A) When a set is not a member of itself, it is a member of another set
B) When a set is a member of itself, it is not a member of another set — Philosopher19
Evidently, in A, A is a member of itself.
Evidently, in B, A is not a member of itself because A is a member of B. — Philosopher19
You are not a set. You can never be a member of yourself. But a set can either be a member of itself or a member of other than itself. And it is logically the case that when a set is a member of itself, it is a member of itself. And when it is a member of other than itself (as was the case with A in B), it is not a member of itself. — Philosopher19
A is a member of both A and B.
I'll explain it to you in non-math terms:
I am a member of the football team and a member of the tennis team.
These are two different claims:
1. I am not a member of the football team
2. I am a member of a non-football team
(1) is false and (2) is true. — Michael
I repeat:
A) When a set is not a member of itself, it is a member of another set
B) When a set is a member of itself, it is not a member of another set — Philosopher19
Regarding Russell's paradox, it is simply this:
1. x is a member of R if and only if x is not a member of x.
Is R a member of R?
Either answer entails a contradiction, and so (1) is a contradiction. Given that naive set theory entails (1), naive set theory is shown to be inconsistent. — Michael
z = any set that is not the set of all sets
v = any set
The v of all vs = the set of all sets
The z of all zs = The not-the-set-of-all-sets-set of all not-the-set-of-all-sets-sets — Philosopher19
Take z to be any set that is not the set of all sets, and take v to be any set. The z of all zs is a member of itself as a z (as in in the z of all zs it is a member of itself). But it is not a member of itself in the v of all vs, precisely because in the v of all vs it is a member of the v of all vs as opposed to a member of itself. If we view the z of all zs as a z, it is a member of itself. If we view the z of all zs as a v, it is a member of the set of all sets. You can't view it as both a member of the z of all zs and a member of the v of all vs at the same time. That will lead to contradictions. In other words, we can't treat two different standards/contrexts as one (as in are we focused on the context/items of vs or the context/items of zs to determine what is a member of itself or not a member of itself?) — Philosopher19
These are two different claims:
1. A is not a member of itself
2. A is a member of some other set
Given this:
A={A}B={A,0}
(1) is false and (2) is true. — Michael
THAT is dogma. You have no proof of it, and I gave an exact disproof of it. — TonesInDeepFreeze
z = any set that is not the set of all sets
v = any set
The v of all vs = the set of all sets
The z of all zs = The not-the-set-of-all-sets-set of all not-the-set-of-all-sets-sets — Philosopher19
Take z to be any set that is not the set of all sets, and take v to be any set. The z of all zs is a member of itself as a z (as in in the z of all zs it is a member of itself). But it is not a member of itself in the v of all vs, precisely because in the v of all vs it is a member of the v of all vs as opposed to a member of itself. If we view the z of all zs as a z, it is a member of itself. If we view the z of all zs as a v, it is a member of the set of all sets. You can't view it as both a member of the z of all zs and a member of the v of all vs at the same time. That will lead to contradictions. In other words, we can't treat two different standards/contrexts as one (as in are we focused on the context/items of vs or the context/items of zs to determine what is a member of itself or not a member of itself?) — Philosopher19
I think you can understand this if, for a few moments, you clear your mind of the voice in it that keeps saying "I am right. I know I am right. I must be right. All the logicians and mathematicians are wrong and I am right", then very carefully, very slowly, consider: — TonesInDeepFreeze
Is there any way you can provide an example of a set that IS a member of itself, other than the set of all sets, in plain language? I can't think of one. — Fire Ologist
I'm not sure I get what I'm saying. — Fire Ologist
Help me out. Besides the set of all sets, what is an example of a set that is a member of itself? — Fire Ologist
So revised: Let x not equal b. Let b not be a member of x. Let x be a member of x. But x is a member of {x b}. So x is a member of x and x is a member of a set different from x, viz {x b}.
