edit: but that is a nice paper you linked to. thank you.
edit: but that is a nice paper you linked to. thank you.
What about where set theory interplays with model theory? Would it surprise you to hear that the dizzying towers of infinities that can be spoken of in ZF can be modeled by a merely countable universe? What about a computer program (albeit an impractical one) that decides whether sentences about the natural numbers with successor are true or false, whose existence is discovered by proving that large uncountable models are isomorphic?
To be clear, it's okay to be bored by this stuff. I tend to get bored pretty quickly when people start talking about systems of DEs or eigenvectors, or really much of anything that looks too much like calculus, and I'm not about to apologize for my apathy for those things. But most of the above stuff tends catch the attention of even the humanities types, who are easily deterred by most mathematical topics.
Out of curiosity, I might ask whether you're similarly bored by computability theory or complexity theory, which leverage many of the same tools as those used in set theory (mappings as preorders, diagonal arguments, etc), but add computable enumerability/uniformity/syntacticity requirements to the mix.
But if mathematicians’ convention is that they will refer to ZFC when writing their proofs about something else I am interested in, I am willing to humor them, and keep my caveats to myself.
I’m reasonably well convinced that most models mathematicians can make in the context of ZFC which have any real-world implications (e.g. accurately simulate some physical phenomenon) could be alternately proved under some more restrictive set of axioms, just sometimes with a lot more hassle.
Why?
But it doesn’t really matter what I think. This is not a fight I care about. It’s like arguing with Buddhists about the nature of suffering or something.
YMMV.
[1] https://math.stackexchange.com/questions/315399/how-does-zfc...
What do you find hand-wavy or circular about it?
Can you specify which absurd implications you're referring to?
Not trying to argue, just genuinely curious.