What does logic mean?
Logic is the study and practice of sound reasoning: how conclusions can be drawn from premises, whether through deduction, induction, or other forms of argument. In everyday use, the word refers more broadly to a coherent way of thinking or the reasons behind a decision. Saying that a course of action has “logic” suggests that it follows a rational pattern rather than being arbitrary or based on ignorance. Logic is not simply a synonym for truth, because an argument can be presented logically yet rest on false assumptions, and a person may make a sound judgment without expressing it in formal terms. The word also names formal systems of reasoning, such as classical logic, and has important applications in mathematics, law, computer science, philosophy, and everyday problem-solving. Its familiar cousin “logical” describes conclusions reached through reasoning, while “logically” describes how an argument proceeds. Despite its association with strictness and abstraction, logic is valuable because it makes the structure of thought explicit, allowing people to examine why a conclusion is persuasive, questionable, or mistaken.
The principles of valid reasoning, a formal system of argument, or a coherent method underlying a decision or interpretation.
"The policy seems sound in principle, though its implementation lacks logic."
The noun is usually uncountable. In specialist writing, “a logic” can refer to a particular formal system, while the plural “logics” denotes distinct systems of reasoning.
To work out or calculate something by applying logical reasoning.
"The analyst continued to logic the figures, looking for an error."
This verb is chiefly informal and uncommon in formal English.
The ordinary noun is normally uncountable. The plural “logics” is uncommon and chiefly refers to distinct systems or bodies of formal reasoning.
"Modern logics provide formal ways to analyze many forms of argument."
Logic descends from the Greek logos, meaning “word” or “reason,” a reminder that the discipline began with the disciplined use of language.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does logic come from?
English borrowed the word in the Middle English period through Old French logique, from Latin logica, a term associated with Greek logicē, “the art of reasoning.” Greek logicē was derived from logos, meaning “word,” “discourse,” or “reason.” The same Greek root also underlies cognates and related formations such as logarithm, dialogue, monologue, and logotype.
Related word forms
How logic is actually used
Logic is normally an uncountable noun, although the uncommon plural “logics” is used for distinct systems of formal reasoning. The verb is chiefly informal and is much less common than the noun. In everyday use, “logic” can describe the rational basis for a decision, including an implicit or unstated rationale.
Easily confused with logic
Logic concerns reasoning and valid argument, whereas logistics concerns the organization and movement of people, materials, or information.