I should add: when discussing morality, I think it’s important to give the anti-realist’s position some consideration (which doesn’t seem to happen in the post above). See Joshua Greene’s The Terrible, Horrible, No Good, Very Bad Truth About Morality and What To Do About It, and J.L. Mackie’s Ethics: Inventing Right and Wrong.
I should add: when discussing morality, I think it’s important to give the anti-realist’s position some consideration (which doesn’t seem to happen in the post above). See Joshua Greene’s The Terrible, Horrible, No Good, Very Bad Truth About Morality and What To Do About It, and J.L. Mackie’s Ethics: Inventing Right and Wrong.