Inconsistency: assuming opposite truths simultaneously.
This may take many different forms. Most common with unbelievers is the double standard. This is especially common with Muslims, who argue about what Christians have done in Islamic countries (whether the Crusades or Colonialism or The West), but they won’t even consider, let alone acknowledge what early Muslims did in the Middle East and Europe (Spain). They will insist that the Jewish people shouldn’t have returned to Israel, but at the same time they still want to go back to Spain.
Like arbitrariness, inconsistency also has several subcategories.
- (i) Logical fallacies: These are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points. An example is the common phrase: no real scientist believes in creation; this is a fallacy known as “poisoning the well” (sometimes called “no true scotsman”). It aims to ridicule and discredit in advance any evidence we might bring to the discussion. In this example, every time you bring a scientist who believes in creation you would be told “he is not a real scientist”. There are many fallacies, and I would suggest anyone interested in apologetics to read up on the different forms they can take. One book my children use is “The Fallacy Detective” and it’s a great introduction; if you want something more advanced, there is “Logically Fallacious” by Bo Bennett.(ii) Absurdity: A statement which inevitably leads to a ridiculous, absurd, or impractical conclusion. This must be addressed with the method of reductio ad absurdum, following the premise through to its logical conclusion and showing the absurdity of such a conclusion. The opposite method can also be used, to prove a statement by showing that if it were not true, the result would be absurd or impossible. This can be a very useful tool when talking with various types of unbelievers, such as when you are talking with a person who believes that morality is a personal choice. Showing them that his position makes genocide, gang rape, or cannibalism a personal choice is to reduce his choice to absurdity.(iii) Behavioural inconsistencies: These might be simply a sign of hypocrisy, but it might be much more than that, such as in the case of a moral relativist who is outraged about the war in Afghanistan.(iv) Presuppositional tensions: This is when someone holds two or more presuppositions that don’t work together. For example a Muslim, who insists on using convincing reasoning, at the same time holding a belief, which says that Islam is to be introduced to non-Muslims and if they don’t accept it, they should become subject to it or die. How can they reconcile their request for rational argument with the Quranic instruction to "[f]ight those who do not believe in God, nor in the Last Day, nor forbid what God and His Messenger have forbidden, nor abide by the religion of truth - from among those who received the Scripture - until they pay the due tax, willingly or unwillingly” (Qur’an 9:29)? What if we told Muslims we were going to operate according to their own rule, so we would “fight those who do not believe in Jesus Christ, nor in the Last Day, nor forbid what the Lord Jesus Christ and His apostles have forbidden, nor abide by the religion of truth - from among those who received the Quran - until they pay the due tax, willingly or unwillingly;” is a Muslim going to be OK with that? We have to press on and highlight this tension, or cognitive dissonance. This is a sound illustration of why we must learn how to listen carefully to what is presupposed by unbelievers.