Incredulity about Moral Realism

The famous professor Allan Bloom says in his most famous passage,

There is one thing a professor can be absolutely certain of: almost every student entering the university believes, or says he believes, that truth is relative. If this belief is put to the test, one can count on the students’ reaction: they will be uncomprehending. (The Closing of the American Mind, p. 25)

This semester (as an undergrad philosophy instructor) I have been privileged to put Mr. Bloom’s belief to the test. I am sad to report that, at least with regard to moral truth, it is absolutely true.

What's more, it is clear that most of these students have never been challenged in their relativism; nor have they even questioned it themselves. Hence the general bafflement at my apparent "absolutism." For example, upon gently pushing the class to consider the notion that at least some moral propositions (i.e. Torturing babies for fun is morally wrong) are objectively true, I was met with incredulous stares, followed by the exasperated objection: "But then there would be absolutes!" "Well, yes, I guess you could put it that way, though I prefer to use the word 'objective' as opposed to 'absolute'." More incredulous stares.

Almost equally as shocking was their uniform and quite obviously fallacious argument for relativism:

People in different cultures have totally different morals than we do. They think their morals are right, and we think ours our right [although apparently we don't]. So morality is relative.

My response went something like this:

First, I'm not at all confident that beliefs about morality fundamentally differ from culture to culture. But let's just grant that for the sake of argument and look at your reasoning. Your argument seems to pivot on the principle that if people radically disagree about x, then x is neither true nor false but relative to some individual or culture or society or .... But people radically disagree about all sorts of stuff, even scientific stuff. Consider the debate between the Heliocentrists and the Geocentrists. The Helios and the Geos radically disagreed about the nature of the universe. Was there no truth of the matter? Was it true for the Geos that the earth was the center of the universe and true for the Helios that it was not? No! Then why should we think that mere disagreement about moral matters somehow entails relativism?

The few, the timid, the objectivists seemed to have gained courage at this point and began weighing in. I was very thankful for them. But for the most part my counterattack was ignored and met with a repetition of the fallacious argument and supplemented with some stories about how there are cannibalistic tribes in Africa and Alaska. I rephrased my point...to no avail, and round and round we went.