That refutes your claim. — TonesInDeepFreeze
Wrong. You cannot produce a valid demonstration that — TonesInDeepFreeze
What you skipped is my refutation (posted twice) of your claim that a set can't be both a member of itself and a member of another set. — TonesInDeepFreeze
"is a member of itself, as a member of itself" has no apparent meaning to me. — TonesInDeepFreeze
You said that it is perhaps fair to say that such locutions have no apparent meaning, but then you proceed to post them again — TonesInDeepFreeze
The set of all sets is really the set of all members, which is also how we use the word "all" in the first place. — Fire Ologist
Isn't the set of all sets equivalent to the set of all members? — Fire Ologist
There aren't actually any sets within the set of all sets. There are only members. — Fire Ologist
A set of all sets has as members all the sets — TonesInDeepFreeze
I've refuted that claim. You skip the refutation. — TonesInDeepFreeze
So whether a set x is a member of itself or not a member of itself, if there is a set of all sets then x is a member of that set of all sets. — TonesInDeepFreeze
Take z to be any set that is not the set of all sets, and take v to be any set. The z of all zs is a member of itself as a z (as in in the z of all zs it is a member of itself). But it is not a member of itself in the v of all vs, precisely because in the v of all vs it is a member of the v of all vs as opposed to a member of itself. If we view the z of all zs as a z, it is a member of itself. If we view the z of all zs as a v, it is a member of the set of all sets. You can't view it as both a member of the z of all zs and a member of the v of all vs at the same time. That will lead to contradictions. In other words, we can't treat two different standards/contrexts as one (as in are we focused on the context/items of vs or the context/items of zs to determine what is a member of itself or not a member of itself?) — Philosopher19
I take you to be saying that a set cannot be a member of another set and also a member of itself. — TonesInDeepFreeze
Do you mean: If S is a subset of some set T and x is member of S, then x cannot be a member of T ? — TonesInDeepFreeze
That's incorrect. By the definition of 'subset', if S is a subset of T, and x is a member of S, then x is a member T. — TonesInDeepFreeze
Take z to be any set that is not the set of all sets, and take v to be any set. The z of all zs is a member of itself as a z (as in in the z of all zs it is a member of itself). But it is not a member of itself in the v of all vs, precisely because in the v of all vs it is a member of the v of all vs as opposed to a member of itself. If we view the z of all zs as a z, it is a member of itself. If we view the z of all zs as a v, it is a member of the set of all sets. You can't view it as both a member of the z of all zs and a member of the v of all vs at the same time. That will lead to contradictions. In other words, we can't treat two different references as one (as in are we focused on the context of vs or the context of zs?) — Philosopher19
An item in a subset cannot be both a member of the subset and the set. If it is a member of the subset, it is a member of the subset. If it is a member of the set, it is a member of the set. — Philosopher19
Something cannot be both a member of itself and a member of other than itself at the same time. For example, take z to be any set that is not the set of all sets, and take v to be any set. The z of all zs is a member of itself as a z (as in in the z of all zs it is a member of itself). But it is not a member of itself in the v of all vs, precisely because in the v of all vs it is a member of the v of all vs as opposed to a member of itself. If we view the z of all zs as a z, it is a member of itself. If we view the z of all zs as a v, it is a member of the set of all sets. You can't view it as both a member of the z of all zs and a member of the v of all vs at the same time. That will lead to contradictions. In other words, we can't treat two different references as one (as in are we focused on the context of vs or the context of zs?) — Philosopher19
Correct! Indeed that is a crucial point that is used in an important proof I gave you. — TonesInDeepFreeze
'There exists a z such that for all y, y is a member of z' contradicts this instance of the axiom schema of separation: For all z, there is a x such that for all y, y is a member of x iff (y is a member of z and yis not a member of y). — TonesInDeepFreeze
That is not "once again". Previously you said that "a set cannot be both a member of itself and a member of other than itself". That is different from "a set cannot be both a member of itself and not a member of itself". — TonesInDeepFreeze
. I am more concerned with what issues you solve with your beliefs. — Lionino
It seems to be a collection of semantic games — Lionino
