I can’t speak on the more scientific aspects of that paper, but on that final section, although it’s the case that any randomly selected brain is most likely a batty brain, it’s also the case that any randomly selected non-batty brain is most likely a Boltzmann brain. — Michael

Yep, I think that's right.

But there is a further step. There are far more batty brains than Boltzmann brain. But there is a further step. Supose you are a quantum fluctuation, having just popped into existence last Tuesday. The chances of you persisting into the next few seconds are vanishingly small. Chances are the world around you is ephemeral, and will disappear, or at the least not continue in a coherent fashion.

And yet for us, the world continues on in a regular and predictable fashion. Well, at least outside of dormitory kitchens.

And that is the argument from Batty Brains - that the world persists shows that it is very unlikely that you are a Boltzmann brain.

That seems to be how the argument goes.

There might had been a situation... — Corvus

Well yes, there are good reasons to doubt that the cup will remain in the cupboard. The point here is simply that your "when I am not perceiving the world, there is no reason that I can believe in the existence of the world" is not a good reason to think that the cup has disappeared from the cupboard.

If you were buying some coffee... — Corvus

This had me puzzling. How do you go about buying coffee? There's the package on the shelf at the store, brightly labeled "Dark Roast". But when one is not perceiving the coffee, there is no reason that one can believe in the existence of the coffee. Hence there is no reason to believe the label on the package. Does one tear the pack open to confirm the contents? But when you drop it into your shopping bag, you again cease to have reason to believe in the existence of the coffee! LIfe becomes difficult, for both you and store security.

Object permanence develops in a wee babe, and for some disappears during undergrad philosophy courses.

When first I played with ChatGPT I had it "prove" 999983 is not a prime - it just baldly asserted that it was the product of two integers. Then correct itself. Regretfully, I was using the playground so the record is lost.



They are coming out of the woodwork now.

Here's perhaps the original paper in which the mad brain response is worked out: You are not a Boltzmann Brain

Yeah, I recall that. Still can't make sense of it.

Just to be clear, my use of ChatGPT here is purely rhetorical, intended for amusement.

ChatGPT
The use of "=" to signify both equality and identity in different mathematical contexts doesn't necessarily imply an inconsistency in mathematics. Instead, it reflects the flexibility and versatility of mathematical notation to adapt to various branches and subfields within mathematics.

Mathematics is a vast and multifaceted discipline, encompassing diverse areas such as arithmetic, algebra, calculus, geometry, logic, and more. Each of these areas may have its own conventions, definitions, and notational systems tailored to the specific concepts and structures being studied.

While "=" is commonly understood to denote equality in basic arithmetic and algebra, its use to signify identity in formal logic or set theory arises from the need to express relationships between objects or sets in a precise and rigorous manner.

Inconsistencies in mathematics would arise if there were contradictions or logical paradoxes within a particular mathematical system. However, the use of "=" in different contexts doesn't inherently introduce inconsistencies; rather, it reflects the richness and diversity of mathematical language and notation.

Chat GPT does not lie you know. — Metaphysician Undercover

While "=" is commonly used to signify equality in mathematics, in certain contexts, particularly in formal logic or set theory, it's used to denote identity.

In basic arithmetic and algebra, "=" is indeed used to indicate equality between two expressions, stating that they represent the same value. For example, 2+3=5 asserts that the sum of 2 and 3 is equal to 5.

However, in more advanced mathematical contexts like set theory, "=" is sometimes used to signify identity, indicating that two objects or sets are the same in every aspect. For instance, in set theory, if sets A and B have exactly the same elements, we would write A=B to denote their identity.

So, you're correct that "=" can signify identity in certain mathematical contexts, particularly when dealing with formal logic, set theory, or higher-level mathematics. Thank you for pointing that out! — ChatGPT

:wink:

You made the marks. You uttered the words. You asked the question.

Three acts? Or one under three different descriptions? Either way, you asked a question by writing a sentence, and wrote a sentence by making marks.

other — NOS4A2

Other than what? You made some marks. An act. You wrote something. An act. You asked a question. an act. Would you like to count this as one act or as three? I don't much mind.

But would you have asked the question without writing? Or written without making marks?

Or are more acts occurring? — NOS4A2

So you made some marks on a screen. Did you also write something? And did you also ask a question?

