Is there a moral obligation to pay any attention to moral theorizing?
If there is, then a morality is already operating at the level of cognition and the entire history of moral theorizing is superfluous.
If there's not, then all moral theorizing is itself morally baseless.
Has anyone in the entire history of philosophy ever addressed this issue?
I don't know of a single instance of the supervisory criteria or prior standards of moral theorizing even being mentioned much less addressed prior to the 20th Century.
Wilbur Marshall Urban started in on this at Yale beginning in the 1920s, in pointing out the morality of thought running in tandem with logic and general rationality (Beyond Realism and Idealism), behind all theorizing (the obligation to be rational, the value of inquiry, truth valued over falsity, and so on), but never got into the actual prior standards problem of it. Nor in that sense did Plato probe the "man is the measure" issue. Ditto for Augustine and Aquinas concerning the standards for analyzing eternal truths and convertibles. Barry Stroud identified some of those issues in his monumental book on Hume but somehow could see the staggering consequences and so didn't run with it.
Neo-Thomist Urban got the ball rolling, then Catholic philosopher Joseph Boyle turned it into a science in the late 1960s (at the behest of the great Germain Grisez), followed by secular scholars Stephen Bartlett and Peter Suber (of open access fame) who published two books on the subject.
But in general both academic philosophy and Christianity in general are still sitting on their asses about reflexivity---especially metatheoretic criteria---while their respective Rome's continue to burn.
Earlier this year Pinker panicked and resorted to self-referential refutation against the postmodernist self-contradiction mongers in an essay on Skeptic Mag's site. Apparently he realizes that Christianity is so close to being culturally dead philosophically that it isn't jacked enough to call the bluffs of atheism's own neo-positivist scientific realism and cognitively moralistic crypto-theism that hides behind the intellectual curtain of all reason thumping.
