An anonymous commenter asked this question on a philosophy blog. To my mind, it reveals exactly why philosophy is producing so few stars these days:
How do you define "correct" moral theory? Is there something more to it than internal consistency?
People love to make philosophy into an inextricable muddle so they have an "educated" excuse to keep doing what they wanted to do anyway, which was please themselves (a moral "fapping").
Correct moral theory is that which corresponds to reality.
Isn't that obvious? No, it's not: the textbook says moral theories are theories that are internally consistent, and it's all arbitrary, because with our heaters, TVs, cars, computers, video games and iStranger masturbation devices, reality is far, far away.