Logic[1] is an interdisciplinary field which studies truth and reasoning. Informal logic seeks to characterize valid arguments informally, for instance by listing varieties of fallacies. Formal logic represents statements and argument patterns symbolically, using formal systems such as first order logic. Within formal logic, mathematical logic studies the mathematical characteristics of logical systems, while philosophical logic applies them to philosophical problems such as the nature of meaning, knowledge, and existence. Systems of formal logic are also applied in other fields including linguistics, cognitive science, and computer science.

Logic has been studied since Antiquity, early approaches including Aristotelian logic, stoic logic, Anviksiki, and the mohists. Modern formal logic has its roots in the work of late 19th century mathematicians such as Gottlob Frege.