The 20 most important types of informal fallacies

A summary of the most commonly used types of informal fallacies in argumentation.

Everyone wants to be right. When we hold an idea in our innermost being, it is because we consider it to be the best of all possible ideas on a given issue, and we rarely give in to abandoning it without a fight first.

And that is why, when we give ourselves to the heat of the dialectical battle, we often make use of persuasive strategies, we often make use of persuasion strategies that break with formal logic; or we fall victim to the tricks of the trade.Or we fall victim to the trickery of others in order to take our opinion to their own territory (and sometimes without realizing it).

We know this type of logical juggling, which very often obviates logic and relegates it to a second order of importance, as fallacies. Sometimes, such fallacies are cognitive biases that harm the user more than others.

In this article we will deal specifically with informal fallacies.. Knowing them is essential to develop sufficient competence with our words to emerge victorious from debates, as well as to protect ourselves from the traps that our mind (or other people) can occasionally set for us.

What are informal fallacies?

Informal fallacies are reasoning in which premises are used that in appearance could be logical, but that in reality hide an error in their own structure (the arguments are biased in their approach or allude to irrationality). On some occasions they have a sequence that at a formal level is flawless, so they are not easy to recognize. The aim of the present text is to shed light on this matter, and to provide the necessary basis for identifying them in ourselves or in others.

Types of informal fallacies

We will now look at the 20 most important informal fallacies, as well as what each of them consists of. In order to facilitate their full understanding, we will also review specific examples.

1. Ad hominem

The ad hominem fallacy alludes directly to the person who makes an argument, but does not at any time consider the veracity or logic of what he is saying. The aim, in such a case, is to discredit the interlocutor or belittle his opinion based on "supposed" undesirable qualities, which undermine the strengths of his persuasive effort. For example: "if you are not a student at the university you are totally ignorant, and you have no right to give your opinion on this matter".

2. Ad baculum

The structure of an argument is sustained in an illogical way, resorting to imposition, threat or violence in order to persuade others to carry out an action or assume an attitude. to carry out an action or assume an attitude as their own. The content of such messages is unfounded in any way, and usually occurs in the context of a vertical or asymmetrical relationship (from the one who has authority to the one who does not). For example: "this is done this way because I said so".

3. Ad verecundiam

It is affirmed that a certain thing is true for the sole reason that the one who says it has a position of authority or is an expert on the matter in question.

The prestige of the source is the only reason given to validate an argument, without considering the fact that people may make mistakes (or other types of biases) despite having in-depth knowledge. Sometimes it is also claimed that something is true because it has been published in the media. For example: "that should be true, because they said it on TV".

4. Ad populum

The general belief on the subject under discussion is used to infer, from it, that the position held on it is correct or true. From this fallacy it is inferred that the popular consensus undoubtedly points to the correctnessTherefore, the direction in which others hold the opinion must be held up as the standard from which to orient one's own view of things. For example: "if this song is at the top of the charts, it is because it must be good and worth listening to".

5. Ad ignorantiam

Although the possibility of falsifying any hypothesis is a necessary characteristic for it to be considered in the field of science, this fallacy points out that the inability to demonstrate that something is wrong implies that it must be true. Whoever makes use of it does not consider it important to demonstrate the certainty of what he is affirming, but rather that the interlocutor proves its falsity.. For example: "I have a lion in the garage, and if not, prove to me that I am inventing it".

6. Ad antiquitatem

Traditions are for many people the basic guide to guide themselves in life and in their decisions on how to proceed in the face of daily uncertainty. Thus, what is passed down intergenerationally stands as the most basic rule, and the reason why something should be right or wrong. People who make use of this fallacy say that if a way of "doing things" has been useful for a long time, it will continue to be useful in the present and in the future.. For example: "this is so because it has been so all my life".

7. Ad novitatem

This fallacy can be considered a mirror of the previous one. In this sense, the veracity of any argument will be supported by alluding to its novelty or to the fact that it opposes or to the fact that it is opposed to what was once considered differently. Those who use it believe that the passage of time always leads to improvement, so that anything that has recently emerged will replace what has been done by tradition. For example: "today's technology is so advanced that today's movies are much better than those of twenty years ago".

8. Post hoc ergo propter hoc

This fallacy is based on the misinterpretation of contiguity, in the sense that whatever happens before an event must be its reason. Although it is true that the laws of cause and effect would require the temporal (and physical) proximity of the one and the other, not everything that happens in the vicinity of some event will be directly related to it, not everything that happens in the proximity of some event will be directly related to it.. For example: "they all shouted at the moment when the teacher entered the classroom, so that was the reason why they did it". It has also received the name of coincidental correlation.

9. Equivocality, ambiguity or antanaclasis

Polysemous words, or words that have multiple meanings, are used in order to provide a reason for their meaning.The purpose is to offer a reasoning whose processing leads the subject who might receive it to very ambiguous interpretations. On some occasions it is even possible that the connotations that arise from this are so discrepant that the intention is to manipulate the listener by "twisting" the rich semantics of a language. For example: "the end of life is only death itself" (understanding "end" as "purpose" or as "end").

