4 meanings: 1. an incorrect or misleading notion or opinion based on inaccurate facts or invalid reasoning 2. unsound or.... Click for more definitions. A fallacy is a flaw in reasoning that makes an argument invalid or unsound. Learn about the history, classification and examples of fallacies in logic, rhetoric and argumentation theory. Fallacy definition: a deceptive, misleading, or false notion, belief, etc... See examples of FALLACY used in a sentence. Fallacy, in logic, erroneous reasoning that has the appearance of soundness. In logic an argument consists of a set of statements, the premises, whose truth supposedly supports the truth of a single statement called the conclusion of the argument. An argument is deductively valid when the truth of
