On Mon, Jan 13, 2025 at 5:58 PM Jesse Mazer <laserma...@gmail.com> wrote:

*> Doesn't Godel's theorem only apply to systems whose output can be mapped
> to judgments about the truth-value of propositions in first-order
> arithmetic?*


*That's Godel's Completeness Theorem which concerns First Order Logic
(FOL), not to be confused with his better-known Incompleteness Theorems
which are concerned with Second Order Logic (SOL). FOL can do stuff like;
Socrates is a man, all men are mortal, therefore Socrates is mortal.
Unfortunately FOL is pretty weak, if something can be proven in FOL then it
can also be proven in SOL, but the reverse is not necessarily true. In FOL
you can not define things like "finite" or "continuous", you can't use
mathematical induction and you can't even do arithmetic. For those things
you need SOL, but it's incomplete, and it can't prove its own consistency.*

*John K Clark    See what's on my new list at  Extropolis
<https://groups.google.com/g/extropolis>*
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