#Infinitism Vs Finitism

357 messages · Page 1 of 1 (latest)

keen marlin
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I actually think you can variably prove infinity to be present within this world using cantor's diagonal argument, which would entail aleph 1 being real, logically making aleph null (baseline infinity) real (or possible)
I'd like to hear other peoples perspectives/ reasoning for whatever side they choose

burnt otter
deft quest
burnt otter
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Yeah. And your argument that the existence of ℵ₁ implies the existence of ℵ₀ is unjustified. Not to mention that the diagonalization argument itself assumes the existence of infinite strings of digits. Please elaborate.

urban perch
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thats not forbidden

urban perch
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work with whatever formal system you want

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neither infinitism nor finitism is 'better' than the other

somber shell
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I like that

ruby cairn
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I think it has to do with interpretation

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I think you can encode infinitism in finitism

urban perch
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inuitionism doesn't permit nonconstructive arguments

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at the very least, the "encoding" will be difficult

ruby cairn
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What's finitism and infinitism actually?

urban perch
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broadly speaking, finitism = "only finite objects exist"

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for intuitionists infinite objects like infinite sets don't (and can't) exist

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the word "exists" is also another can of worms, entirely

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their definition of N (the naturals) has something to do with memory capacity of computing devices

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it's not a completely unreasonable position to take - computers don't "understand" and can't model the concept of "infinity"

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any computer is bounded by 2^N bits of data, presumably there being some theoretical upper limit to maximum memory capacity

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none of this is rigorous, take it as a tongue-in-cheek

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rigorously speaking however: given sufficiently sophisticated formal system (one that encodes the arithmetic of N), the only way we have for determining whether it is "good" or "bad" is whether or not it produces contradictions

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if we don't allow infinite objects, that's fine - but then that formal system wouldn't be useful for analysing infinite dimensional banach space theory

valid hazel
urban perch
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also possible

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I've also heard a certain mathematician saying the largest natural number is one that will be referenced by humans

valid hazel
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Yes, those are ultrafinitists.

valid hazel
urban perch
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disagreements naturally arise

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mathematically speaking one should only worry about what the basic truths (axioms) are and what can be deduced from them

valid hazel
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Yes, but you can dispute over the basic truths.

urban perch
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for something like CS, I would actually prefer constructivist approaches

valid hazel
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Yes, same here.

urban perch
valid hazel
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Indeed, but I don't really think there is nor ought to be a clear dermarcation between philosophy and all the other disciplines.

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It's not as if our mathematical axioms (which tend to be formulated in natural language) and proofs which are accepted by other mathematicians just popped out of the ether.

urban perch
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im a mathematician, i am by default equipped to sh.t on philosophy 😂 noway

valid hazel
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yeah, people tend to (mainly people who know nothing about it!)

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though i wouldn't say you're equipped to

urban perch
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😂

valid hazel
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ig maybe you are

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like, a large number of post-20th century philosophers who started the analytic tradition had firm mathematical background for a reason

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it's hard to interface with a lot of analytic philosophy without a firm logic background

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im also compelled to shit on philosophy, but i don't really share the same tendency to just outright dismiss entire fields of study like some people do

urban perch
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difficult to put my position into words tbh

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empirically speaking, such discussions (for me) have sooner or later come down to personal beliefs

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i can't deny someone their belief

valid hazel
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Ah, is the idea that certain disputes aren't empirically verifiable, and thus there is no real way to justify one view being correct over the other, or...?

urban perch
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something like that

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math is simple in this regard

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the rules of the game are fixed

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but I don't know what the whole rulebook of philosophy is

valid hazel
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kind of, the rules of the game are less apparent than you'd think

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i have a natural inclination towards the accounts of people like Reuben Hersh or Imre Lakatos

urban perch
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hence I am content with all formal systems existing, their usefulness dependent on context

valid hazel
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i mean, intuitionists don't tend to say "this formal system is haram" or something

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it's much more like "in reality, PEM is false"

urban perch
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my belief (yup, here we go 😄 ) is that usefulness of theory A or B is dependent on context

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what sort of problems are we trying to analyse

valid hazel
urban perch
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fair

valid hazel
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That doesn't counteract any grand view though. Like, here's a good example of a view a lot of people who endorse classical logic hold: the very meaning of negation entails the PEM, so intuitionist logics negation means something different.

urban perch
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for example, I would (in most cases I can think of) require axiom of choice for banach space theory

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and a lot of theory I am familiar with is predicated on the Hahn Banach theorem

valid hazel
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Yes, well, keep in mind, most people do not want to put a ban on working in systems that contain AC as a theorem.

