This Solum post deals with a new paper available on SSRN dealing with Mackie's Ethics: Inventing Right and Wrong, which I read during my undergraduate days as a philosophy major at the University. Indeed, it is on the shelf somewhere in this room.
I once wrote a note to a professor (a great man, now deceased) of the Philosophy Department, which note said essentially this: having learned from Mackie that we need morality on account of our limited sympathies, I am hoping that as this is my last semester your sympathies are not so limited, because I have no moral claim to your acceptance of my paper at this late date. I slipped the paper and the note under his closed door in Old Cabell Hall and lingered in the hall long enough to hear him laugh - I told you he was great.
(And you thought I thought John Mackie was the tight end for the Colts back in the Unitas days.)