10. Straw man

This fallacy consists of taking the argument of the person with whom one interacts to its ultimate consequences, forcing him to assume the most extreme position possible and distancing him from moderation. In this way it is possible for a well-considered reasoning to be blurred and deformed, facilitating much simpler counterarguments.

This fallacy also involves the misrepresentation of the original purposeuntil it ends up becoming different and difficult to defend. For example: "if you say that all people are equal, and murderers are after all people, then you are like all murderers".

11. Affirmation of the consequent

Every event can be divided into its causes and its consequences, that is, into antecedents and consequents. Sometimes an event may have more than one consequence and, moreover, when the latter occurs, it is not necessary that it has been preceded by a single cause. This process leads to conclusions that may be true, but which do not explore the totality of the options that could be involved.. For example: "When it rains, the ground gets wet. Since this ground is wet, it can be said that it has rained with certainty".

12. Negation of the antecedent

This case is the opposite of the previous one. As in the former, it is necessary to break down a fact into its causes and consequences. After that, a cause would be treated as the "absolute value" for the implied consequence, omitting in this act any additional explanatory factor for the consequent.

For example: "the person who works gets whatever he may desire. If you don't work, then you will never achieve it" (although you could achieve it through other means, such as chance, or by changing your goals to ones where work is not as relevant).

13. Hasty generalization

This fallacy implies that, from a series of isolated personal experiences (which are not representative of reality), the generalization of a much more complex phenomenon is carried out. It is a mechanism through which a fact that is too complicated to be fully and absolutely apprehended is cognitively simplified, and through which very often unfair stereotypes are born for those who carry them. For example: "I once went to the doctor and he made a mistake with my diagnosis, and they are all inept".

14. Claim of principle

This fallacy implies the articulation of premises that, by their very formulation, approve a series of assumptions that have not been validated in reality. And this is so because, by accepting their content, other aspects that have not been corroborated are accepted in a secondary way.

In this way, if we agree with the original reasoning, we will be approving others without really realizing it.. For example: "I always tell the truth" (from which it will be deduced, without solid evidence, that I never lie).

15. Gambler's fallacy

This fallacy distorts the real laws of probability by attending to events in the past that really have no relevance.. It is used, above all, in matters related to chance and has been systematically proven in those who suffer from pathological gambling. It can be a problem when it encourages them to persist in the behavior that is leading them to financial ruin. For example: "when tossing a coin, both heads and tails have up to a 50% probability of appearing. I've already done it nine times and every time it's come up heads, so it's more likely that the next time it will come up tails".

16. Ad nauseam

The ad nauseam fallacy consists of repeating the same idea enough times to make it real for the interlocutor.. It is based on the premise that "when a lie is told over and over again it ends up becoming the truth". It is a strategy widely used in the advertising sector, which aims to strengthen consumer confidence by reiterating the supposed advantages of a product or service in the various media. For example: "our toothpaste is the most effective toothpaste for the prevention of cavities" (repeated in different channels and in multiple time slots).

17. Ad misericordiam

This informal fallacy resorts to pity or pity in order to reinforce the appropriateness of what is being sought to be achieved.. It involves a search for reason, or interpersonal persuasion, appealing to the emotions of the interlocutor and his or her empathy with our situation. Emotions play a relevant role here, since they are manipulated by obviating the most basic logic. For example: "please pass my exam, you don't know how many days I have spent without sleep...".

18. Ad consequentiam

This fallacy suggests that, if the consequences derived from a premise are negative, it cannot be true. Thus, the arguments are stripped of their truthfulness because, if they were accepted, one would thereby assume something that is unpleasant or even catastrophic. or even catastrophic. As can be seen, it is very close to denial, and has a very important emotional substratum. For example: "climate change is a hoax, because if it were true, in just a few centuries the planet would collapse".

19. False dilemma

This fallacy aims to reduce a multiplicity of possible options to choose from to only two alternatives, often mutually exclusive. This creates an artificial dilemma in which the person is forced not only to choose any option among the few offered, but also to accept without further reflection the path that others have traced for him/her. For example: "either you are with me or you are against me".

20. Fallacy ad crumenam and ad lazarum

These fallacies suppose the attribution of truth to the argument by the fact that the one who uses it is rich (ad crumenam) or poor (ad lazarum). (ad crumenam) or poor (ad lazarum). It is similar to the cognitive winner-loser bias, a well-known phenomenon in Social Psychology that explains how people position themselves in favor of an individual because they are in a situation of privilege or disadvantage in a particular competitive context (especially in politics). Thus, it focuses on resources, or the lack of them, as a criterion from which to recognize the goodness of speeches. For example: "if Bill Gates says it, it must be true".

Bibliographical references:

• Cummings, L. (2014). Informal Fallacies as Cognitive Heuristics in Public Health Reasoning. Informal Logic, 34, 1 - 37.
• Hitchcock, D. (1989). Informal Fallacies. Teaching Philosophy, 12, 49 - 51.