To respond to the substance of your argument that being sufficient in any of rationality, philosophical competence, and metaphilosophical competence makes you sufficient in all of them:
sufficient metaphilosophical competence should imply broad philosophical competence
You could discover an algorithm for doing philosophy (implying great metaphilosophical competence) but not be able to execute it efficiently yourself.
since metaphilosophy is a kind of philosophy, sufficient philosophical competence should imply sufficient metaphilosophical competence
Philosophical competence could be a vector instead of a scalar, but I agree it’s more likely than not that sufficient philosophical competence implies sufficient metaphilosophical competence.
Sufficient philosophical competence would allow you to figure out what it means to act rationally, and cause you to act rationally.
I agree with the first part, but figuring out what rationality is does not imply being motivated to act rationally. (Imagine the The Blue-Minimizing Robot, plus a philosophy module connected to a speaker but not to anything else.)
Philosophy is just a special case where the data is our intuitions about what concepts should mean, the hypotheses are criteria/definitions that capture these intuitions, and the datapoints happen to be extremely sparse and noisy.
But where do those intuitions come from in the first place? Different people have different philosophically relevant intuitions, and having good intuitions seems to be an important part of philosophical competence, but is not implied (or at least not obviously implied) by rationality.
To respond to the substance of your argument that being sufficient in any of rationality, philosophical competence, and metaphilosophical competence makes you sufficient in all of them:
You could discover an algorithm for doing philosophy (implying great metaphilosophical competence) but not be able to execute it efficiently yourself.
Philosophical competence could be a vector instead of a scalar, but I agree it’s more likely than not that sufficient philosophical competence implies sufficient metaphilosophical competence.
I agree with the first part, but figuring out what rationality is does not imply being motivated to act rationally. (Imagine the The Blue-Minimizing Robot, plus a philosophy module connected to a speaker but not to anything else.)
But where do those intuitions come from in the first place? Different people have different philosophically relevant intuitions, and having good intuitions seems to be an important part of philosophical competence, but is not implied (or at least not obviously implied) by rationality.