by sarchertech | 2025-10-19 20:47:44+00:00
>Humans are unsound, so Gödel doesn’t apply.

As Penrose points out, the claim is conditional. Take a recursively axiomatized theory T for which we have Pi_1 soundness level warrant, i.e., we have reason to think its Pi_1 theorems are true in the standard model N for the arithmetical cases we care about. Then we can see (again: in N) that G_T is true while T cannot prove it.

That gives principled grounds to adopt Pi_1 reflection or otherwise step to a stronger T'. No infallibility claim about people is require. This mirrors the ordinary kind of warrant mathematicians use when they adopt new axioms after scrutiny and debate.

>A proof checker plus brute-force search can do Gödel reasoning, so a robot can do it.

A checker plus search enumerates exactly the theorems of whatever fixed system it’s tied to. You can also script computable progressions that iterate reflection or consistency along recursive ordinal notations in the Turing/Feferman style. That’s still a single computable progression determined in advance. It isn’t that such progressions don’t exist, but that our justified acceptance is not a priori bounded by any one fixed computable progression.

The mechanist reply here is an existence thesis: there exists some computable procedure whose output matches everything humans could in principle come to rightly endorse for arithmetic. If that’s your view, give the existence argument. If instead you propose a specific computable progression P that we could in principle ratify as Pi_1 sound in toto, Gödel/reflection immediately pushes past P. If you say we can’t justifiably ratify P as a whole, you’ve conceded the point that no single precommitted computable scheme captures the moving boundary of what we’re warranted to accept.

>Gödel didn’t show transcendence.

In the narrow sense above, Gödel shows how to go beyond any accepted, fixed rule set once we have Pi_1 soundness level warrant for it. That is exactly the move at issue. Note the scope: inside a system you can’t adopt “if provable then true” without collapse by Löb. Outside, adopting restricted Pi_1 reflection is the justified step. If you want to reject the move, reject the warrant. Deny that we sometimes justifiably regard a given fragment of T as Pi_1 sound for the cases at hand. That’s an objection about epistemic warrant, not a logic gotcha.

>Busy Beaver shows limits, so case closed.

Busy Beaver actually helps here. It yields concrete Sigma_1 statements that can be independent of strong base theories, illustrating that warrant-driven extensions are sometimes needed to settle specific instances.

Either sometimes we do have adequate Pi_1 level meta warrant for a theory T on the arithmetical claims we care about. In which case we can recognize G_T as true in N and rightly move to T', ensuring our recognitions outrun that fixed T. Or deny such warrant altogether, in which case you haven’t refuted the conditional. You’ve just changed the target to a weaker notion of “what we can recognize.” The “humans are unsound” line doesn’t touch that conditional, and “just use a checker plus search” doesn’t answer the challenge unless you can support the existence of a single computable theory or precommitted progression that captures everything we could in principle come to rightly accept for arithmetic.