I’ve commented on this once before here, but thought I’d give it another shot. I’m developing this argument for students so figured I’d get objections here first. At the end, I connect it back to the point of this blog (or part of it).

Many people seem to think that whether a particular act is wrong cannot be determined objectively. Many, indeed, seem to think it is a purely subjective matter: if I think the act is wrong, it is wrong for me; if you think its not, its not for you. Others think it is a cultural matter: our society thinks the act is wrong so it is wrong for us; yours does not, so it is not for you. Obviously, I think this is misguided. Indeed, I think we should be seeking truth, where that should be read as “objective truth.” In fact, I am not sure how to understand claims like this: “well, its true for me, but not for you” (whether the “it” is a moral claim, an aesthetic claim, or a scientific claim). I can certainly understand the claim that “I believe its true and you do not.” There we simply have differing opinions. But the truth of a claim does not depend on my opinion, your opinion, or even our opinion.
(Caveat: Of course, the claim “In my opinion, X” very clearly depends on my opinion, but it doesn’t depend on my opinion about the claim.)

Consider the claim “God exists and is omni-beneficent.” Some people believe this claim. Others do not. Does the fact that they have different opinions matter? Before answering that question, notice that we don’t seem to hear debate about the presupposition behind the question: it is a fact that there are different opinions. We take this to be objectively true. That is, we do not say “well, its true for some people that different people believe there is a God and false for other people that different people believe there is a God.” Such a statement would ordinarily be met with incredulity. In fact, if the statement were accepted—it never is, so far as I can tell—we would face the same question at the next level: is it an objective fact that “its true for some people that different people believe there is a God and false for other people that different people believe there is a God”? or is that claim subjective so that

its true for some people that “its true for some people that different people believe there is a God and false for other people that different people believe there is a God” and false for other people that “its true for some people that different people believe there is a God and false for other people that different people believe there is a God.”

The mind boggles at such a question. Of course, the issue gets even crazier if we ask if that claim is itself objectively true or not. Apparently, there are some claims that we all agree are objectively true. The obvious claim here that we all take to be objectively true is that people have different opinions about the existence of God.

Now return to the question that began the last paragraph: does the fact—and I now assume we all agree it is a fact—that people have different opinions about whether God exists matter to the objectivity (or lack thereof) of the claim that God exists? Let me cheat here and simply switch the burden of proof: why would it matter that there is disagreement? Of course, it matters that there is disagreement about God’s existence for very longstanding political reasons: some that believe in God wish not to tolerate atheists, perhaps some atheists wish not to tolerate believers, and clearly believers in different descriptions of God (which go along with different religions) wish not to tolerate believers in other descriptions of God. The narrow question here, though, is this: what difference could it make to the existence of an all-good God that some believe he (or she or it) exists and some do not? I think put that way, the answer is obvious: none whatsoever. It is either the case that God exists or it is the case that he does not. One of those is the objective truth. If God exists, atheists are wrong; if he does not, then theists are wrong. There is an objective fact of the matter even if we do not know what that objective truth is. Our lack of knowledge of the truth has no effect on the truth whatsoever.

If you’ve come this far and agree with me (even if you think some or all of what I said was obvious): why should morality (and in particular given the point of this blog–political morality) be any different? There are (fairly famous) arguments about this (e.g., from J.L. Mackie) that I never found persuasive and that others have argued against.