You have probably heard some in our culture say something like the following: “1) Since people disagree about moral truths that means we should tolerate other people’s world views. 2) If you don’t like a behavior don’t do it, but don’t impose your morality on others. 3) Besides, there is no such thing as absolute truth.”
All three statements are self-refuting. The first statement says we should tolerate others’ world views. This statement, therefore, sets itself up to be our moral standard. We are required to adhere to this moral imperative while simultaneously rejecting moral imperatives. Thus, it refutes itself. The second statement is no better. It imposes the view that we should not impose our values on another. The third statement is simple enough. It declares to be true that there is no such thing as truth.
Dissecting the first statement a little further, we encounter the problems of disagreement and tolerance. Disagreement does not lead to relativism. “If the mere fact of disagreement were sufficient to conclude that objective norms do not exist, we would then have to acknowledge that there is no objectively correct position on such issues as slavery, genocide, and child molestation…,” but virtually everyone agrees these acts are evil. Further, “The relativist has set down a principle—disagreement means there is no truth—that unravels his own case.” For, we would have to accept this principle as a truth. Thus, it self-refutes. Tolerance does not provide a sanctuary for the moral relativist either, because it actually supports objective morality. “If everyone ought to be tolerant, then tolerance is an objective moral norm. Therefore, moral relativism is false.” Relativism, thus, becomes intolerant because it rejects, or is intolerant of, moral truths.
The second statement provides no advantage to the moral relativist either. Here, the moral relativist is attempting to turn a moral claim into a preference claim; “I ought” into “I like.” Take abortion for example. A pro-choice interlocutor might say, “If you don’t like abortion, then don’t have one.” This statement is designed is to reduce the abortion debate to a preference claim. Because human life begins at conception, however, this would be like saying, “If you don’t like murder, then don’t kill any innocent persons.” Thus, this logic removes the “ought” part of the action (e.g. “You ought not to murder”) and reduces it to mere preference (e.g. “It’s preferred that you not murder”). By making morality subjective, murder is no longer wrong, it’s just not preferred. The problem here is that preferences are easily changed. Murder could be right or wrong based on society’s feeling about the matter. Objective moral truths, however, are applicable to all people at all times, because all human beings have the same nature. Since human nature never changes, moral laws never change.
For more on moral relativism, read Catholic Catechism paragraphs 1749-1756, 1776-1794.
All quotes from: Francis J. Beckwith, Why I Am Not A Moral Relativist, at: https://appearedtoblogly.files.wordpress.com/2011/05/beckwith-francis-22why-i-am-not-a-moral-relativist22.pdf.