Fallacies: Definition, Types And Examples

The fallacies are a kind of specious reasoning though real enough, based on arguments with little strength, trying to convince another person intentionally or unintentionally. These erroneous beliefs derive from logically incorrect reasoning that makes the argument invalid.

Because there is no agreement on how to define and classify fallacies, there are various definitions of the term. The most widely accepted defines fallacies as deductively invalid or very weak arguments, from the inductive point of view.


The lie or deception underlies the argument, since it contains an unjustified false premise. Some fallacies are constructed expressly or deliberately with the intention of persuading others; other times, they are deceptions that are committed involuntarily, either through ignorance or simple carelessness.

The first to classify the fallacies was Aristotle. Since then, only the known types of fallacies can be listed by the hundreds, because their number can be infinite. Fallacies generally include definitions, explanations, or other elements of reasoning.

The term fallacy is commonly used as a synonym for a lie or false belief. However, most fallacies involve mistakes that are made during an informal, everyday discussion. Fallacies are not of interest only to logic, but also to other disciplines and fields of knowledge.

They are present in daily life and are manifested in common language and in other areas such as political discourse, journalism, advertising, law and in any other field of knowledge that requires argumentation and persuasion.

Definition of fallacy

The word fallacy comes from the Latin fallacia which means “deception.” It is defined as an invalid argument deductively or inductively very weak.

This fallacious argumentation may also contain an unwarranted premise or completely ignore the relevant available evidence, which should be known to the person arguing.

Fallacies can be committed intentionally in order to persuade or manipulate another person, but there are other types of fallacies that are unintentional or unintentional and are committed out of ignorance or carelessness.

Sometimes it is difficult to detect them because they are very persuasive and subtle; therefore you have to pay close attention to unmask them.

Good arguments

The good arguments are those deductively valid or also inductively strong. These only contain true and solid premises, which are not just requests.

The problem with this definition is that it leads to discarding unconventional scientific knowledge and labeling it as false. It happens for example when a new discovery arises. 

This leads to fallacious scientific reasoning, because it starts from the false premise imposed above, although some researcher might argue that all the premises must be true in order to end the discussion.

Other theories

Another theory holds that the fallacy stems from the lack of adequate proof to support a belief, and that lack is disguised to make the proof appear adequate.

Some authors recommend that the fallacy be expressly characterized as a violation of the rules of good reasoning, critical discussion, adequate communication, and dispute resolution. The problem with this approach is the disagreement that exists on how to characterize such norms.

In the opinion of some researchers, all these previous definitions are very broad and do not distinguish between real fallacies, the most serious errors and mere mistakes.

Therefore, it is believed that a general theory of fallacies should be sought to help distinguish between fallacious reasoning and non-fallacious reasoning.

Types of fallacies and examples

Since Aristotle, fallacies have been classified in different ways. The Greek philosopher classified them as verbal and non-verbal or relating to things.

There are many ways to classify them, but generally the most commonly used classification is the formal and informal categorization.

Formal fallacies

The formal (deductive) fallacy is detected by critical examination of logical reasoning. In other words, there is no concatenation between the conclusion and the premise, although the reasoning pattern seems logical, it is always incorrect.

The pattern that this type of fallacy follows is:

Cats have four legs.

Silvestre is a cat.

Therefore: Silvestre has four legs.

Formal fallacies can be detected by replacing the elements that make up the premises by symbols, and then seeing if the reasoning is adjusted to the rules of logic. Some subtypes of formal fallacies are:

– Appeal to probability

With probability and prior knowledge, what seems logical is taken for granted, because it is quite probable.


There are dark clouds in the sky.

Dark clouds mean it’s going to rain.

Then today it will rain.

– Denial of antecedent

This fallacy is determined by a conditional element.


If I toast my friends, they will love me more.

This leads to an erroneous inference by denying it: “If I don’t toast my friends, they won’t love me.”