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Like, formal systems are kind of divorced from what people who have these disputes care about

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This is coming from someone who doesn't really think there's a fact in the matter of whether AC or PEM is true

urban perch
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PEM

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excluded middle ?

valid hazel
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Yes, PEM is LEM for people who don't want to call it a law, common sometimes among (certain) intuitionists

urban perch
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understandable

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side note: choice implies PEM

valid hazel
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Yes

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Which is why intuitionists have to reject it 😆

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No, some philosophers (who are also mathematicians) of mathematics like to do a thing where they argue for some super intuitive thing Q, say it's true, and then show Q entails something like choice or the continuum hypothesis or something

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What Woodin is doing comes to mind

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However, this is all meaningless if you don't believe in what are frankly magic objects floating in the ether (mind-independent, aspatiotemporal "abstract objects")

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I am reminded of how funny this is

urban perch
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oh boy ..

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I was in some argument with one N. Wildberger some years ago over some philosophical mumbo jumbo

valid hazel
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Oh, how did that go?

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You say "mumbo jumbo," so I assume you didn't know what the words he was using meant.

urban perch
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he did enjoy sophistry, certainly

valid hazel
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Exciting stuff, but this N J Wildberger fella I find online has a text literally titled "Divine Proportions"

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Which is not a uh, good sign

urban perch
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he had an annoying condescending tone

valid hazel
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ah, yeah, well that sucks

urban perch
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basically we were talkig about one of his essays where he criticised the ZFC axioms

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I just should have known better that this premise alone is enough reason to avoid engaging with him altogether

valid hazel
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eh, not all philosophers online are assholes (or sophists)

urban perch
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but I was in my "I feel like a god" stage of my math education

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feeling like I should "save everyone"

valid hazel
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saving everyone is a very noble goal, even if it is ultimately very misguided

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so, what happened?

urban perch
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he talked in circles

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I pointed that he is attacking his own strawman multiple times in the essay

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essentially, he didn't criticise the axioms

valid hazel
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damn, this guy seems somewhat respectable, teaching at UNSW

urban perch
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but rather his understanding of the axioms

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which is pointless, imo

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yes, and also dabbles in some very non trivial math

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has written papers on Lie theory to name some

valid hazel
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yes, i am looking through his stuff on ResearchGate

urban perch
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he also does youtube, and he has a series on history of math

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which I enjoyed a lot

valid hazel
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that's pretty good, he teaches history of mathematics at UNSW so it makes sense

urban perch
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but then he's hellbent on redefining analysis

valid hazel
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if you like history of mathematics, i recommend you check out joel david hamkins

urban perch
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because the "real numbers" don't really make sense

valid hazel
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ah, so it's some novel new type of analysis?

urban perch
valid hazel
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indeed!

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I was going to say

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just now

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"you may have seen him on mse or math overflow"

urban perch
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but he quantifies over Q

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because that's somehow qualitatively different 😮

valid hazel
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does he just dislike uncountability or something

urban perch
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Q seems ok so he's not ultrafinitist

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or maybe he is, I don't know to be fair

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he has said something about there being the largest natural number

valid hazel
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he probably dislikes R because equality is not computable or something

urban perch
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something about it is unintuitive for him 😄

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..pun intended

valid hazel
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haha

urban perch
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i dont rightly understand his position

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Q seems fine for him

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but he has also criticised the axiom of infinity

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so he can't accept N (as an infinite set)

valid hazel
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well, that's probably fine, it may be incoherent or something, but it also may be he didn't explain it well, or you don't have the philosophy background to make sense of his bad presentation or something, or a combination of the three

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most likely a combination of the three

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weird positions require a lot of deciphering to make sense of

urban perch
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i'd assumed elementary logic would be enough

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not PEM, but that's fine

valid hazel
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eh, it probably is actually

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sometimes there are weird philosophy-specific things, and if you touch enough logic, that's kind of inevitable since logic is basically at the junction between philosophy and mathematics, so the distinction gets fuzzy there

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i'll try to read some of this guys stuff

urban perch
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but whatever my disputes with him, he definitely knows math, it's not all bogus stuff on his channel

valid hazel
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okay, from his overview of Divine Proportions, his concern is that a lot of contemporary geometry is hard for people to understand because of the semantic vagueities of "infinite set theory"

urban perch
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oh yeah, he definitely doesn't like axioms

valid hazel
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what he's doing doesn't actually seem all that bad, especially given how nice sufficiently weak systems are

