The 14 types of logical and argumentative fallacies

Arguments and reasoning contradictory to logic: how to identify them?

Philosophy and psychology are related to each other in many ways, among other things because both deal in one way or another with the world of thought and ideas.

One of these points of union between the two disciplines is related to logical and argumentative fallacies. logical and argumentative fallacies, concepts used to refer to the validity (or lack thereof) of the conclusions reached in a dialogue or debate. Let us take a closer look at what they are and what the main types of fallacies are.

What are fallacies?

A fallacy is a line of reasoning that, despite resembling a valid argument, is not valid..

It is, therefore, a line of reasoning that is erroneous, and the inferences presented as a product of these cannot be accepted. Regardless of whether the conclusion reached through a fallacy is true or not (it could be true by pure chance), the process by which it is reached is flawed, because it violates at least one logical rule.

Fallacies and psychology

In the history of psychology there has almost always been a tendency to overestimate our ability to think rationally, being subject to logical rules and being coherent in our way of acting and arguing.

With the exception of certain psychological currents such as the psychoanalytic one founded by Sigmund Freud, it has been taken for granted that adult and healthy human beings act according to a series of motives and reasoning that can be easily expressed textually and that normally fall within the framework of rationality. Cases in which someone behaved irrationally were interpreted either as a sign of weakness or as an example in which the person does not know how to identify the real reasons behind his or her actions.

It has been in recent decades that the idea of the idea has begun to be accepted that irrational behavior is at the center of our lives, that rationality is the exception, that rationality is the exception.that rationality is the exception, and not the other way around. However, there is a reality that has already been giving us a clue as to the extent to which we are driven by emotions and impulses that are little or not at all rational. This fact is that we have had to develop a kind of catalog of fallacies to try to make them carry little weight in our daily lives.

The world of fallacies belongs more to the world of philosophy and epistemology than to that of psychology, but while philosophy studies the fallacies themselves, psychology can investigate the way in which they are used. Seeing the extent to which false arguments are present in the speeches of individuals and organizations gives us an idea of the way in which the thinking behind them more or less adheres to the paradigm of rationality.

The main types of fallacies

The list of fallacies is very long and there are possibly some of them that have not yet been discovered because they exist in very minority or little-studied cultures. However, there are some that are more common than others, so we will to know the main types of fallacies can serve as a reference to be able to detect violations in the line of reasoning where they occur. wherever they occur.

Below you can see a compilation of the most well-known fallacies. Since there is no single way to classify them in order to create a system of types of fallacies, in this case they are classified according to their belonging to two relatively easy to understand categories: non-formal and formal.

1. Non-formal fallacies

Non-formal fallacies are those in which the error of the reasoning has to do with the content of the premises.. In this type of fallacies, what is expressed in the premises does not allow the conclusion to be reached, regardless of whether the premises are true or not.

In other words, irrational ideas about how the world works are appealed to in order to give the impression that what is said is true.

1.1. Ad ignorantiam fallacy

In the fallacy ad ignorantiam, an attempt is made to take for granted the veracity of an idea simply because it cannot be demonstrated to be false..

The famous meme of the Flying Spaghetti Monster is based on this type of fallacy: since it cannot be proved that there is no invisible entity made of spaghetti and meatballs that is also the creator of the world and its inhabitants, it must be real.

1.2. Fallacy ad verecundiam

The fallacy ad verecundiam, or fallacy of authority, links the veracity of a proposition to the authority of the one who defends it, as if it provided an absolute guarantee..

For example, it is common to argue that Sigmund Freud's theories on mental processes are valid because their author was a neurologist.

Argument ad consequentiam

This type of fallacy attempts to show that the validity or not of an idea depends on whether that which can be inferred from it is desirable or undesirable..

For example, an argument ad consequentiam would be to assume that the chances of the army staging a coup d'état in a country are very low because the opposite scenario would be a severe blow to the citizenry.

1.4. Hasty generalization

This fallacy is a generalization that is not based on sufficient data..

The classic example is found in stereotypes about the inhabitants of certain countries, which can lead to fallaciously thinking, for example, that if someone is Scottish he must be characterized by his stinginess.

