level: Basic (2) [ order by level] an error in logical thinking as defined by the study of logic or philosophical practice. It consists in drawing a conclusion from certain premises in a way that is unwarranted by the laws of logic.
In philosophy, a logical fallacy or a formal fallacy is a pattern of reasoning which is always or at least most commonly wrong. This is due to a flaw in the structure of the argument which renders the argument invalid. A formal fallacy is contrasted with an informal fallacy, which has a valid logical form, but is false due to one or more of its premises being false.