Fallacies: Definition, Types and Examples

The fallacies they are a kind of deceptive reasoning even if it seems true, based on arguments with little solidity, that try to convince another person intentionally or involuntarily. These erroneous beliefs derive from a logically incorrect reasoning that detracts from the argument.

Because there is no agreement on how to define and classify fallacies, there are several definitions about the term. The most 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 exprofeso 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 types of known fallacies can be listed by hundreds, because their number can be infinite. Generally fallacies include definitions, explanations or other elements of reasoning.

The term fallacy is commonly used as a synonym for falsehood or false belief. However, most fallacies involve mistakes that are made during an informal and everyday discussion. Fallacies are not of interest only for logic, but also for 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 Latin fallacy which means"deception." It is defined as an invalid argument from the deductive or inductively weak point of view.

This fallacious argument may also contain an unjustified premise or completely ignore the relevant available evidence, which should be known by the arguer.

Fallacies can be intentionally committed in order to persuade or manipulate another person, but there are other types of fallacies that are involuntary 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, we must pay close attention to unmask them.

Good arguments

Good arguments are those that are 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 discard unconventional scientific knowledge and to label it as false. It happens for example when a new discovery arises.

This leads to a fallacious scientific reasoning, because it is based on the premise of false imposed previously, although some researcher could argue that all the premises must be true in order to end the discussion.

Other theories

Another theory holds that the fallacy is based on the lack of adequate evidence to support a belief, and that lack is disguised to make the evidence seem adequate.

Some authors recommend that the fallacy be expressly characterized as a violation of the rules of good reasoning, critical discussion, adequate communication and the resolution of disputes. The problem with this approach is the disagreement that exists about 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 verbally and nonverbally or relative to things.

There are many ways to classify them, but in general the classification that is most used is the categorization of formal and informal.

Formal fallacies

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

The pattern that follows this type of fallacies is:

Cats have four legs.

Silvestre is a cat.

Therefore: Silvestre has four legs.

The formal fallacies can be detected by replacing the elements that make up the premises with symbols, and then see 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.

Example

There are dark clouds in the sky.

Dark clouds mean it's going to rain.

Then today it will rain.

- Denial of the antecedent

This fallacy is determined by a conditional element.

Example

If I give to my friends, they will love me more.

This leads to an erroneous inference in denying it:"If I do not offer my friends, they will not 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.

Example

Her new boyfriend has an old car.

It means that he is poor.

She should not be with him.

- Fallacy of the masked man

It is also called intentional fallacy and involves replacing one of the parties. Thus, when the two things exchanged are identical, it is assumed that the argument is valid.

Example

The police reported that the thief who robbed Jesus' house had a beard.

The neighbor of Jesus wears a beard.

Therefore, the thief is the neighbor of Jesus.

- Average term not distributed

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

Example

Every Mexican is Latin American.

A Panamanian is Latin American.

Therefore, some Panamanian is Mexican.

Informal fallacies

Informal (inductive) fallacies depend on the content itself and perhaps on the purpose of reasoning. They are found 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 there is a presumption of truth but there is no evidence of it, false reasoning can be provoked. Two of these fallacies are:

- Complex question fallacy, which implies reaching questionable assumptions.

Example

"Are you going to admit that it does not work?"If the answer is yes, the presumption is shown, but if it is answered no, it means that the statement is true but you do not want to admit it.

- Hasty generalization fallacy, based on a unique abnormal situation. It is the opposite of the fallacy of generalization.

Example

"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 appealing to emotions and not to logic. Here are included:

- Appeal to authority, known as Argumentum ad Verecundiam ; that is, argument of modesty. The veracity of the argument is linked to the authority or prestige of the person who defends it. It is a logical fallacy because it does not depend on the person making the claim.

Example

"Astronauts believe in God. Then God exists, or do you think you know more than them?"

- 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 endorses it.

Example

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

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

Example

"What can this deputy know about the suffering of the people, if it is a child of father and mother?"

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

Example

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

- Fallacies of ambiguity

The lack of clarity and a simple misunderstanding can cause various types of these fallacies:

- Acute fallacies, those that occur when the way in which a word is emphasized is not clear or generates confusion.

Example

"A"says:"We will defend the rights of men to their ultimate consequences."

"B"responds:"It is clear that they will not defend those of women then".

Or the classic example of the sentence"I did not take the exam yesterday", which lends itself to different interpretations.

- Fallacy fallacies, which happen when the words used have different meanings.

Example

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.

Example

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

Politician 2:"You propose leaving the country unprotected against external enemies!".

Articles of interest

Fallacy ad baculum .

Fallacies of ambiguity .

Ad Misericordiam .

References

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