Relativists often make the claim that no one has the truth and that we should therefore be open-minded and "tolerant." Francis Beckwith presents us with an excellent dialogue (based loosely on a real-life exchange) which demonstrates why the relativist position is itself, ironically, close-minded and intolerant. This particular exchange takes place between a student and teacher but can easily be adapted to other real-life situations you may find yourself in.
Teacher: "Welcome, students. This is the first day of class, and so I want to lay down some ground rules. First, because no one has the truth about morality, you should be open-minded to the opinions of your fellow students."
Student: "If nobody has the truth, isn't that a good reason for me not to listen to my fellow students? After all, if nobody has the truth, why should I waste my time listening to other people and their opinions? What's the point? Only if somebody has the truth does it make sense to be open-minded. Don't you agree?"
Teacher: "No, I don't. Are you claiming to know the truth? Isn't that a bit arrogant and dogmatic?"
Student: "Not at all. Rather I think it's dogmatic, as well as arrogant, to assert that no single person on earth knows the truth. After all, have you met every person in the world and quizzed these people exhaustively? If not, how can you make such a claim? Also, I believe it is actually the opposite of arrogance to say that I will alter my opinions to fit the truth whenever and wherever I find it. And if I happen to think that I have good reason to believe I do know the truth and would like to share it with you, why wouldn't you listen to me? Why would you automatically discredit my opinion before it is even uttered? I thought we were supposed to listen to everyone's opinion."
Teacher: "This should prove to be an interesting semester."
At this point, another student blurts out, "Ain't that the truth," provoking the class to laughter.
This dialogue can be found in at least two books by Beckwith: Defending Life: A Moral and Legal Case Against Abortion Choice (p. 13), and Relativism: Feet Firmly Planted in Mid-Air (p. 74, co-authored by Greg Koukl).