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i think his idea is actually just that we don't really have any understanding of this "infinitity stuff," so we should avoid it

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which isn't all that bad, but i don't know what he uses to argue this is the case and what-not

urban perch
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and if he did say it like that, that would be fine with me

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but he gets veeeery condescending

valid hazel
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ah, that's a real shame, seriously

urban perch
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he claims that the ancient greeks and the reneissance folk were much more rigorous than we are today

valid hazel
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haha, well it's hard for me to comment since i don't really know what he means by that, ancient greeks surely didn't prove theorems that turned out to be equivalent to AC in natural language, that's for sure

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greeks didn't have any formal axioms or anything, obv

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no formal proof checkers or anything either

urban perch
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theory wasnt as developed in the early 19th cty so many mathematicians/physicists used some claims because they were intuitively correct

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famous example: continuous functions are differentiable almost everywhere

valid hazel
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yeah, it's just plausible the dude thinks this is still the case more than we let on

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bc of the axioms he doesn't like or something

urban perch
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and even more famous counterexample: weierstrass's continuous nowhere differentiable function

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and even more, if what wildberger claimed was true

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why oh why did hilbert go on to do what he did?

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did the rigour of our ancestors got sucked into a black hole or something?

valid hazel
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Are we talking about Hilbert's formalism stuff

urban perch
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hilbert's programme i think it's called

valid hazel
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Yeah, well sadly that failed

urban perch
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but a good endeavor nonetheless

valid hazel
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Indeed

urban perch
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pushed people like turing and gödel

valid hazel
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There are systems like relevant PA (PA closed under entailment in relevant logic) which have finitistic proofs of their consistency, which is neat

urban perch
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good talk, gotta make dinner, tc buddy

valid hazel
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alr, have fun and eat well

keen marlin
keen marlin
# keen marlin Dimensional space

I totally acknowledge I could be wrong, which is why I said I think you could variably prove infinity to exist
Question to think about: How many squares are in a cube? (Hint: It's not 6)

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If we break a cube down

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There's an aleph 1 amount of squares

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Another way to think about it: How do you go from a square to a cube with just squares? You need to somehow increase the third dimension from 0 to any positive number
How many numbers/decimals are there inbetween 0 and 1? Cantors diagonal argument pretty much self explanatorily applies to the amount of squares with no third dimension to make a third dimension

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But other people could say something 2d doesn't exist and that it's an axiom
Which is again why I said variably since it depends how you look at it

deft quest
deft quest
# keen marlin There's an aleph 1 amount of squares

No, there isn't. A square is a shape with literally zero thickness, any "slice" off of a cube must have a nonzero thickness. You can take the limit as the thickness approaches zero, but that's not remotely the same thing. A limit approaching 0 is not a value that achieves 0. Also this has nothing to do with Cantor diagonalization, and also also this presumes the continuity of space, which is supposedly the thing being proved, which makes it circular.

keen marlin
keen marlin
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keen marlin
keen marlin
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# keen marlin And I'm not old enough

So if you think you have a revolutionary theory about some field of math or science, but you're too young to have learned the math that is literally freshman level in that field, what's more likely; that you've noticed something that everyone else has missed, I guess because they were too busy going to all those classes you haven't taken, or that you've missed something that everyone else has noticed, maybe in all those classes you haven't taken?

keen marlin
# deft quest So if you think you have a revolutionary theory about some field of math or scie...

'the math that is literally freshman level in that field'. Calculus is part of set theory?
I quite literally said I acknowledge I could be wrong, and I wasn't expecting to run into passive aggresive adults on this app who have degrees in maths? I thought someone with such knowledge wouldn't be sat in discord servers but I guess I was wrong
And do you have selective reading? Why only respond to some of what I've said

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From what I've gathered on google, set theory is the standard foundation

deft quest
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..."freshman level" means "taught to college freshmen".

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Something you learn in the first year of college.

keen marlin
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So you're an adult?

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Not too sure what you're clearing up

deft quest
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And I'm not being passive aggressive, I'm making the point that you should take, like, literally any effort to seriously investigate an idea before you present it.

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And if even that much feels over your head, you should acknowledge that you're probably just wrong.

keen marlin
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keen marlin
keen marlin
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And again

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Let's circle back to the selective reading part

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I'll ask again

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How old are you?

