Re: Which axiom prohibits this kind of construction?



On Sep 30, 2:11 am, Aatu Koskensilta <aatu.koskensi...@xxxxxx> wrote:
Virgil <Vir...@xxxxxxxxx> writes:
But the set of all subsets of an infinite set like the set of naturals
has no explicit well-ordering, and while it may be theoretically
well-orderable given the axiom of choice, it supposed to  be impossible
to actually /construct/ one.

Enkai'sworry was that in presence of foundation the levels of the
cumulative hierarchy might not be well-ordered, that there might be an
infinite descending sequence of levels of the cumulative hierarchy.

--
Aatu Koskensilta (aatu.koskensi...@xxxxxx)

"Wovon man nicht sprechen kann, darüber muss man schweigen"
 - Ludwig Wittgenstein, Tractatus Logico-Philosophicus

Yes, I'm pretty sure I meant that. So wouldn't this be forbidden,
since z = [y] = [[x]] = [[[w]]] = ... and so on infinitely?
.



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