J. L. Mackie

Ethics: Inventing Right and Wrong opens by stating that there are no objective moral values, and then spends the book explaining why people nonetheless talk as though there are. Mackie called it an error theory: moral claims genuinely assert something about the world and every one of them is false. The two arguments are relativity, that moral codes vary with the societies holding them, and queerness, that objective values would be metaphysically unlike anything else we know of. He also wrote The Miracle of Theism, still among the most cited philosophical cases against belief in God. Australian by origin, he taught at Oxford, and died in 1981.