(due to it obeying the same physical laws as any other object in the universe), — Question

it's not an object.

The human brain is not an object, albeit a very complex one?

that the human mind is beyond the description of any formal system due to Godel's Incompleteness Theorem. — Question

I don't think that's the fundamental issue. I think it's that an objective description is abstracted away from first person experience. So the question is whether a third person description can account for first person.

Now some think if you can the mechanisms resulting in consciousness, then there's nothing more to explain. Basically, consciousness becomes brute, or beyond explanation, since explanation is third person. Or identical to those mechanisms.

So then the question becomes whether a simulation of those mechanisms results in consciousness, or whether consciousness is identical to certain biological processes. And furthermore, can we know whether other kinds of simulations would lead to non-human consciousnes? Is that a question that can be answered? Which is also related to asking questions about animal consciousness.

If we lack an explanation, then I'm not sure we can answer those sorts of questions.

The human brain is not an object, albeit a very complex one? — Question

Humans are subjects of experience. The idea that a being is simply 'information processing' is one of the basic fantasies of scientism. Really you should change your focus Question, you're just spinning wheels with this stuff.

Here's a huge problem for the CTD principle: the concept of simulation. Just what counts as a simulation is either vague/subjective or inadequate/irrelevant--the latter pair being the case if what counts as a simulation is defined purely in mathematical terms, since mathematics is a language we employ to represent ways we think about the world; mathematics certainly isn't the furniture of the world, especially not exhaustively.

In a nutshell, any x is a simulation of y only if one doesn't care about the aspects of y that are missed, glossed-over or not at all qualitatively the same. Aspects of y are necessarily missed, etc. Otherwise x wouldn't be a simulation of y, x would be identical to y, and no two numerically distinct and discernible things are identical.

since mathematics is a language we employ to represent ways we think about the world; mathematics certainly isn't the furniture of the world, especially not exhaustively. — Terrapin Station

Well, I'm a platonist. Anyhow, mathematics seems to be the language of the universe and indispensable when describing reality. Ask any scientist.

You can be a mathematical platonist, but that just means that you have an incorrect ontology of mathematics. Yes, mathematics is very useful to science, which leads a lot of scientists to have a mathematics fetish that reaches obsessive levels, where they are not only led to becoming mathematical platonists, but they start to believe that the entire world is somehow only mathematics.

....If they're called 'tegmark'

So the question is whether a third person description can account for first person. — Marchesk

It is a simple fact that the third person description cannot account for the first person, and this can easily be demonstrated from the way we analyze inanimate objects.

If we can dissect an object, we assume that the object is necessarily made of parts. When we dissect an object, to examine the parts, the original object no longer exists. Each part is now an object. So we have two very distinct perspectives, either the whole is the object, or the parts are the objects. We cannot observe the whole as the object, and the parts as the objects, at the same time, and this is born out in the nature of reference frames and relativity theory, reference frames are related by theory, not observation. However, we still say that the object consists of parts, and that the object coexists with the parts, but this is merely theory, it cannot be observed in this third person way.

In the first person, the object is the person, and the parts are within the person. Since the object is observing itself, from this perspective, it has the position necessary to observe its inner parts without dissecting itself. So the first person is the only valid perspective where we can observe an object coexisting with its parts, without annihilating the object to observe the parts, and then synthesizing the object through theory.

Whether this is true or not is highly contested by physicists to this day (Penrose, et al). — Question

The CTD-Principle is not contested, not even by Penrose. Can you spot Penrose's name on the paper that proved the CTD-Principle?

http://www.daviddeutsch.org.uk/wp-content/deutsch85.pdf

Penrose is a genius. He knows perfectly well that the known laws of physics obey the CTD-Principle and all that implies. This is why he denies that the known laws of physics operate in the human brain. He has been looking for new laws of physics that do not obey the CTD-Principle, with zero success.

All of Penrose's arguments that somehow the human brain can out Godel a computer have been debunked.

What does the principle mean by simulating a physical process? Does it mean replicate? Can a quantum computer replicate consciousness, the Big Bang, evolution, etc.? Or can it just perform some sort of representative algorithm?

I'm pretty sure that the very definition of a simulation is that it isn't the real thing. Simulated consciousness isn't consciousness, just as a simulated explosion isn't an explosion.

What does the principle mean by simulating a physical process? Does it mean replicate? Can a quantum computer replicate consciousness, the Big Bang, evolution, etc.? Or can it just perform some sort of representative algorithm?

I'm pretty sure that the very definition of a simulation is that it isn't the real thing. Simulated consciousness isn't consciousness, just as a simulated explosion isn't an explosion. — Michael

You only need a quantum computer to simulate processes involving quantum coherence, so a laptop or something similar is all that is needed to exactly simulate consciousness.

Evolution is classical, so a classical computer is all that is required. The Big-Bang would require a quantum computer to simulate exactly.

Clearly a simulation of the Big-Bang is not the real Big-Bang. A simulation of you however, would be you, just in the same way that an algorithm is the same algorithm whatever hardware is running it. You are an algorithm running on computationally universal hardware.

