Argumentation is the act or process of forming reasons and of drawing conclusions and applying them to a case in discussion. Christians are required to argue (1 Peter 3:15), so we should learn to do it well. When it comes to learning how to argue, you can find no better model than Jesus. (Which is why I co-wrote a book titled, How to Argue Like Jesus).

But you can also learn to argue well by learning how not to argue. On that subject, I’m somewhat of an expert. Over several decades I’ve argued a lot and, on the whole, made quite a mess of it. But while I have a woefully rudimentary knowledge about how to argue (a shameful admission considering I wrote a book on the subject), I’ve learned more than my share about how not to argue.

I plan to offer a set of heuristics on argumentation and persuasion. Heuristics are commonsense “rules of thumb” intended to increase the probability of solving some problem. The heuristics I offer aren’t derived from careful exegesis of rhetorical textbooks or from rule books on Oxford-style debating. These rules of thumb are merely useful tips I’ve learned from a long history of rhetorical mistake-making. I won’t take offense if you disagree. But I will try to persuade you that following these tips will make you more persuasive.

What Not to Do: Don’t appeal to folk fallacies in countering arguments.

Why Not to Do It: As a heuristic, “avoid folk fallacies” isn’t all that helpful until we answer the question, “What in the world is a ‘folk fallacy’?” The answer requires a bit of explanatory background (so bear with me, hopefully it’ll be worth the effort). But for now let’s think about our new heuristic as “avoid appealing to those rules of thumb known as “informal fallacies.’”

To understand what makes an informal fallacy a folk fallacy (and why we should avoid them) we should start by understanding what constitutes a fallacy.

In argumentation, fallacies prevent us from forming good arguments. A good argument is one whose conclusions follow from its premises; its conclusions are consequences of its premises. This is known as logical consequence. To maintain this chain of logical consequence — to ensure the conclusions follow from the premise — we need a truth-preserving structure, a way to keep the argument “valid.” A valid argument is one where if the premises are true, the conclusion must be true. The structure that best preserves the truth of an argument is a logically valid form.

For instance, we can express the logical form of a valid argument as “All A are B. All C are A. Therefore, All C are B.” This argument is formally valid, because every instance of arguments constructed using this scheme are valid. (A valid argument may also be sound or unsound, depending on whether the premises are true.)

What happens when you have an error in the logical form? Then you have a formal fallacy. These types of fallacies are not formal in the sense of formal attire like tuxedos but formal in that they affect the truth-preserving form of an argument. Since a formal fallacy messes up the logical consequence, it prevents an argument from being valid. (An argument with an invalid form can still be true, but it won’t be necessarily true.)

The beauty of formal arguments is that if you can get someone to agree on the truth of your argument’s premises then all you have to do is run it through a logical form that is valid and then they have to accept the truth of your conclusion. If they don’t then you can play the trump card that they are being illogical. (No one wants to be illogical.)

Formal arguments are appealing but it becomes difficult to judge their validity in the the hustle and bustle of real world discussions. Most arguments we have are detailed and complex. Because they are mixed up with a lot of rhetorical detritus, it’s often difficult to feed these arguments through the conveyor belt of a logically valid form in order to get an attractively wrapped conclusion that everyone has to agree on.

This difficulty of assessing formal arguments explains the appeal of informal fallacies. Informal fallacies don’t affect the form, and thus may or may not affect the validity of the argument. Yet people tend to treat informal logical fallacies as if they held the same status as a formal fallacies. The result is that many people think they can score points in an argument by throwing down an informal fallacy as a trump card. They think they are playing an ace of spades when they are throwing down a deuce of diamonds.

Let’s look at an example of a commonly cited informal fallacy, the “No true Scotsman.” The term, first coined by the late British philosopher Antony Flew, refers to how when faced with a counterexample to a universal claim, some people will modify the subject of the assertion to exclude the specific case. That sounds complicated, so let’s look at an easily digestible example:

Person A: “No Scotsman puts sugar on his porridge.”

Person B: “I am Scottish, and I put sugar on my porridge.”

Person A: “Well, no true Scotsman puts sugar on his porridge.”

