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the mathematical discipline that applies mathematical methods to the study of mathematical theories themselves.

4 votes

Intuitive and/or philosophical explanation for set theory paradoxes

The history of axiomatic set theory did not proceed in the way that you suggest here. Zermelo, for example, was motivated to form his axiomatic system primarily in order to give a careful proof of hi …
Timothy Chow's user avatar
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44 votes

The enigmatic complexity of number theory

What references, especially books, have been devoted to specifically addressing the source of the deep roots of the diversity and complexity of number theory? To a first approximation, I would sa …
6 votes

Are there natural examples of mathematical statements which follow from consistency statements?

The short answer is no. Con(T) is a very weak assumption and it is asking a lot for it to have interesting mathematical consequences. A slightly less ambitious question is whether "ZFC + the consist …
Timothy Chow's user avatar
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13 votes
Accepted

A meta-mathematical question related to Hilbert tenth problem

There's a general "trick" for handling all issues of this sort. Take any mathematical theorem that a platonist regards as meaningful. Formalize it as a formal theorem T in ZFC. The formalist will n …
Timothy Chow's user avatar
  • 82.6k
40 votes

Top-down mathematics, or "Where it all begins"

One approach, mentioned by Pace Nielsen in the comments, is to start with what I call strict formalism. The only substantive assumption required for strict formalism is that you are capable of recogni …
Timothy Chow's user avatar
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24 votes

Are there any good nonconstructive "existential metatheorems"?

Harvey Friedman has an example of a finite statement (that's actually "finite" and not "finitary," i.e., $\Pi_0^0$ rather than $\Pi^0_1$) that has a proof, using large cardinal axioms, that is no more …
23 votes
Accepted

What sorts of extra axioms might we add to ZFC to compute higher Busy Beaver numbers?

There's a certain confusion underlying your question, which Andreas Blass's answer is trying to point out. Let me see if I can explain it in different words. You say, “the negation of Con(ZFC) proves …
Timothy Chow's user avatar
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7 votes

Formal proof of Con(ZFC) => Con(ZFC + not CH) in ZFC

You have almost answered your own question; it seems that the only part you are confused about is whether "the reflection principle operates outside ZFC." One must, as always, distinguish between the …
Timothy Chow's user avatar
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29 votes
Accepted

What is known about the relationship between Fermat's last theorem and Peano Arithmetic?

The main reference for this topic is Angus Macintyre's appendix to Chapter 1 ("The Impact of Gödel's Incompleteness Theorems on Mathematics") of Kurt Gödel and the Foundations of Mathematics: Horizon …
Timothy Chow's user avatar
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2 votes

How can you formalize the metamathematics conventionally used to state Godel’s theorem?

I believe that what you're looking for is a development of Gödel's theorem in what we might call "the language of syntax" rather than "the language of arithmetic." The closest thing I'm aware of to w …
Timothy Chow's user avatar
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