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keen marlin
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Third time asking so hopefully will bypass your selective reading

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How old are you?

deft quest
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It's not "selective reading", it's ignoring pointless nonsense.

keen marlin
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I would like to know the age of the person I'm engaging in conversation with thank you

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You say calculus is something taken in first year of college, I'm asking how old you are to see if I can figure out if you've taken it or not, or how deep you are in mathematics

deft quest
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I would like a billion dollars and a trip to the Moon.

keen marlin
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I'm deducing from this you're either a child or an adult with a short temper

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Based on your reply earlier, one with negligible comprehension skills and as established, no common sense

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Nice chat

deft quest
keen marlin
# deft quest This is literally the first thing I said. Do you think *this* was passive aggres...

I think it encompassed unnecessary remarks
What I said did make sense, just not to you
Which now makes sense since we've established you've got no common sense
You could've simply asked me to elaborate/explain
I read 'How in the hell do you plan to-' with multiple dots to be passive aggressive
Although that could've been deduced with critical thinking from my previous replies on the topic... (yes this is me starting to be passive aggressive)

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You have time to type all this but not 2 numbers

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Well I'm hoping for 2 numbers

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keen marlin
keen marlin
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keen marlin
valid hazel
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So, what I am trying to salvage out of 4 or whoever's beliefs (if we are to be charitable and call them that) is that

  1. Space is continuous
  2. If space is continuous, it is infinitely divisible
  3. If space is infinitely divisible, then infinity is "actual," thus infinitism is true
  4. Thus, infinitism is true

The best support I can give for 1 is in terms of the fact our best scientific theories commit us (to my knowledge) to a continuous view on space. GR doesn't make sense, to my knowledge, if spacetime is discrete, since uh, differentials and all. Premise 2 seems to be true, and 3 is dubious for obvious reasons.

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valid hazel
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Uh, I can explain more if you'd like.

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valid hazel
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Yes, but that doesn't mean you wouldn't prefer I explain for others, no?

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Such as middle schoolers who you think want to talk about infinitism.

valid hazel
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Well, that's quite a shame.

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I have no clue what you're trying to say, then.

valid hazel
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I can't get over "realism" in your bio as if it is one specific position.

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Are you a realist about everything, haha?

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Numbers, God, also nonexistent objects, necessary beings that entail trivialism, et cetera, y'know?

keen marlin
# valid hazel I have no clue what you're trying to say, then.

Think of it less as dividing
Imagine a cube in your mind
How many squares make up that cube?
I'm not necessarily saying you can divide a cube by aleph 1 and you end up with a square
I'm saying looking at it from an upward perspective (if that at all makes sense) how many squares are needed to become a cube/cuboid. How many of these structures with no third dimension do we need to stack behind each other to give them a finite third dimension
Now back to the cube, let's say it has a width of 1 cm, height of 1 cm, and a length of 1 cm
We have 1 by 1 squares
How do we get that 1 by 1 square to a 1 by 1 by 1 cube?
You're going from 0 to 1
There are the same amount of 1 by 1 squares needed to make a 1 by 1 by 1 cube as there are decimals between 0 and 1
Which is why I said using cantors diagonal theory
The other guy who responded didn't understand my argument
The point is, I understand I might be wrong/ probably am, I'd just like someone to understand my theory before refuting it/ explaining to me why it's wrong

deft quest
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Meinong's Jungle Book.

valid hazel
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Yes, well, sadly Meinong gets dismissed without thought because his view seems too absurd to people, since a lot of people are kind of bigots.

keen marlin
valid hazel
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Russell does do a good blow to a lot of the reasons for Meinongianism though.

keen marlin
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valid hazel
valid hazel
keen marlin
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I'm just gonna leave it here cause it makes sense in my mind and I'm just struggling to convey it in an understandable way

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valid hazel
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Yeah, so I think you're under the impression squares have some infinitesimal width or something.

keen marlin
deft quest
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Which is literally the thing you're trying to prove in the first place.

keen marlin
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Oh

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Bye

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I didn't read

valid hazel
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no dw

keen marlin
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Infinitesimal is also basically 0

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Unless it's a percentage

deft quest
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No it very much is not.

keen marlin
valid hazel
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What is there to debate over

deft quest
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An infinitesimal is literally by definition not 0.

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It is literally by definition the smallest number greater than 0.

valid hazel
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Like, it's just false

keen marlin
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Which is why I said 'is also basically 0'
By definition it isn't, but it practically is

valid hazel
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Infinitesimals are not additive identities

keen marlin
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That's like saying 0.9recurring isn't 1 by definition but it basically is

valid hazel
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It is, by definition, if you actually define 0.999... more precisely (in terms of limits, usually)

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keen marlin
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You're not the penultimate consciousness

valid hazel
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What is there to debate over? It's just false, no strings attached, unless you're going to bring in some weird verisimilitude notion here.

deft quest
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You haven't even taken calculus! What do you know about infinitesimals???

keen marlin
valid hazel
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Eh, most calculus is not non-standard analysis, TL.

