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>Philosophers have been trying and failing for millennia to come up with hard rules for ethics.

They've been trying to find one true/correct system of ethics, which is doomed to fail due to https://en.wikipedia.org/wiki/Regress_argument. What I'm talking about is not trying to find new systems, rather just formalising existing systems, so that they can be analysed more rigorously and checked for consistency. Much as for instance one can formalise and compare homotopy type theory and set theory as foundations for real analysis.

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Rudolf Carnap worked hard on formalizing ethics (and everything else) in the 20th century; the project was a total flop.

It turns out you can't formalize anything that doesn't have proofs -- in other words, it basically only works for what we'd call "mathematics" or "pure logic". You can't formalize literally anything else in philosophy, at all.

The regress argument has nothing to do with ethics in particular. It applies just as much to any non-proof area of study, including all of science, history, and even ordinary observations and recollections.

>It turns out you can't formalize anything that doesn't have proofs -- in other words, it basically only works for what we'd call "mathematics" or "pure logic". You can't formalize literally anything else in philosophy, at all.

What do you mean by "doesn't have proofs" here? It's demonstrably possible to develop a formalised philosophy: see Spinoza's Ethics for an example. It's impossible to prove that one formalisation is more "correct", but the same applies to mathematics, via Gödel's second incompleteness theorem.

>The regress argument has nothing to do with ethics in particular. It applies just as much to any non-proof area of study, including all of science, history, and even ordinary observations and recollections.

It also applies to maths in the form that a system cannot prove its own consistency. Yet that doesn't stop us formally analysing, comparing and making use of different mathematical systems.

> It turns out you can't formalize anything that doesn't have proofs -- in other words, it basically only works for what we'd call "mathematics" or "pure logic". You can't formalize literally anything else in philosophy, at all.

This couldn’t be further from the truth. There is a wealth of logics that have been developed and studied within philosophy, that aim to formalize various philosophical concepts. See modal logics, deontic logics, logics about knowledge and belief, and so on.

The notion of a "proof" is only meaningful in a formal context.

Logic, mathematics, computer science, proof theory... same thing. https://en.wikipedia.org/wiki/Proof_theory

We are eternally stuck interpreting all of our theories in the context of their meta-theoretic assumptions.

Not sure we’re talking about the same thing here. I was replying to your claim that nothing in philosophy (apart from mathematics) can be formalized. The role of logic is not to solve the metaphysical problem of infinite regress.

Logic itself is a formalism.

Subject to all the constraints of formal language theory/linguistics.

It fails to address the symbol-grounding problem.

https://en.wikipedia.org/wiki/Symbol_grounding_problem

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