1.5. Anecdotal fallacy

As its name indicates, in the anecdotal fallacy the problem is that we start from anecdotal observations to reach conclusions. The problem here is not so much the lack of information, as in the case of hasty generalization, but rather the poor quality of the information from which we start.

For example, when we try to estimate the efficacy of a type of psychotherapy based on our personal experience, we are falling into this type of fallacy, since we have not even adopted a scientific methodology to systematically extract information about the efficacy of that procedure, nor have we taken into account our biases.

1.6. Straw man fallacy

This fallacy does not criticize the opponent's ideas, but a caricatured and manipulated image of them..

An example would be found in a line of argument in which a political party is criticized for being nationalist, characterizing it as something very close to Hitler's party.

1.7. Post hoc ergo propter hoc

This is a type of fallacy in which it is taken for granted that if one phenomenon occurs after another, it is caused by the latter, in the absence of further evidence to indicate that this is the case..

For example, one could try to argue that the sudden rise in the price of an organization's shares has occurred because the start of the big game hunting season has already arrived in Badajoz.

1.8. Ad hominem fallacy

This fallacy denies the veracity of certain ideas or conclusions by highlighting their negative characteristics (more or less distorted and distorted). (more or less distorted and exaggerated) of the person who defends them, instead of criticizing the idea itself or the reasoning that has led to it.

An example of this fallacy would be found in a case in which someone disparages the ideas of a thinker arguing that he does not take care of his personal image.

However, it is necessary to know how to distinguish this type of fallacy, one must know how to distinguish this type of fallacy from legitimate arguments referring to the characteristics of a specific person. For example, appealing to the lack of university studies of a person talking about advanced concepts of quantum physics can be considered a valid argument, since the information given is related to the subject matter of the dialogue.

1.9. Midpoint fallacy

In the midpoint fallacy, a supposedly equidistant position is adopted without taking into account whether all the information considered is equally valid and consistent. and consistent.

For example, if we are informed that a person has invented a new type of pseudotherapy and we are asked whether this practice should be included in the public health system, we would be falling into the fallacy of the middle ground if we assume that the health services should give it the same importance as the forms of therapy already offered and that have demonstrated their effectiveness.

1.10. Tu quoque fallacy

In this type of informal fallacy, creates the illusion of refuting an argument by pointing out that the person who proposes it does not act in a manner consistent with that idea..

It can be understood as a variant of the ad hominem fallacy, since it attempts to disguise criticism of the person as criticism of his reasoning.

1.11. Fallacy of composition

This error in reasoning occurs when we try to arrive at conclusions about a to arrive at conclusions about an element based on appreciations about one of its parts.. For example:

• Sodium explodes on contact with water.
• Salt contains sodium.
• Salt explodes in contact with water.

Formal fallacies

Formal fallacies are formal fallacies not because the content of the premise does not allow the conclusion to be reached, but rather because the relation between the premises makes the inference invalid.

Therefore, their faults do not depend on the content, but on the way in which the premises are linked, and they are not false because we have introduced irrelevant and unnecessary ideas in our reasoning, but because there is no coherence in the arguments we use.

The formal fallacy can be detected by replacing all the elements of the premises by symbols and seeing if the reasoning conforms to the logical rules.

2.1. Negation of the antecedent

This type of fallacy starts from a conditional of the type "if I give him a gift, he will be my friend", and when the first conditional is denied, the second conditional is denied.and when the first element is denied, it is incorrectly inferred that the second element is also denied: "if I do not give him a gift, he will not be my friend".

2.2. Affirmation of the consequent

This type of fallacy also starts from a conditional, but in this case the second element is affirmed and it is incorrectly inferred that the antecedent is true: "if I do not give him a gift, he will not be my friend". that the antecedent is true:

"If I pass, I uncork the champagne".

"I uncork the champagne, so I approve".

2.3. Undistributed middle term

In this fallacy, the middle term of a syllogism, which is the one that connects two propositions and does not appear in the conclusion, does not cover in the premises all the elements of the set.

Example:

"Every Frenchman is European".

"Some Russian is European".

"Therefore, some Russian is French".