Part of the reason for that misunderstanding may be because many atheists do in fact espouse the kind of relativist view that my critic finds objectionable. But the main problem is the over-simplification that is common in popular discussions and writings on this topic. Most people seem to think there are only two main positions one can take: absolutism/objectivism, which states that there are moral principles that are true for everyone at all times, and relativism/subjectivism, which roughly says that what's right for one person may not be right for another. What's worse, some atheists appear to associate the absolutist view with religion (in effect implying that if one adopts such a position, it is only because of one's religious beliefs), and as a result insist on relativism. And of course, the religious more often than not criticize atheism on the grounds that it is incompatible with objective values, and thus can only lead to relativism.
In addition to all this, the terminology involved isn't used in a consistent way even by philosophers. There are specific views which everyone basically agrees on the meaning of (e.g., non-cognitivism, emotivism, intuitionism), but some of the broader terms are definitely used in more than one way — and none more so than “subjectivism.” No wonder, then, that there is so much confusion.
Before explaining how subjectivism (according to most philosophers who call themselves subjectivists) is different from relativism, let me state some claims that a subjectivist can agree with (and that I in fact agree with):
“Every society that practiced slavery was wrong to do so.”
“The fact that most people in certain societies accepted slavery as permissible did not make it so, not even in those societies.”
“Anyone in a society in which slavery is practiced should oppose it.”
I don't think I can make it any clearer than that. Subjectivism should not be criticized on the grounds that every society that has practiced slavery was wrong to do so. And the reason is simple: the theory is not incompatible with the claim that it is always wrong to own another human being.
The difference between relativism and subjectivism
There are two types of moral relativism, the individual type and the group type. Often, people use “relativism” to mean only the latter, though that's also commonly called “cultural relativism.” But it's probably easier to understand the basic idea behind relativism if we start with the individual variety.
Basically, individual relativism is the view that when someone says, e.g., “x is wrong,” what they are saying is “I disapprove of x.” Thus, if I say slavery is wrong, but plantation-owner Sam says it is right, we can both be saying something true. For what I am doing, in effect, is reporting the fact that I disapprove of slavery, and what he is doing is reporting the fact that he approves of it. It follows that we are both correct!
Group relativism is exactly like this, except relative to societies instead of individuals. Thus, if I say human sacrifice is wrong, I am only saying that, in modern-day America (at least), human sacrifice is frowned upon, whereas if Zahatopolc the Inca says it's right, he is only saying that in his society it's allowed. Thus, once again, we can both be right.
One problem many have with this view is that it apparently makes it impossible to criticize other cultures. But in fact, many relativists endorse this consequence, defending it as the only really tolerant attitude. (Some, when they make this claim, even appear to treat toleration as a moral absolute.)
A subjectivist disagrees. According to subjectivism, moral statements don't state facts about the world (not even about what one or one's society believes). Rather, such statements express one's feelings about moral matters. So, if you say human sacrifice is wrong, you are not reporting what you or those in your group believe. You are expressing your disapproval. And there's no reason to claim that this disapproval doesn't apply to what others, including those in other cultures, believe or practice. That's why as a subjectivist, one can say slavery is wrong, period.
Note: There are many who confuse relativism with the idea that moral principles have exceptions. So if I state as a moral principle that (say) stealing is wrong, someone might object that in certain situations it is perfectly justified. For example, if the only way to save the life of someone who's been bitten by a venomous snake is by stealing some anti-venom, then you should do so. But that's not relativism. Non-relativists are perfectly willing to concede that moral principles have exceptions. Even killing an innocent person can be justified in some cases. All this means is that to correctly state a moral absolute, one would have to qualify the hell out of it. And because that's impractical, we state close approximations instead.
Subjectivism vs. objectivism
Moral objectivism is usually defined as the view that there are moral facts that do not depend on what anyone thinks, and which therefore are universal. It follows that for an objectivist, when someone makes a correct moral statement, they are not only expressing their view, they are also saying something true about reality. Objectivists therefore feel that something crucial is missing in the subjectivist view of things.
However, I can't see what's so important about there being independent moral facts that exist in addition to our moral commitments. When I say slavery is wrong, I'm expressing something I feel very strongly. I would not feel any different about it were I to find out that it is also a fact that slavery is wrong. It wouldn't make me oppose slavery even more.
Maybe objectivists also feel that on their view, it is possible to demonstrate what is really right and wrong (whereas on subjectivism that's obviously ruled out, since there isn't a “really” right or wrong, only how people feel about things). But as everyone should know, that's easier said than done. No one's come up with a theory of ethics that commands universal agreement, or anything close to it.
Lastly, objectivists of course assume that the particular moral views they themselves hold are the factually correct ones. But since people disagree over morality, it follows that if objectivism is true, most objectivists have a bunch of false moral beliefs. You may think slavery is wrong, but those who defend it based on what's in the Bible could be right. A subjectivist at least cannot have that problem. I disapprove of the Bible's acceptance of slavery, and that's that.
For all these reasons (and a few others), I don't see a problem with upholding subjectivism in ethics. It is not a view that in any way diminishes the importance of morality.
[Originally published at Debunking Christianity]