– Fallacy of bad reasons

It is also known as Argumentum ad Logicam . Here it is assumed that the conclusion is bad, since the arguments are also bad.


Her new boyfriend has an old car.

It means that it is poor.

She shouldn’t be with him.

– Fallacy of the Masked Man

It is also called an intentional fallacy and involves substituting one of the parts. Thus, when the two things exchanged are identical, the argument is assumed to be valid.


Police reported that the thief who robbed Jesus’ home had a beard.

Jesus’ neighbor wears a beard.

Therefore, the thief is the neighbor of Jesus.

– Undistributed middle term

The middle term of the syllogism does not cover in its premises all the members of the set or category


Every Mexican is Latin American.

A Panamanian is Latin American.

Therefore, some Panamanians are Mexican.

Informal fallacies

Informal (inductive) fallacies depend on the actual content and perhaps the purpose of the reasoning. They are encountered more often than formal fallacies and their various types are almost infinite.

Some authors classify them into subcategories, precisely because of their extensive variety:

– Fallacies of presumption

When the presumption of truth exists but there is no evidence of it, fallacious reasoning can be provoked. Two of these these fallacies are:

– Complex question fallacy, which implies arriving at questionable assumptions.


Are you going to admit that that doesn’t work? If the answer is affirmative, the presumption is demonstrated, but if the answer is no, it means that the statement is true but it is not intended to be admitted.

– Fallacy of hasty generalization, based on a single abnormal situation. It is the opposite of the fallacy of generalization.


Hitler was a vegetarian. So vegetarians are not to be trusted ”.

– Relevance fallacies

This type of fallacy seeks to persuade a person with irrelevant information, through the appeal to emotions and not to logic. These include:

– Appeal to the authority, known as  Argumentum ad Verecundia ; that is to say, argument from modesty. The veracity of the argument is linked to the authority or prestige of the person defending it. It is a logical fallacy because it does not depend on the person making the claim.


Astronauts believe in God. So God exists, or do you think you know more than they do? ».

– Appeal to popular opinion, in which the opinion of the majority is followed and a belief or idea is taken for granted only because public opinion supports it.


“Everyone buys that brand of shoes, it must be very comfortable.”

– Attack the person, also called Ad Hominem . Its use is very frequent in political debate, since objective arguments are replaced by personal disqualification.


“What can that deputy know about the suffering of the people, if he is a son of mom and dad.”

– Bandwagon fallacy, referring to those that contain arguments that are attractive due to their popularity and social trends.


«Green food prevents many diseases. I will eat only unprocessed foods so as not to get sick.

– Fallacies of ambiguity

Lack of clarity and a simple misunderstanding can lead to various types of these fallacies:

– Accent fallacies, those that occur when the way in which a word is emphasized is unclear or creates confusion.


“A” says: “We will defend the rights of men to their last consequences.”

“B” responds: “It is clear that they will not defend the women then.”

Or the classic example of the sentence “I did not take the test yesterday”, which is open to various interpretations.

– Fallacies of mistake, which happen when the words that are used have different meanings.


Have faith in science and have faith in God.

– Straw man fallacies, which refer to misrepresentations that are introduced to make an argument seem weak.


Politician 1: “The debt is very high, we should not spend more on Defense.”

Politician 2: “You propose to leave the country unprotected against external enemies!”

Articles of interest

Ad baculum fallacy.

Fallacies of ambiguity.

Ad Mercy.


  1. Bradley Dowden. Fallacies. Retrieved March 7, 2018 from iep.utm.edu
  2. What is a fallacy. Consulted from philosophy.hku.hk
  3. Types of Logical Fallacies. Consulted of examples.yourdictionary.com
  4. Fallacies. Consulted from writingcenter.unc.edu
  5. Fallacies. Consulted from plato.stanford.edu
  6. The Argumentative Fallacies. Consulted from mesacc.edu

Add a Comment

Your email address will not be published. Required fields are marked *