Not surprisingly, the relativists were not slow in responding. One individual posted the presumably crushing comment that, "there may very well be 'absolutes', but due to our human condition, it is likely impossible for any of us to truly know them."
There are some interesting issues raised here. The comment, "there may very well be 'absolutes', but due to our human condition, it is likely impossible for any of us to truly know them" brings in the question as to whether it is truly possible to know anything — even whether it is possible to know that you don't know, which is also knowledge and thus truth. Taking as a starting point the assumption that we can know something, even if the extent of our knowledge is that we know nothing other than that we know nothing, we can resolve the question by applying a little common sense.
When we examine this statement, we realize that it is precisely because of our "human condition" that we are able through the use of reason to discern absolutes and apply them in various ways to meet human wants and needs — especially the human need to develop more fully as persons by acquiring and developing virtue, that is, by conforming ourselves ever more closely to our own nature. Humanity is made in the image and likeness of God; our human nature is a "reflection" of Divine Nature. Human nature thus incorporates an "analogously complete" capacity to acquire and develop that virtue of which God is the fullness, that is, absolute good, truth, love, beauty, justice, and so on by definition, that is, by our substantial nature or essence; our capacity to acquire and develop virtue is what defines us as human. To deny that is to deny our humanity.
The argument is fairly straightforward. First, we must understand that the first principle of reason — of existence itself — is that nothing can both "be" and "not be" at the same time. Whatever is, is, while whatever is not, is not. Whatever is in the category of "A" is by that fact excluded from the category of "Not-A." This is the "law (or principle) of contradiction," or (less frequently, but perhaps more accurately) the "law (or principle) of non-contradiction."
Second, we have to understand that the claim that there are no absolutes, or that there may be absolutes, but that it is not possible to know what they are, is the same as saying that it is not possible to know whether a thing is true or untrue, good or evil, right or wrong — or (more concisely) that it is impossible to know right from wrong. Lacking an absolute standard, however dimly perceived by the use of human reason, against which to measure something, it becomes impossible to measure that thing.
(We can reject as meaningless the statement that there may be absolutes, but that it may or probably not be possible to know them. "May not be" implies "may be" as an equally valid conclusion. It is thus simply a way of avoiding committing yourself one way or another; a way of asserting the unknowability of absolutes without actually saying so.)
Third, given that it is possible to perceive or discern absolutes, whether or not "through a glass darkly," we necessarily conclude that it is possible to "know" — that is, to distinguish right from wrong, or truth from untruth. Every injustice implies a standard of justice against which the injustice is measured and found wanting. Every wrong implies a right, every untruth implies a truth.
For example, the prohibition in the Decalogue, "Thou shalt not steal" necessarily implies private property as an absolute, that is, as pertaining to the natural moral law. If private property were not based on an absolute right of every human being to be an owner, then theft could not possibly be wrong — yet every society that has ever existed has proclaimed theft to be wrong. Different societies may define theft differently, even incorrectly, and thus apply the natural right of property differently or erroneously, but the basic principle, that private property is part of the natural moral law, remains unchanged and unchangeable.
Thus, "knowing" (participating in some measure in God's Intellect by acquiring and developing virtue) — distinguishing right from wrong, truth from untruth — necessarily implies absolutes, such as truth, love, justice, and so on. The concepts of good and evil, right and wrong, necessarily imply the existence of absolutes from which we derive our idea of right and wrong. As Mortimer Adler explained,
The reason why I say that everyone, as a matter of common sense, understands truth and falsity is that everyone knows how to tell a lie. Every one of us has told lies on one occasion or another, and everyone understands the difference between telling a lie and telling the truth. (Mortimer J. Adler, "Man the Knower," Aristotle for Everybody. New York: Macmillan Publishing Company, Inc., 1978, 151-152.)Fourth and finally, the declaration that it is impossible to discern the existence of absolutes and come to know them is contradictory. That is, you cannot claim that it is impossible to know absolutes . . . and state it absolutely. It defies reason; it implies that something can both "be" and "not be" at the same time; you cannot state absolutely that there are no absolutes or that knowing them is impossible. Nor can you claim that someone is wrong for maintaining that it is possible to know right from wrong . . . for, if you cannot tell the difference between right and wrong, how do you know that someone else is wrong on anything — and how do you know that you are right?
"This way lies madness." Asserting that there are no absolutes or that it is impossible to know them are statements in the same category as, "Everything I say is a lie," or, "If God can do anything, then He can make a weight so heavy He cannot lift it." These are word games and simplistic logic puzzles for children, not reasoning adults. The only rational course of action is to realize that there is a contradiction somewhere in the statement, identify it, and reject the entire statement as inconsistent with reality, that is, with nature. We otherwise run the risk, as Rommen pointed out, of descending into pure moral relativism, positivism, even, ultimately, nihilism. Insanity becomes the only escape.