The relative consistency of those theories indicates that it is not contradictory that a set is a member of itself and also a member of other sets. — TonesInDeepFreeze
Is it logically possible for a set to be both a member of itself and a member of other than itself? If it is a member of other than itself, then it is not a member of itself, is it? And if it is a member of itself, it is not a member of other than itself is it? — Philosopher19
And don't say to me something like "some set theories allow for this or that". I'm asking a basic logical question that has a basic and straight forward answer. There is no need to dance around anything. Just deal with the main issue at hand. — Philosopher19
I don't know anyone who has said that all others are ignorant. You are ignorant on the subject. That doesn't entail that others are ignorant on it. Indeed, there are people who critique classical set theory who are extremely knowledgeable about it. Critiques of set theory are quite fair game and bring profound insights into the subject. But those are knowledgeable, responsible and thoughtful critiques. And better yet, they are critiques that are followed up with actual mathematical alternatives to classical set theory. — TonesInDeepFreeze
Is it logically possible for a set to be both a member of itself and a member of other than itself? If it is a member of other than itself, then it is not a member of itself, is it? And if it is a member of itself, it is not a member of other than itself is it? — Philosopher19
He did it again! He completely skipped recognizing the refutation given him. — TonesInDeepFreeze
By the way, we don't need to use temporal phrases such as "at the same time". Set theory does not mention temporality.
Then the rest of your z's and v's is irrelevant if it is supposed to refute the proofs I gave. — TonesInDeepFreeze
I will just say this. That a set cannot be both a member of itself and a member of other than itself is the equivalent of saying that a shape cannot be both a square and a triangle (I have taken out the "at the same time" and the effect is still the same). — Philosopher19
In certain alternative set theories, there are sets that both members of themselves and of other sets. — TonesInDeepFreeze
We go in a circles, as it is with cranks. The crank makes false claims and terrible misunderstandings. Then the crank is corrected and their error is explained. Then the crank ignores all the corrections and just posts the false claims and misunderstanding again as if the corrections and explanations never existed. — TonesInDeepFreeze
There is no object called 'Infinity' in the sense you have been using it.
Here is a way to say what you want to say:
In mathematics, there are sets that are infinite but that have different cardinality from one another.
Better yet:
If x is infinite then there is a y that is infinite and y has greater cardinality than x. — TonesInDeepFreeze
There is no object called 'Infinity' in the sense you have been using it. — TonesInDeepFreeze
There is no x such that for all y, y is a member of x iff y is not a member of y. Proof: — TonesInDeepFreeze
the axiom schema of separation — TonesInDeepFreeze
'There exists a z such that for all y, y is a member of z' contradicts this instance of the axiom schema of separation: For all z, there is a x such that for all y, y is a member of x iff (y is a member of z and yis not a member of y). — TonesInDeepFreeze
We do NOT claim that from "after each natural number there is a next number" and "there is no greatest natural number" that we can infer that there is a set of all the natural numbers. Indeed such an inference IS a non sequitur. And every mathematician and logician knows it is a non sequitur. So, we recognize that to have a set with all the natural numbers we need an AXIOM for that, which is NOT an inference. — TonesInDeepFreeze
But from what I've seen of mathematicians, they either have no part for infinity, or they're using infinity wrongly. I believe they're doing the latter which leads to the former (which I think is why I have heard it said before that "maths is incomplete") — Philosopher19
It makes a real difference. By saying 'infinity' as a noun and then that there are different sizes of infinity is to picture an object that has different sizes. There is no such object in mathematics. — TonesInDeepFreeze
Good faith in posting a critique of mathematics would entail at least knowing something about it. — TonesInDeepFreeze
But from what I've seen of mathematicians, they either have no part for infinity, or they're using infinity wrong. I believe they're doing the latter which leads to the former (which I think is why I have heard it said before that "maths is incomplete") — Philosopher19
He still persists in mischaracterizing mathematics as claiming that there is an "Infinity" [capitalized, no less] that has different sizes — TonesInDeepFreeze
That is egregious intolerance — TonesInDeepFreeze
I guess this "something" is "space", right? Like a balloon ...
