I quoted Robert P. George this morning because I want to comment on the argument he discusses. Here it is (in essence):
1. People disagree about moral matters.
Therefore,
2. There is no objective moral truth.
Let us call this "the argument from disagreement." George says, rightly, that it is fallacious: "the absence of objective moral truth does not follow from the existence of disagreement" (page 1390). In other words, it is logically possible for people to disagree about moral matters even if there is objective moral truth. Some philosophers refute the argument by analogy. They replace "moral" with "factual." It's true that people (even scientists) disagree about factual matters, but false that there is no objective factual truth. Since no valid argument, by definition, has true premises and a false conclusion, the argument is invalid; and since it has the same form as the original argument, and since validity is a function only of form (as opposed to substance), the original argument is invalid, too.
Note that even if George and these other philosophers are right, they haven't proved that there is objective moral truth. All they have shown is that this particular argument against moral objectivism is a bad one. An invalid argument can have a true conclusion, after all. Here is an invalid argument with a true conclusion:
1. The Pittsburgh Steelers won the 2009 Super Bowl.
Therefore,
2. Barack Obama is the 44th president of the United States.
Here's what I want to discuss. Why do moral objectivists such as George focus on the weakest possible argument against moral objectivism? It was once thought that theism could be refuted by the mere existence of evil. This was the burden of J. L. Mackie's famous essay "Evil and Omnipotence" (1955). Mackie argued that the propositions "God exists" and "evil exists" are inconsistent. (Actually, he argued that the propositions are inconsistent when conjoined with certain "quasi-logical rules," but let's ignore that complication.) If evil exists, therefore, which it clearly does, then God doesn't. It wasn't long before atheists abandoned this argument, for it became clear to them, largely as a result of Alvin Plantinga's work, that God and evil are compatible. Thus, the existence of evil does not disprove the existence of God.
Atheists didn't give up; they merely revised their strategy. Instead of trying to show that evil makes God impossible, they tried to show that evil makes God improbable. In other words, they turned from deduction to induction. Theists replied to these arguments as well, which generated a third atheistic strategy. (Thrust and parry, thrust and parry.) Instead of arguing that any evil at all makes God improbable, atheists tried to show that certain types of evil (horrendous evil, for example, or gratuitous evil) make God improbable. Once again, theists replied to the argument. Some atheists have now retreated to abduction. They argue that the best explanation of the data (which include the various evils we find in the world) is that there is no god.
Notice the progression. "God is impossible, given evil" became "God is improbable, given evil," which became "God is improbable, given certain types of evil," which became "The best explanation of the data is that there is no God."
Moral subjectivists can, and in my opinion should, adopt the same strategy as atheists. Early on, perhaps, it was argued that because people disagree about moral matters, there is no objective moral truth; but, as George and many others have shown, this is invalid. Clearly, there can be disagreements about a particular matter even if there is a fact of the matter about that matter. Humans are fallible.
The moral subjectivist then turns to the second argument, to wit: Moral disagreement, while compatible with objective moral truth, makes it improbable that there is objective moral truth. The moral objectivist can make the same reply here as the theist did. At this point, the moral subjectivist can focus on a subset of moral disagreements, those involving experts. The argument is that even people who devote their entire lives to studying morality do not agree on moral matters. An even stronger version of this argument says that for more than 2,000 years, some of the most brilliant people in the world (e.g., Aristotle, Aquinas, Hume, Kant, Bentham, Russell, Ross, and Anscombe) have tried to discover objective moral truth. Alas, there is as much moral disagreement today as there was 100, 500, 1,000, or 2,000 years ago, if not vastly more. The disagreement is at every level: metaethics, normative ethical theory, practical ethics. Surely, the moral subjectivist says, this makes it highly improbable that there is objective moral truth. Wouldn't it have been discovered by now, if there were? Wouldn't we have reached a consensus on moral matters, or something approaching it? Instead, we have radical dissensus.
As a last resort, the moral subjectivist, like the atheist, can use abduction. He or she argues that the best explanation of the sharp disagreements among moral "experts" (as well as among ordinary people) is that there is no objective moral truth. What we have, as in the case of theism and atheism, are rival hypotheses. The moral objectivist says that the best explanation of the data is that there is objective moral truth. Disagreement is explained away as the product of ignorance, inattention, irrationality, defiance, or (in the case of theistic moral objectivists such as George) sinfulness. The moral subjectivist says that the best explanation of the data is that there is no objective moral truth. Morality is invented, not discovered.
Let me summarize. Theists acknowledge that there is evil. Moral objectivists acknowledge that there is moral disagreement. The question is what, if anything, follows from these facts. There are four stages of argument:
1. The atheist says that evil makes God impossible. The moral subjectivist says that moral disagreement makes objective moral truth impossible.
2. The atheist says that evil makes God improbable. The moral subjectivist says that moral disagreement makes objective moral truth improbable.
3. The atheist says that gratuitous/horrendous evil makes God improbable. The moral subjectivist says that intractable moral disagreement by experts makes objective moral truth improbable.
4. The atheist says that the best explanation of the data is that God does not exist. The moral subjectivist says that the best explanation of the data is that there is no objective moral truth.
Moving from 1 to 4, the arguments become stronger, and therefore harder to rebut. Atheists no longer make the first argument, and even the second has fallen into disfavor. Why do moral objectivists such as George reply only to the first argument against moral objectivism? This is like beating up a two-year-old child. Yes, you can do it, but what have you accomplished?
