Desiring Good with Free Will
Well i guess there are two things going on. One do they exist, and two how would they be defined if they do exist.
I would say there are dangers that have been well written about in rejecting objective moral value.
I'm not however saying that the dangers prove moral value. The dangers are not about truth as much as they are about what is good for us to know.
I would imagine your not a fan of CS Lewis, but I feel like he explains the dangers much better than I ever could in "The Abolition of Man". He is only talking about the reaches of science and not arguing for religion. The warning at the end CS Lewis gives is that we have to be careful explaining these intuitions away like the intuition that some things (for instance rape) are just wrong no matter what,
He says that we don't want to go on explaining everything away and that eventually when we have explained humanity away we won't be human any longer. Hence the abolition of man.
The analogy which I love and I'm paraphrasing:
The point of looking through the window is to to see the garden on the other side. What good would it be if the garden were also transparent. And if we are able to see through all things, that would be the same as to not see at all..