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Definition of Falacia

The word falacia, fallacy in English, refers to a deception, lie or false comment made by a person with good or bad intentions.

Sometimes, when it is a bad intention, a fallacy is said in order not to hurt the person who wants to hide the truth or simply to deceive him/her. When it is a good intention, usually, the one who utters it does it subtly and unknowingly.

In short, it is a comment that seems true, but is not.


  1. Lie
  2. Deception
  3. False testimony
  4. Fiction
  5. Falsehood
  6. Defamation
  7. Fraud
  8. Deception


The word fallacy comes from the Latin fallacia, in association with the verb fallere which in its original meaning refers to lying, deceit or deception.

It also derives from the adjective fallacious which comes from the Latin fallax or fallacis which denotes the false comment or the person who confers it as true, we could say that this is the most marked difference between fallacy and lie. The fallacy is an adjective that tries to disguise the truth and is so subtle that it is almost imperceptible to detect it.

In the field of philosophy and other sciences that study theories and other arguments that must be true, the term fallacy is used, above all, to denote those theories that do not have sufficient scientific basis.


There are different types of fallacy, the ad hominem fallacy corresponds to a discrediting of an argument while the ad populum fallacy means a demagogic argument in which one tries to convince people of an idea by using their emotions.