On my reading of the Euthyphro, what is supposed to be wrong with the idea that the pious is what the gods love is that as even Euthyphro knows the gods love the pious because it is pious. (The famous dilemma is largely a rhetorical flourish. It’s clear to Socrates and Euthyphro which horn to take.)
It seems to me that little is gained when one says that the pious is what it is appropriate for the gods to love. For it is just as clear that the reason that it is appropriate for the gods to love pious actions is that the pious actions are pious.
Once we see this, we see that a similar objection can be levied against many appropriateness views, such as Strawson’s view that the blameworthy is what makes appropriate certain reactive attitudes. For it is clear that these reactive attitudes are appropriate precisely because the person is blameworthy.
There might be some things that are to be accounted for in terms of appropriate responses. But I can’t think of any other than perhaps pure social constructions like money.
