A fallacy is a part of an argument. Specifically, it is a part that is able to be shown to have a logical problem or flaw. Once that flaw is demonstrated, the whole argument fails. (When this is so, the argument is said to be “fallacious.”)
You would be astonished at how frequently fallacies occur in arguments, from the most casual and conversational to the most articulate, meticulously word-smithed presentation. They are as common as the rain.
When a fallacy occurs, it is usually a subtle, and can be hard to detect at first; this is often because more than one fallacy occurs at the same time, and one masks the other. Fallacies come in the form of matters of relevance, vague or ambiguous use of words or ideas, matters of correlation or cause, or exploiting some sort of emotional element in the listener.
A good (and very common) example of a fallacy is the Ad Hominem fallacy. There are actually several different forms of an Ad Hominem (which is Latin, meaning “to the person”), but they all amount to something along the same lines: when you cannot strongly attack the argument itself, attack the person doing the arguing.
For example: in the discussions surrounding the issue of women as deacons/deaconesses, something the “pro” side (in other words, they were for some form of diaconal service being open to women) would often say is, “The reason the PCA’s Book of Church Order is the way it is can be traced back to the reactionary tendencies of the PCA’s founders.”
(Mea Culpa: I’ve said some form of this statement before.)
Let me first point out how this is an Ad Hominem fallacy: rather than addressing the argument-- namely, that the Book of Church Order as written prohibits any ordination of women to church office-- the response attacks the arguer. In this case, it means either, “The writers of the BCO were wrong because they were reactionaries,” or, “If you agree with the BCO, then you are wrong because, since the writers of the BCO were reactionaries, so are you.”
Neither of these is relevant to the question of whether the BCO is correct in its interpretation and application of Scripture when it comes to women in diaconal service. Therefore, claiming that the writers were reactionaries has no real bearing on the soundness of the argument.
How do you deal with an Ad Hominem fallacy when one is thrown at you? There are several strategies:
- Take the higher ground: ignore the fallacy and stick to the facts and real arguments. Give other listeners the benefit of the doubt in being able to recognize the fallacious quality of the argument. (Best when the Ad Hominem is obvious and blatant.)
- Address it briefly: suggest that there is no reason to get distracted by name-calling, and request that you stick to the subject at hand instead of getting distracted by irrelevant opinions. (Best when the audience is neutral about whether the Ad Hominem is true, and/or when the Ad Hominem is based on a highly opinionated perspective rather than something more factually-based.)
- Force them to work it out: ask them probing questions about their claim, requiring them to explain the direct relevance of what they have said and gradually exposing their argument as a fallacy. (Best when the audience is favorable toward the fallacious position.)