illogical

Illogical is an adjective describing reasoning, conclusions, or claims that do not follow from premises in a coherent or valid way. The term is commonly used to indicate that an argument or line of thought violates the laws of logic, or fails to meet standards of sound reasoning, such as validity, consistency, or sufficiency of evidence. In everyday language, people label something as illogical when it seems contradictory, implausible, or unsupported by relevant facts.

Origin and usage: illogical is formed from ill (bad) plus logical, with roots in the broader history of logic and language. It is distinct from irrational, which emphasizes beliefs or actions not guided by reason or dominated by emotion, and from nonsensical, which refers to a lack of sense or meaning.

Examples of illogical reasoning include non sequiturs, where the conclusion does not logically follow from the premises; fallacies that rely on irrelevant or insufficient evidence; or conclusions drawn from faulty assumptions. Illogicality can manifest in formal arguments, informal discourse, or rhetorical devices, and it is a common focus in critical thinking, argument analysis, and education.

In philosophy and logic, illogical reasoning is analyzed to identify gaps, inconsistencies, or unjustified inferences. Recognizing illogical elements helps evaluate the strength of arguments, improve clarity, and distinguish legitimate conclusions from flawed ones.