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Most calculus students don't know anything about infinitesimals either. They're just a nice intuitive shorthand for doing limits, generally, almost never are they formalized.

deft quest
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That was more "you're so far below the level where you would know anything about this", not "you haven't taken the specific class that would teach you about this".

valid hazel
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Ah.

keen marlin
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What is up with the aggressive comments along side the ducking..
If you think you're so right then why not agree to debate this?

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You think you're right, I think I'm right, let's debate it

deft quest
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Because literally your position in the "debate" is that the definition is wrong.

keen marlin
valid hazel
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I mean, I don't think I've been rude to you much, 4.

keen marlin
valid hazel
keen marlin
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keen marlin
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Which is why I asked to debate it

deft quest
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Who's stopping you???

keen marlin
valid hazel
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4, infinitesimals are kind of an abstract mathematical notion, I don't know if you're trying to tie it to something more physical in nature, by infinitesimals are defined in such a way that they do not resemble zero in any non-negligible way structurally.

keen marlin
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I agree with you in a sense

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I just don't think it's entirely correct

deft quest
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What the fuck does "penultimately correct" mean???

keen marlin
deft quest
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That's not remotely what the word "penultimately" means.

valid hazel
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In second place for correctness, I presume.

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0 is typically supposed to be defined such that for all a, a + 0 = a, no? However, a + epsilon (where epsilon is some infinitesimal) does not equal a.

keen marlin
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valid hazel
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Eh, you mixed up ultimately and penultimately, which happens, don't worry about it.

valid hazel
keen marlin
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I think there's a difference between 0% and an infinitesimal percentage
I don't think an infinitesimal decimal is different to 0

valid hazel
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You are right than infinitesimals have the nice property that a + k*epsilon for any natural k is always less than a + j for any real 0 < j.

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keen marlin
valid hazel
valid hazel
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keen marlin
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I'm going out now but I can explain why I think that later

valid hazel
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Infinitesimals do not have decimal representations in the usual sense.

keen marlin
valid hazel
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Hey, if you would like to elaborate sufficiently, just write one long post when you get back.

keen marlin
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valid hazel
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If then, still, I or TL (if they still are entertaining this discussion, which they have no obligation to) do not understand, then it is probably because of an issue on your part, frankly. I do not think it's because TL is dumb or something.

keen marlin
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Totally fine

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valid hazel
ruby cairn
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How about the inductive type definition of the naturals in lean. Would that be a finite object or an infinite object?

keen marlin
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Anyway

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I'll come bacj later

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valid hazel
deft quest
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It's not even intelligible! The closest analogue would be lim_(n -> inf) 1/10^n, which is just 0.

valid hazel
deft quest
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They literally said they're not old enough to have taken calculus.

valid hazel
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As I commented earlier,

Infinitesimals do not have decimal representations in the usual sense.

ruby cairn
valid hazel
deft quest
valid hazel
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I do not think bringing age into the discussion for frankly no reason. Some children are precocious, and it really just serves to enforce stereotypes about children rather than accomplish anything at all.

ruby cairn
valid hazel
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I have not seen anything by this "sheafification of g" fella.

ruby cairn
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To try everything Brilliant has to offer—free—for a full 30 days, visit https://brilliant.org/GSheaf/ . You’ll also get 20% off an annual premium subscription.

Finite numbers can be represented with finite strings of (decimal) digits, but what happens when we try to imitate this representation in the world of infinite numbers? In the world of o...

▶ Play video
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valid hazel
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This looks like a channel I would not enjoy watching.

ruby cairn
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How so

deft quest
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What the heck is an "infinite number"?

valid hazel
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I think they mean there are infinitely many numbers that have only finitely many digits, but I'm not sure, maybe they clarify in the video.

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I'm not going to watch it, since it seems like something that'd give me anxiety and is probably a load of pop mathematical hogwash, to be frank.

deft quest
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From the thumbnail, it looks like they're talking about numbers with infinitely many digits.

valid hazel
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Then uh, yeah, you'll probably have to watch their content to find out.

ruby cairn
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He presents it in a way enjoyable for skibidi toilet watchers ig

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But the mathematical content seems correct

valid hazel
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Okay, so from the 2 minutes that I watched of this guy, he is basically just using some intuitions about ordinal numbers and not formalizing anything, which is frankly fine, since it is targeted at "skibidi toilet watchers."

ruby cairn
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Yea