The implication is that by adding an additional requirement, Person A has committed a fallacy of reasoning. But this simply isn’t true. There could be valid reasons to believe the additional requirement is part of the definitional nature of the original claim. For instance, if all Scotsman have a genetic condition that makes them deathly allergic to sugar, then someone who regularly puts sugar on their porridge (and doesn’t die) is likely not a Scotsman at all.

Many informal fallacies (I would say most of them) are either conditional fallacies (i.e., they depend on the circumstances of the argument) or are not fallacies at all. Informal fallacies are a form of what philosopher Brandon Watson calls “philosophical folklore” or “folk fallacies”:

Among the many things worth studying, one of the most interesting is what I call ‘philosophical folklore’. Folklore, of course, consists of micro-traditions passed down within communities as part of the ordinary ways of life of the people in those communities. . . .

Of all subjects in philosophy, I think informal logic tends to provide the richest veins of philosophical folklore. Reasoning and evaluating reasoning are things everyone has to do. Formal logic tends to get too technical to be widespread. Informal logic, on the other hand, is almost purely folkloric in nature. Unsystematic and messy, it consists chiefly of rules of thumb, folk classifications, proverbs, slogans, and the like.

To say that informal fallacies are folk fallacies does not mean they are worthless. As with any widely accepted rules of thumb, informal fallacies are likely to be carrying at least a germ of practical wisdom. For this reason they can sometimes even be useful in our task of learning “how not to argue” since they provide practical examples of what patterns of argumentation to avoid.

In future entries we’ll consider why to avoid calling out people for specific folk fallacies, such as claiming someone has committed the informal fallacy of ad hominem. But for now it will suffice to point out three reasons why we should avoid claiming someone has committed an informal fallacy:

1) Such claims are never persuasive – You will never win an argument (especially one on the Internet) by telling people they are committing an informal fallacy. If you are debating someone who is also enthralled with folk fallacies, they may change their tactics to avoid being told they are committing a particular fallacy. But you are unlikely to persuade them or anyone else that disagrees with you that they are actually committing an error in reason. People may cite informal fallacies, but they rarely believe informal fallacies are truly fallacies of reasoning when applied to themselves.

2) You’re probably using them wrong — Almost ten years ago I got into a heated debate with a notoriously rude and prickly academic philosophy professor. He insulted my intelligence, so I accused him of committing an ad hominem fallacy. He claimed he did no such thing and I accused him of not understanding logic. In hindsight, I realize he was right. His insulting me had nothing to do with his argument or his reasoning. Sometimes being called an idiot by a jerk is just an insult and not a fallacy. (By the way, if your instinct is to turn to Wikipedia or some other reference to figure out which informal fallacy someone is committing – don’t waste your time. See #1.)

3) Such claims sidetrack the debate – Will pointing out the fallacy help prove the truth of your premises or conclusion? If not, then you are providing a distraction from the purpose of your argument.

What to Do Instead: For the reasons listed above, spending time debating whether someone has committed a particular folk fallacy is always a waste time. Fortunately, there is a profoundly powerful tool that can replace almost every appeal to informal fallacies: the clarifying question.

Consider our example above about Scotsmen, sugar, and porridge. What happens if we point out our interlocutor is committing the “No True Scotsman” fallacy? Most likely we’ll have to explain to them what the fallacy is, why it’s an error in reasoning, and how they’ve committed it. That’s two premises and a conclusion that we now have to argue for that have nothing to do with defending our original argument.

Instead, we could have saved ourselves a lot of trouble by merely asking, “Can you clarify what you mean by ‘true Scotsman’”? The onus is then on them to explain why a certain requirement is necessary to be a Scotsman. Even if you don’t agree with their answer, you’ll have a better understanding of the position they are arguing for.

Any time you suspect someone is committing an informal fallacy use a clarifying question. Instead of saying someone is resorting to ad hominem, ask them why they think that character trait affects the validity of the argument. Instead of telling someone their statement is a non sequitur, ask them to explain how their conclusion follows from their stated premises. This method works because it forces the person to think for themselves and untangle their own reasoning. This method works because everyone has an easier time persuading themselves than they do being persuaded by others.

The drawback to this method is that you won’t get to display your vast knowledge of Latinate informal fallacies (or at least your ability to look them up on Wikipedia). But the upside is that by replacing appeals to folk fallacies with a simple clarifying question, your persuasive abilities will instantly increase.