You're not addressing the issue of just what a simulation is. What is the definition of it, at least per the CTD principle (that was supposedly proved)?

The CTD-Principle is a discovery, that has been proved to hold for known physics. The discovery is that Reality has the surprising property of self-similarity: it is possible to simulate exactly the universe from within.

The meaning of "simulation" is defined explicitly in the paper everyone keeps ignoring:

http://www.daviddeutsch.org.uk/wp-content/deutsch85.pdf

Here's Deutsch explaining the CTD-Principle, in an accessible way, without mentioning it.

Thanks, so the definition is: "A computing machine M is capable of perfectly simulating a physical system S, under a given labelling of their inputs and outputs, if there exists a program <pi>(S) for M that renders M computationally equivalent to S under that labelling."

And he goes on to say, "In other words, <pi>(S) converts M into a ‘black box’ functionally indistinguishable from S."

So we need to know what "computationally equivalent" is defined as in order to understand the definition of "(perfect) simulation."

The closest Deutsch gets (as far as I see, at least) to defining computational equivalence in the paper are these two statements:

"Two classical deterministic computing machines are ‘computationally equivalent’ under given labellings
of their input and output states if they compute the same function under those labellings."

And then (because not all computing machines are classical deterministic computing machines):

"Two computing machines are computationally equivalent under given labellings if in any possible
experiment or sequence of experiments in which their inputs were prepared equivalently under
the input labellings, and observables corresponding to each other under the output labellings were
measured, the measured values of these observables for the two machines would be statistically indistinguishable."

And that's it. So the first problem with that is that it's only about what computational equivalence is for computing machines. Maybe he'd argue that everything is just a computing machine, but where is that argument?

What the heck would it mean for a rock, say, to be a "computing machine"? And is Deutsch arguing that that's all there is to a rock? What's the argument for that? We'd need to sort that out prior to tackling other problems these ideas have.

Maybe he'd argue that everything is just a computing machine, but where is that argument? — Terrapin Station

He is explicitly opposed to that idea. You will enjoy the video, where he explains why.

This is a quote from the text provided by tom,

For although a quantum computer has an infinite-dimensional state space, only a finite dimensional unitary transformation need be effected at every step to simulate its evolution.

How does Deutsch know this? Surely, this is a strong assumption that would require some exhaustive technical prowess in proving such a statement...

At about 2:00 Deutsch says that the existence of computation explains the unreasonable efficacy of mathematics in the natural sciences. I really don't get that. No computer or computational process could exist were it not for mathematics in the first place. Isn't it putting the cart before the horse? How come 'computation' is assigned to this kind of quasi-deistic role in Deutsch's worldview? 'There is a law of nature that the universe is computable, or that a universal computer exists'.

He is explicitly opposed to that idea. — tom

So if it's not the case in his view that everything extant is a computing machine, then there's no definition of computational equivalence in the paper that pertains to things like consciousness or rocks etc.

You only need a quantum computer to simulate processes involving quantum coherence, so a laptop or something similar is all that is needed to exactly simulate consciousness. — tom

I'm trying to understand this simulation business. I am using the critical eye of Christopher Timpson in 'Quantum Information Theory and the foundation of Quantum Mechanics'. He argues that your/Deutsch's argument is a 'simulation fallacy': that simulation is not a like for like business. Here are a couple of directly relevant paragraphs. Do you have a Deutsch rebuttal to this line of argument? It's part of a wider case, as I grasp it, that Deutsch is conflating the mathematical and the physical in 'the Turing principle' through a misunderstanding (in Timpson's view) of the original thesis.

Imagine that there is some physical process P (for example, some quantum mechanical process) which would require a certain amount of communication or computational resources to be simulated classically. Call the classical simulation using these resources S. The simulation fallacy is to assume that because it requires these classical resources to simulate P using S, there are processes going on when P occurs which are physically equivalent to (are instantiations of) the processes that are involved in the simulation S itself (although these processes may be being instantiated using different properties in P). In particular, when P is going on, the thought is that there must be, at some level, physical processes involved in P which correspond concretely to the evolution of the classical resources in the simulation S. The fallacy is to read off features of the simulation as real features of the thing simulated.
A familiar example of the simulation fallacy is provided by Deutsch’s argument that Shor’s factoring algorithm supports an Everettian view of quantum mechanics (Deutsch, 1997, p. 217). The argument is that if factoring very large numbers would require greater computational resources than are contained in the visible universe, then how could such a process be possible unless one admits the existence of a very large number of (superposed) computations in Everettian parallel universes? A computation that would require a very large amount of resources if it were to be performed classically is explained as a process which consists of a very large number of classical computations. But of course, considered as an argument, this is fallacious. The fact that a very large amount of classical computation might be required to produce the same result as a quantum computation does not entail that the quantum computation consists of a large number of parallel classical computations. — Timpson

The argument is that if factoring very large numbers would require greater computational resources than are contained in the visible universe, — Timpson

Another objection is why we'd assume that the factoring is occurring in that situation in the first place.

