The other day I was talking to someone at work, and he told me that no one should judge another person’s belief or religion. In response, I said that if that were the case, then Hitler was justified in what he did. He answered that Hitler believed he was right, so to him it was right. Please comment on this.

A person must be careful when he tries to reduce his opponent’s position to absurdity or to deduce from the position an implication that even his opponent will not accept. We call this the ad hominem argument, that is, a logical ad hominem rather than an ad hominem of irrelevant personal attack. When used incorrectly, the tactic can backfire.

It is best to reduce an opponent’s position to logical absurdity rather than just cultural absurdity. You can bring out the implications of a position such that someone from a particular background or culture would consider it absurd and thus unacceptable, but this does not refute the position. It tells us something about the person and his culture, but the position itself is unharmed. Only something that is logically absurd is truly wrong, refuted, and indefensible.

If we confine the discussion to a narrow context, excluding biblical premises or any other moral standard, then there is nothing logically absurd in what Hitler did or in the position that what he did could be considered right. So if you press a position only to a point where it is culturally unacceptable, then the argument backfires when your opponent breaks with culture and accepts it anyway.

You must never rest your case on an ad hominem, or give the impression that you do. To rest on an ad hominem can mean that you really have no positive reason for your faith. Then, if you give the impression that you rest on an ad hominem and it backfires, your opponent will think that he has surprised you and that he now has the upper hand.

In preaching the gospel and defending the faith, it is insufficient to show only that you are less wrong. You must show that you are right, and that your opponent is wrong. Even an ad hominem that shows logical absurdity in your opponent can prove only that he is wrong. And an ad hominem that shows cultural absurdity, if it works on the opponent, can prove only that he is inconsistent. It does not even show that his basic position is mistaken.

When used carefully and correctly, an ad hominem can be an effective way to begin a conversation, to stun your opponent in debate, or sometimes even to refute a position (without necessarily proving the opposite). Perhaps the most important and useful purpose of an ad hominem is to drive the debate toward the deeper questions of metaphysics and epistemology. These are the purposes for which I would sometimes use ad hominem arguments, but I would insist that my own position does not depend on them, especially when the conclusions of these arguments do not demonstrate logical absurdity in my opponent, or when refuting his position this way does not prove my own.

Given your opponent’s point of view, his answer was correct, in the sense that it was consistent with what he said. Unless there is an absolute moral standard, there is no rational justification for condemning Hitler. So you cannot say that because we condemn Hitler, there must be an absolute standard – this reverses the correct order of reasoning. You might soften this and say that because we condemn Hitler, it implies that we believe in an absolute standard. But whether this is effective still depends on how your opponent responds. He might say that then we are wrong in having a standard, so that we should abandon it.

You might insist that, without an absolute standard, we cannot account for ethical principles. Your opponent could answer that we should therefore have no ethical principles. From here you can still win the debate, but you have already complicated matters too much. It is useless to argue by saying, “Unless X is true, you cannot account for Y,” unless X is really true, and unless it is really necessary to account for Y. So by complicating the debate, without proving or refuting anything, you have only delayed at least by one step the need to discuss the real questions, which concern metaphysics and epistemology.

Here is also where pseudo-presuppositionalism errs. It habitually demands the opponent to account for things that are inherently irrational, that cannot and should not be defended in the first place. Then it claims that the biblical worldview can account for them, but never succeeds in showing how. It further compounds the problem by making what is inherently irrational the very precondition for knowing the biblical worldview, thus also shutting itself out of it. So in the end it only sets up another school of irrationalism. In contrast, we acknowledge that the biblical worldview is perfectly rational, so that it excludes all things that are not. What we take away from the unbelievers, we do not embrace but throw away.