> If they were so patently ridiculous, I doubt many philosophers would believe them.
> If you have a solid argument aganist moral realism
The key counter argument here, as to why the philosophy domain is so messed up, is because of motivated reasoning.
If you could get a PhD in the topic of "does God exist?" I can bet that most of the people with a "does God exist" PhD would say "yes" and they would come up with increasingly complicated and obfuscatory reasons for why that is the case.
Because why else would you go and get that degree in the first place? What, you would spend 4 years of your life, just to get to the answer of "no"?
And then they would say that they are the experts in the topic of God existing, therefore they are right.
A similar thing applies to philosophy. It's mostly motivated reasoning. People twist themselves into convoluted pretzels, all because they really want to believe that the universe proves their morals correct.
That's a much more tempting conclusion, than the boring one of "well, I guess everyone just has axioms, and that's that. We can't re-concile them. Oh well!".
So of course they get to the conclusion that morals exist. Because that conclusion means something. It means that you are right on the most tempting conclusion of truth and aught statements, and math/the universe makes it so!
You can wield that conclusion as a weapon. Of course people want that.
And even better, it can't be tested, in the real world, by definition! How convenient.
And then they say they are correct, because they are the self proclaimed experts on the topic, and if you cannot parse their ever more complicated, or ever more obfuscated arguments, well I guess you are a science denier like everyone else who disagrees with the "experts".
As in, it is literally almost the most perfect example of motivated reasoning. Untestable. Convoluted. Powerful. And by definition the basis for what people should do.
And philosophers just happened to come to the "convenient" conclusion.