I'm trying to understand this simulation business. I am using the critical eye of Christopher Timpson in 'Quantum Information Theory and the foundation of Quantum Mechanics'. He argues that your/Deutsch's argument is a 'simulation fallacy': that simulation is not a like for like business. Here are a couple of directly relevant paragraphs. Do you have a Deutsch rebuttal to this line of argument? It's part of a wider case, as I grasp it, that Deutsch is conflating the mathematical and the physical in 'the Turing principle' through a misunderstanding (in Timpson's view) of the original thesis. — mcdoodle

A rebuttal of what? The claim that Shor's algorithm does not require an astronomically vast number of parallel processing channels in or order to work?

We already know, based on every QM experiment ever performed, particularly interference experiments, that the classical idea that there is only one universe is destroyed. Despite the mis-representations of Timpson, the argument is not that parallel processing takes place therefore there are parallel universes, but precisely the opposite!

Logically, the possibility of complex quantum computation adds nothing to the argument already made. It is because parallel universes exist, that quantum computation possible! Please don't forget, that we know of these universes, but we don't know how to make a quantum computer! Shor's algorithm hasn't actually worked yet!

It is probably worth pointing out, that quantum computers were discovered by Deutsch as a by-product of thinking about how to test Many Worlds.

Deutsch is on record stating that the main impact of the first quantum computer will be psychological. And if you follow the references in Timpson's thesis to Deutsch's book, he explicitely states that the argument from Shor's algorithm is for "psychological impact".

You should also read note 8 of Timpson's thesis.

the classical idea that there is only one universe is destroyed. — tom

Bam! There's your slam-dunk McD. You're powerless in front of that. To oppose it is to be declared an 'enemy of reason'.

At about 2:00 Deutsch says that the existence of computation explains the unreasonable efficacy of mathematics in the natural sciences. I really don't get that. No computer or computational process could exist were it not for mathematics in the first place. Isn't it putting the cart before the horse? How come 'computation' is assigned to this kind of quasi-deistic role in Deutsch's worldview? 'There is a law of nature that the universe is computable, or that a universal computer exists'. — Wayfarer

The point is that the mathematics that we can perform - including proofs - is determined by the laws of physics. This also goes for the computations that any physical system can perform. This is why some functions are computable, but most are not.

Life is essentially a computational process, which you claim can not exist prior to mathematics. While it seems that the timeless truths and objects of mathematics must have always existed, I'm not convinced that they cannot be regarded as novel at the time of their discovery, or rather, invention.

Bam! There's your slam-dunk McD. You're powerless in front of that. To oppose it is to be declared an 'enemy of reason'. — Wayfarer

Denial is always an option. People do it all the time, just ask a creationist.

Despite the mis-representations of Timpson, the argument is not that parallel processing takes place therefore there are parallel universes, but precisely the opposite! — tom

The point is that the mathematics that we can perform - including proofs - is determined by the laws of physics. This also goes for the computations that any physical system can perform. This is why some functions are computable, but most are not.

Life is essentially a computational process, which you claim can not exist prior to mathematics. While it seems that the timeless truths and objects of mathematics must have always existed, I'm not convinced that they cannot be regarded as novel at the time of their discovery, or rather, invention. — tom

Well, I see this is one crux of the question.

If I am understanding the disagreement correctly, it does boil down to how one interprets Turing in the first place, and what in one's opinion comes first, the maths or the physics. Timpson says that Turing was writing in the 1930's when 'computer' actually meant a person doing computation, as distinct from 'machine', and it was his insight in relating the two that convinced Godel to accept his basic principle. The original Turing notion was about 'every function which would naturally be regarded as computable'. (That quote is Deutsch's summary of Turing) Timpson goes on to argue that Deutsch has gone on to argue what you're arguing, when in Timpson's view the Turing notion is about what humans regard as computable. Here's a quote from Chapter 6:

We always need to start with a putative computational model, a listing of states and their evolutions one is considering; and given such a model, it will precisely be logic (and mathematics) which will determine what could be computed by such a system and thus provides a limit. Physics provides no constraint at this stage. Physics only gets into the game afterwards, when we ask whether or not those states and evolutions can be physically realized. The mathematical (definitional) and the physical are very different kinds of constraints; but both are important. — Timpson

So for Timpson physics 'only gets into the game afterwards'. The humans assess the parameters of what can be computed, then examine whether these parameters are physically possible.

Deutsch’s emphasis on the possible physical existence of the universal computing machine, encapsulated in his Turing Principle, misrepresents its significance; missing the definitional role of determining the mathematical meaning of the evolution of physical states. — Timpson

These are two different methodological claims, although to me Deutsch's and yours are metaphysical: a claim to know the nature of the world, 'Life', and that it's computational: whereas Timpson is making the lesser claim, which is also what he believes Turing to have been claiming, that humanity assesses functions that might be computable, then considers what physics constraints there are on such computation. It's hard for an outsider to see them as anything other than metaphysical choices which one will make in accordance with one's wider beliefs and one's own response to the way the arguments are put.

The point is that the mathematics that we can perform - including proofs - is determined by the laws of physics. — tom

I really see how that is logically sound. We wouldn't know the first thing about laws of physics without first being able to grasp mathematical ideas and logical laws. So from what I can see, I'm inclined to agree with Timpson.