Logic (from Greek: λογική, logikḗ, 'possessed of reason, intellectual, dialectical, argumentative') is the systematic study of valid rules of inference, i.e. the relations that lead to the acceptance of one proposition (the conclusion) on the basis of a set of other propositions (premises). More broadly, logic is the analysis and appraisal of arguments. There is no universal agreement as to the exact definition and boundaries of logic, hence the issue still remains one of the main subjects of research and debates in the field of philosophy of logic (see ). However, it has traditionally included the classification of arguments; the systematic exposition of the logical forms; the validity and soundness of deductive reasoning; the strength of inductive reasoning; the study of formal proofs and inference (including paradoxes and fallacies); and the study of syntax and semantics. A good argument not only possesses validity and soundness (or strength, in induction), but it also avoids circular dependencies, is clearly stated, relevant, and consistent; otherwise it is useless for reasoning and persuasion, and is classified as a fallacy. In ordinary discourse, inferences may be signified by words such as therefore, thus, hence, ergo, and so on. Historically, logic has been studied in philosophy (since ancient times) and mathematics (since the mid-19th century). More recently, logic has been studied in cognitive science, which draws on computer science, linguistics, philosophy and psychology, among other disciplines. A logician is any person, often a philosopher or mathematician, whose topic of scholarly study is logic.
La lógica es la ciencia formal y rama tanto de la filosofía como de las matemáticas que estudia los principios de la demostración y la inferencia válida, las falacias, las paradojas y la noción de verdad. La lógica matemática es la rama más matemática de la lógica, que estudia la inferencia mediante sistemas formales como la lógica proposicional, la lógica de primer orden y la lógica modal. La lógica computacional es la aplicación de la lógica matemática a las ciencias de la computación. La lógica filosófica utiliza los métodos y resultados de la lógica moderna para el estudio de problemas filosóficos. Los orígenes de la lógica se remontan a la Edad Antigua, con brotes independientes en China, India y Grecia. Desde entonces, la lógica tradicionalmente se considera una rama de la filosofía, pero en el siglo XX la lógica ha pasado a ser principalmente la lógica matemática, y por lo tanto ahora también se considera parte de las matemáticas, e incluso una ciencia formal independiente.