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by thaumasiotes 1318 days ago
> "Two" is also just a name for the successor of 1. I could also call it "bob" and thus "two" would not be unique, but I don't see the point.

There is no point, because 2 is well defined.

That is also true of the ℶ numbers, but it is not true of the ℵ numbers. That's why, in that case, it's necessary to have multiple names for the same number.

> The fact is that the cardinal of countable numbers is a mathematical concept which has a name, and can be manipulated.

No, that's not a fact, that's what I'm saying.

The cardinality of the naturals is a mathematical concept. It is referred to as "the cardinality of the naturals", or by many similar phrases.

But it is not referred to by the name ℵ₀. ℵ₀ is a name that refers to a different concept, the cardinality of the ordinal number ω. The two cardinalities are equal, but ℵ₀ specifically refers to one of them, conceptually, rather than the other.

ℶ₀ refers to a different concept again. That's the one that is meant to be manipulable.