You tell me. If all you did was make marks on a screen, then there is nothing to answer.

Have I performed any other act? — NOS4A2

IS that a question? Or only a bit of writing?

You didn't also and thereby ask any questions or make statements?

Well then, what am I to answer here?

Ok.

If you want me to pick at this some more, I'd say that the conclusions reached by such arguments, especially in pop literature and in these fora, are overblown.

But yeah, sure. Cheers.

A bit more - again, the showing is what counts here - all this might well be the construct of a random quantum fluctuation... but if I don't go water the plants, they will die. It's what we do that counts, action over theory, meaning as use.

“I am Banno” and “I am a Boltzmann brain” are not in conflict. — Michael

Sure. That does not render Boltzmann brains true. Again, I don't see a need to "resolve" the issue; indeed, I don't see that it could be resolved.

There's plenty of insuperable philosophical issues, and it's easy to make up even more.

But, so far as this thread goes, if Boltzmann brains exist, that shows that there is a world.


(Edit: just to be sure, I'll maintain that the person to whom you are talking is not a Boltzmann brain, even if a Boltzmann brain is somehow imagining him...)

How would you resolve that apparent contradiction without resorting to special pleading? — Michael

I don't see a need to "resolve" the issue.

But if pushed I'd use much the same sort of argument I used against reincarnation - what is the "I" in "I have been reincarnated"... and what is the "I" in "I am a Boltzmann brain"? I am not a Boltzman Brain, nor am I the reincarnation of Cleopatra. I am Banno.

The questions are: how are these acts distinct from the act of speaking? Where in space and time occurs the performance of these acts? Where in space and time lie the consequences and effects of these acts? Is a speaker actually doing something with words? — NOS4A2

Haven't you here both spoken (written...), and asked a series of questions?

...good reasons... — Michael

Then perhaps our only point of difference is, what reasons are to count as "good"...

:wink:

But there's a further issue we might consider, in that so many of the posts in this thread attempt to argue for the existence of the world from physics (without the maths).

That has to strike you as circular, doesn't it? Arguing from a description of the world to the existence of the world?

If you are convinced by Boltzmann to believe you are a Boltzmann brain, then the universe is pretty much as physics describes it, since that description - physics - is what Boltzmann uses to reach the conclusion that you are a Boltzmann brain...

And yet somehow the argument is seen as reaching the conclusion that the world is not as it appears...

And how would you reply to each of these counterpoints, were you arguing my view?

Your responding to me is not an argument for the world. It cuts all that rationalisation out, instead showing your participation in the world. PI §201, again.

Hence any doubt is infelicitous. We should then ask 's question.

This presupposition of the existence of the outside world is not needed for the discussion to happen, as the discussion could be a projection of the mind; — Lionino

Perhaps at the very least it presupposes that solipsism is false. It need not presuppose the existence of a material world (e.g. it allows for idealism), or that the world we experience is that material world (e.g. it allows for us being brains-in-a-vat). — Michael

I dunno. It seems to me that you should have difficulty in denying the existence of these words, even as you are reading them.

How can that be?

It seems to me that you must conclude that there is something more than just your thoughts.

But having established that there is something more than just your thoughts, we might press the argument further.

Novelty. We are sometimes surprised by things that are unexpected. How is this possible if all that there is, is already in one’s mind?

Agreement . You and I sometimes agree as to what is the case. How is that possible unless there is something "external" to us both on which to agree?

Error. We sometimes are wrong about how things are. How can this be possible if there is not a way that things are, independent of what we believe?

Again it might be worth pointing out that philosophy is hard. Each of these points needs a PhD, if not a career, to be treated adequately.


I guess the upshot is that it is somehow quite implausible to question the existence of a world around you, whilst all the while participating in it.

I do not think I was ever subjected to new math. — Metaphysician Undercover

Ok. So we still have no explanation of how you came to misapprehend "=".

You can justify that by saying that the symbol Canberra does not elicit any thought in your mind, but that is just equivalent to saying you don't know what Canberra is. — Lionino

yep.

Beyond the circular justification above, it is close to a brute fact, somewhat similar to the cogito. — Lionino

Yep.

Comes in the main from Wittgenstein. See On Certainty.

