10 Types of Logical and Argumentative Fallacies

Many of these phrases are often used consistently in work conversations, which can lead to relationship problems.

Everyone at some point in their life has faced debates with people who use different types of logical and argumentative fallacies.

Perhaps without realizing it, it happens with our relatives, friends, and acquaintances. This is even more common in classrooms, and often at work.

What are logical and argumentative fallacies?

They’re arguments that are used to support an idea that someone is presenting, which, at first, seem to be logical, but as they continue presenting their ideas, we realize that they have no basis in truth.

In order to realize that the arguments a person uses to justify themselves “logically” in any given discussion topic are invalid, it’s necessary to pay careful attention and analyze the arguments presented in the debate.

Being able to detect when a person is using any of the types of logical and argumentative fallacies is a skill that, with the passage of time and experience you’ll be able to perfect. It’s a very good idea that, right from the beginning of the debate, you take careful note of each argument. In this way, apart from identifying their fallacies, you’ll learn to better justify your ideas too.

The 10 types of logical and argumentative fallacies

Although the list of logical and argumentative fallacies is quite extensive, we’re going to bring you a list with the 10 most common ones, which are divided into two large groups: non-formal and formal. Recognizing them will make it easier for you to spot them in other people’s arguments, and to identify when someone is violating their line of reasoning.

Non-formal fallacies

Non-formal fallacies are those that don’t allow us to reach a conclusion, regardless of whether the arguments used are true or not. In them, the arguments presented are usually gone over and over, and there’s never a conclusion that allows the person to understand something specific from them.

1. “Ad ignorantiam” fallacy

This attempt to justify the accuracy of an idea or thought is expressed using the simple fact that there’s no way to prove that it’s false. These arguments seek to validate the existence of something that no one has seen, something for which there’s no evidence in favor, but neither is there any against. Because of this, it’s neither true nor false.

2. “Ad verecundiam” fallacy

The fallacies ad verecundiam or fallacies of authority try to link the accuracy of an argument with an authority that can give weight to what they are expressing.

An example of this fallacy could be “the Ministry of Health has said that coronavirus vaccines have tracking chips.” And, obviously, even though the Ministry is cited as the source of this information, it doesn’t mean that it’s true. In this case, it’s clear that it’s false.

3. “Ad hominem” fallacy

The “ad hominem” fallacy is intended to take away the truth or accuracy of an argument, idea, or conclusion by highlighting the negative characteristics of the source (a person, company or something similar) of the argument. It doesn’t have the objective of denying the presented idea with solid arguments, but, rather, it criticizes or distorts the person or groups that defend the idea.

4. “Post hoc ergo propter hoc”

In this type of fallacy, it takes for granted that, if the argument we’re referring to is based on an unrelated fact, then it’s valid, and much more so if it opens the doors to another outcome. This is because there’s no more information to verify it.

5. Straw man fallacy

The straw man fallacy refers to the caricature or misrepresentation of an opponent’s argument. It’s considered to be extremely dishonest because it seeks to attack or refute the other person without a valid or reasonable argument.

An example of this is when two senators from different parties face each other. One requests an increase in the health budget and the other, in order to bring down his arguments, attacks the proposal by saying “look who’s saying this – the senator whose party is only interested in war.”

6. “Ad consequentiam” argument

This is a type of fallacy that tries to make the idea valid based on what a person can infer from it. If an idea is exposed to a person who may agree with the theory, this implies that the person will take the argument as valid. However, for the person who sees this as wrong, it won’t be valid.

7. Hasty generalizations

This type of fallacy includes a general argument that can’t be substantiated by sufficient information. That is, if you’re trying to base your argument on something that isn’t well enough developed or proven, then you’re making a hasty generalization.

This is more evident if you add to this some illogical assumptions, stereotypes, or exaggerations that lead to racist or sexist statements.

Formal fallacies

Fallacies are formal when there’s an inaccurate or invalid relationship among the ideas you present. Here, we aren’t referring to anything false as such in the arguments, but to a problem of coherence between them.

So, we can say here that the arguments we present may be true, but the veracity fails due to the inconsistency between your arguments.

8. Denial of antecedent

This type of fallacy has two parts, one that conditions the other, and so denying one will deny the other. For example, “I will always love you if you marry me.” Here, the only conclusion is that if you don’t get married then they won’t always love you.

9. Undistributed middle term

In this type of fallacy, the middle term is reasoning that’s formed by two or more premises and a logical conclusion that you infer from them. And this is what leads us to link two propositions that don’t lead us to an exact conclusion.

10. Affirmation of the consequence

Here, a conditioner is also included, but, in this case, a second element is affirmed and an erroneous inference is made, such as: “If I approve it partially, I’ll have some wine. He had some wine, I approved it partially”.

Other types of fallacies

There are other types of fallacies that don’t belong to the two previous groups. We’ll now give you two examples of this type of fallacy:

Sunk cost fallacy

The sunk cost fallacy refers to a refusal to face a reality that becomes threatening; it usually occurs when we don’t want to accept a loss.

When you have undertaken a project that ends up going wrong, but which you refuse to give up, it becomes a fallacy when you insist on doing this, simply because you know how much it has cost you. All this without taking into account that you may have to invest much more, all in order not to have to assume the loss.

Circular fallacy

The circular fallacy, which is also known as “petitio principi” occurs when we present an argument that’s repeated over and over again. However, there’s no clear or well-argued conclusion.

For example, in the phrase “what is written in the Bible is true“, the one who expounds this idea may not give a solid argument, beyond simply assuming that everything written there is true because it’s there.

Populist fallacy

In our current era, which is characterized by the democratization of information thanks to the web, it’s common to be lead into this fallacy. Also known as the “ad populum” argument, this fallacy refers to an idea that is validated or invalidated because many people agree with it.

“It isn’t bad to drink alcohol every day” could be a populist fallacy if many people claim that it’s true. Moreover, they may back this up by saying that they have drunk a lot and nothing serious has ever happened to them. This is a type of fallacy that is used a lot by some companies to spread the word in favor of their products.

Are you ready to identify logical and argumentative fallacies?

It’s likely that you face debates on a daily basis in which one or more types of logical and argumentative fallacies are used and you may not have realized it. However, now you know the most common ones, and you have examples that can help you identify them.

Knowing these fallacies allows you to organize ideas and define solid arguments, based on demonstrable facts that are difficult to refute. Beyond making others look bad by their use of fallacies, the important thing is that you know how to present your arguments without the need to resort to these methods.