falacia

Falacia, in logic and rhetoric, refers to a flaw in reasoning that weakens an argument or makes it misleading. The term is used in many languages, including Spanish, where falacia means fallacy. Fallacies can be formal, arising from an invalid inference in the logical form, or informal, arising from content, language, or questionable assumptions.

Formal fallacies involve failures in the structure of the argument, such as affirming the consequent or denying the antecedent. Informal fallacies arise from irrelevant premises, questionable assumptions, or linguistic tricks. Common informal fallacies include ad hominem, straw man, false cause, non sequiturs, appeal to authority, appeal to emotion, begging the question, hasty generalization, slippery slope, false dilemma, and circular reasoning.

Identification and assessment rely on careful evaluation of premises, evidence, and whether the conclusion logically follows. Some fallacies reflect cognitive biases or rhetorical strategies that people use intentionally to persuade; others are inadvertent mistakes in reasoning. Distinguishing fallacies from legitimate arguments requires clarity about definitions, evidence, and the connections between premises and conclusions.

In practice, recognizing falacias helps in evaluating arguments in debate, science, law, and everyday reasoning. While not every weak argument is a formal fallacy, awareness of common patterns supports clearer, more robust thinking and reduces susceptibility to manipulation.