But this seems impossible since space is part of the universe itself; it cannot be larger than it. E.g. like the space around a balloon that is inflated ... — Alkis Piskas
Doesn't infinity mean endless? i.e. unreachable eternal continuation in concept? — Corvus
If it was reachable, then it wouldn't be infinity. Any set or size would be unknowable, if it were infinity. Therefore talking about different size, set or number of infinity, is it not a nonsense? — Corvus
Not 'infinity' as a noun, as if there is an object named 'infinity', but rather 'is infinite' as an adjective to name a property. — TonesInDeepFreeze
What you've seen is what you've allowed yourself to see, which is virtually nothing about the actual mathematics you've not even bothered looked up. — TonesInDeepFreeze
But from what I've seen of mathematicians, they either have no part for infinity, or they're using infinity wrong. I believe they're doing the latter which leads to the former (which I think is why I have heard it said before that "maths is incomplete") — Philosopher19
When it comes to the empirical application of the concept of infinity, it is indeed reasonable to think that it is fundamentally unverifiable whether something is infinite — DanCoimbra
I see what you mean. Well, the words "exist" and "existence" can be used in different ways. And it can be used strictly (substantially, concretely) and loosely (insubstantially, abstactly). And I guess the second form applies to what you say above. — Alkis Piskas
But doesn't an expanding universe mean that this process is infinite and thus the universe itself is limitless? It is not much different than if we consider the universe as being static, in which case it can also be infinite. — Alkis Piskas
As an analogy, consider looking at a dictionary and judging how truthfully the definitions represent how people are actually using the words which are defined there. — Metaphysician Undercover
It may well be the case that existence determines truth, like you say, but that's not relevant to the selection of mathematical axioms. — Metaphysician Undercover
The axioms do not give mathematicians rules for how to do things, because the mathematicians get to create and choose their own axioms. So the axioms simply provide a representation of what mathematicians are doing. Since they are descriptions, "truth" is to be found in how well the axioms represent what the mathematicians are actually doing — Metaphysician Undercover
How? — Lionino
But Euclidian triangles don't exist in nature. — Lionino
You cannot start counting 1,2,3,4,... ad infinitum and reach somewhere, anywhere. Infinity has neither a start or an end — Alkis Piskas
Then, counting (natural) numbers you can never reach infinity because that infility would be also a number, and infinity is not a real or natural number. — Alkis Piskas
A set is a collection of objects (elements, members). I'm not sure if we can talk about an infinite set — Alkis Piskas
All this raises questions about the infiniteness of the Universe, whether it started (created) from something or it always existed, etc. And, as I see it, since we don't have a proof that it is created from nothing, it must have always existed, even in the form of extremely high density and temperature, which at some point exploded (re: Big Bang), or in any other form. But I'm not the right person to talk about these things. — Alkis Piskas
First, imagine you have achieved immortality and are presented with two options: to receive $1 every day forever or $1 every year. Intuitively, you would choose $1 every day because, over the same infinite duration, you would accumulate more money. This illustrates that while both options extend to infinity in time, the rate at which you receive money differs, leading to a larger "size" of wealth in one scenario over the other. — punos
Now, let's consider a spatial analogy. Imagine two pipes, both of infinite length, but one has a diameter of 1 inch and the other has a diameter of 10 inches. Despite their lengths being equally infinite, the pipe with the larger diameter has a greater volume. This demonstrates that even with one dimension being infinite, other finite dimensions can contribute to a difference in "size" or capacity. — punos