destroy the fabric of society. — Maw

What is the fabric of society that everyone's so worried about destroying?

Yes, it mind vibrating. — Rich

So the universe is made of vibrating mind instead of those tiny higher dimensional strings of energy?

That said, the world's total fertility rate has been declining for some time and will continue to decline, so the world's population is not expected to continue increasing at an exponential rate for very much longer. — Thorongil

We're supposed to top out around 10 billion at mid century, so it becomes a question of whether Earth can support 10 billion for the second half of the century.

If we were much more efficient and more focused on sustainable technologies, then I think the answer would be yes. But so far, we've been very wasteful and uneven in resource distribution. Maybe that will change in the future out of necessity.

The skeptic' is a bogeyman in philosophy discussions, nothing more. — fdrake

Well, there is Nick Bostrom's simulation argument. Sounds like he and quite a few others took it somewhat seriously.

You had Elon Musk asking physicists to find a way out of the simulation! Maybe they told him to shoot a Tesla into space. That would break the simulation for sure.

The skeptical challenge remains the same in both scenarios. — Moliere

So the skeptic claims that we can't know about the external world because it's possible to doubt it?

That's a really high standard for knowledge. There are rare psychological cases were someone comes to believe their family has been replaced by imposters. And how can you be certain that doppelgangers didn't replace the people you know while you were asleep last night?

On the skeptic's standard for knowledge, I can't know the people I claim to know.

Conditional: brain in vats and memory editing. Should be believed? Nah. Kind of thing people can get therapy for. — fdrake

Maybe the evil demon created us as BIVs 5 minutes ago with false memories of a past. But the evil demon itself is a simulation, so he has to trick us into thinking we know about transcendental numbers.

Listened to a Science Friday podcast recently where they had physicists on answering questions about what they're excited about. This one physicist said we're just at the beginning of learning about the nature of space that will take us a thousand years.

Yes. But as long as they are understood to be idealizations and not actualized, then I don't see the problem. As an analogy, we have a concept of infinity. It doesn't follow that the universe is necessarily infinite. Similarly for the simulation. — Andrew M

You don't think it would be a problem for the simulation computing our coming up with those idealizations?

Here's an interesting question. Could a simulation learn about the halting problem?

I have no idea how that addresses my point, which is that given our axioms and definitions, that Pi is irrational deductively follows. Unless you want to say that a simulated world can defy logic, the same is true in a simulated world. — Michael

Just pointing out that Sagan though the exact value of PI could be determined by the shape of space one exists in. It's not exactly the same, but it goes to the notion that PI's value might be calculated to be different depending on the world one lives in.

Given the same axioms and definitions, whatever deductively follows in the real world will deductively follow in a simulated world. — Michael

At the end of Carl Sagan's Contact book, a human computer finds a binary representation of a circle inside PI created by aliens who shaped our universe in a way such that PI would have that value so that any sufficiently advanced race who evolved could find out they were inside a created universe.

I always wondered how the value of PI could be modified by the shape of space, but Sagan put that in his story. If it can, then that might have bearing on the value of PI computed inside a simulation.

I always thought PI had to be the same value regardless, but it seems some disagree with this.

Why would you suppose reality has a value for pi? — Andrew M

We do have a mathematical value for PI which is irrational and cannot be computed (in full). A circle's definition is determined by the full value of PI, mathematically speaking.

I think fdrake is arguing that the simulation would have to compute us coming up with irrational numbers and other things which aren't computable, such as transfinite numbers. Or the halting problem.

Didn't realize that BIV discussion would result in a debate on whether a computer can simulate squaring PI.

All that shows is that you are mistaken about what you possess being subtlety. Subtlety cannot be heavy; its character is the very opposite of heaviness. — Janus

His subtle wit was so enormous that it sucked the mood of the room into a slowly forming vortex of chuckling, collapsing into outright laughter, swallowing all seriousness in a black hole of guffaws.

1) All ideas must be perceived. — Bishop Berkeley

Question for anyone: how does Berkeley distinguish between other experiences and perception? Is my dream tree not an idea? Must ideas be public/intersubjective?

Anyway, from reading those two arguments, I think Berkeley would side with materialists over atheist subjective idealists if he was forced to choose between the two.

He seems to fundamentally agree that objects persist and have causes, both of which subjective idealists tend to deny.

In the first argument, a is interesting:

a) Our ideas of sense must have a cause — Bishop Berkeley

Because Berkeley ignores Hume's point, but many idealist love to use Hume's skepticism to undermine materialist arguments for causation.

Materialists would agree with this premise as well!

Alright, thanks. The second argument I find interesting:

1) All ideas must be perceived.

2) Sensible objects are collections of ideas.

3) Objects continue to exist even when they are not perceived by any finite minds. 4) Therefore, there is a nonfinite spirit or mind which perceives objects. — Bishop Berkeley

Materialists would agree with the bolded part. It's interesting because subjective idealists tend to disagree that objects continue to exist outside human/animal perception.

Now why would Berkeley be convinced that objects continue to exist, given that he was a subjective idealist?

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.