The discussion in this thread, like all discussions, presupposes the existence of an "external" world in which the discussion is taking place...

Odd, don't you think?

There are many other things that can be discussed in the thread — Corvus

The cups are simple, clear and shows up the issues in a way that other examples tend to obfuscate.

The claim from the OP is that when one is not perceiving the world, there is no reason to believe in the existence of the world. You put the cup in the cupboard. You are no longer perceiving the cup. Therefore, the argument goes, you have no reason to believe that the cup exists.

You put the cup in the cupboard. I ask you to hand me the cup. Do you get it out of the cupboard or do you say "I don't know where the cup is"?

It's a pretty simple example that shows the absurdity of ill-placed doubt.

Of course it's an interesting topic. These considerations deserve attention, as part of "Discussing the nature of the beliefs and doubts and logical grounds for them". This argument is central to this topic. Doubt should not go unquestioned.

No I cannot. — PL Olcott

Yeah, didn't think so.

When I address every possible objection that anyone can possibly have I have address his objections. — PL Olcott

Sure, good, wonderful.

Now, can you set out the objections raised by Quine, and how it is that you address them?

Otherwise, it seems to me that your definition of analyticity is just the first one that Quine sets out -

If we suppose a prior inventory of logical particles, com-
prising 'no', 'un-', 'not', 'if', 'then', 'and', etc., then in general a logical
truth is a statement which is true and remains true under all reinter-
pretations of its components other than the logical particles. — p.23, your reference

Yeah, I'm quite familiar with the paper.

What are his objections, specifically, and how does your account address them?

SUre, all that.

So what were his objections? The ones you refer to in the title of this thread?

..do I need a foundation to state that? — Lionino

What do you think? Or is "I don't know what Canberra is" foundational?

What justifies believing "I don't know what Canberra is"? Isn't that question somehow inept?

...but if by doubt you mean "I don't know if", you would not need a foundation for doubting... — Lionino

Wouldn't that you don't know the meaning of "Australia" be the background for your doubt?

Ok.

So the objections that you point to in the title of this thread - what exactly are they?

Ok, and it is synthetic. So there are synthetic facts?

SO facts divide into synthetic and analytic?

Quine didn't seem to understand that facts are analytic. — PL Olcott

There are synthetic facts, too. So what is it that Quine did not understand?

But is it a fact?

I'm asking if it is a fact that there is a small black dog in your living room right now, given that there is a small black dog in your living room right now.

That there is a small black dog in my living room right now is synthetic. — PL Olcott

SO, on the presumption that there is indeed a small black dog in your living room right now, and the view that facts are analytic, does it follow that it is not a fact that there is a small black dog in your living room right now? And this despite there being a small black dog in your living room right now?

Not following that.

, . Perhaps the emphasis on imagination in some maths teaching is what leads to those here who insist on the truth of their mathematical intuitions despite demonstrations that they are mistaken. Is @Metaphysician Undercover a product of the New Maths? :wink:

The problem for curricula is that there is of course no one way to teach, each individual having different needs and backgrounds. What is required is trust in the teacher's ability to recognise and adapt their teaching to the student. But that's contrary to the very notion of a curriculum.

...when I am not perceiving the world, there is no reason that I can believe in the existence of the world. — Corvus

So you have no reason to believe in the existence of the things behind you? When you put the cup in the cupboard, you cease to have any reason to believe that the cup is in the cupboard?

That's not right.

The response I think most telling is from On Certainly. Doubt requires a foundation. In order to doubt that Canberra is the Capital of Australia, you need a background understanding of "Canberra", "Australia" and "capital", as well as a comprehension of how to articulate these into the proposition to be doubted.

You can doubt anything; but you cannot coherently doubt everything.

But this is not the argument in this thread. That is specifically about not believing that something continues to exist, unperceived. A very silly argument.

Threads such as this are interminable because, even after being shown the way out of the fly trap, some flies will say "Nah, I'm good."

Brain in a vat. — Lionino

I'm not seeing how this relates...

You see, if you are a brain in a vat, then there are vats and brains.

That is, there is still an "external world".

Thoughts?

Righto.

Curious, that this discussion is occurring in the world that the participants call in to question.

A bit of a performative contradiction, no?