noun \ˈlä-jik\

: a proper or reasonable way of thinking about or understanding something

: a particular way of thinking about something

: the science that studies the formal processes used in thinking and reasoning

Full Definition of LOGIC

a (1) :  a science that deals with the principles and criteria of validity of inference and demonstration :  the science of the formal principles of reasoning (2) :  a branch or variety of logic <modal logic> <Boolean logic> (3) :  a branch of semiotics; especially :  syntactics (4) :  the formal principles of a branch of knowledge
b (1) :  a particular mode of reasoning viewed as valid or faulty
(2) :  relevance, propriety
c :  interrelation or sequence of facts or events when seen as inevitable or predictable
d :  the arrangement of circuit elements (as in a computer) needed for computation; also :  the circuits themselves
:  something that forces a decision apart from or in opposition to reason <the logic of war>
lo·gi·cian \lō-ˈji-shən\ noun

Examples of LOGIC

  1. If you just use a little logic, you'll see I'm right.
  2. There's no logic in your reasoning.
  3. There's some logic to what he says.
  4. There's a certain logic in what he says.
  5. The revolution proceeded according to its own logic.
  6. the logic of the situation

Origin of LOGIC

Middle English logik, from Anglo-French, from Latin logica, from Greek logikē, from feminine of logikos of reason, from logos reason — more at legend
First Known Use: 12th century

Other Logic Terms

a posteriori, connotation, corollary, inference, mutually exclusive, paradox, postulate, syllogism


noun    (Concise Encyclopedia)

Study of inference and argument. Inferences are rule-governed steps from one or more propositions, known as premises, to another proposition, called the conclusion. A deductive inference is one that is intended to be valid, where a valid inference is one in which the conclusion must be true if the premises are true (see deduction; validity). All other inferences are called inductive (see induction). In a narrow sense, logic is the study of deductive inferences. In a still narrower sense, it is the study of inferences that depend on concepts that are expressed by the “logical constants,” including: (1) propositional connectives such as “not,” (symbolized as ¬), “and” (symbolized as ), “or” (symbolized as ), and “if-then” (symbolized as ), (2) the existential and universal quantifiers, “(x)” and “(x),” often rendered in English as “There is an x such that …” and “For any (all) x, …,” respectively, (3) the concept of identity (expressed by “=”), and (4) some notion of predication. The study of the logical constants in (1) alone is known as the propositional calculus; the study of (1) through (4) is called first-order predicate calculus with identity. The logical form of a proposition is the entity obtained by replacing all nonlogical concepts in the proposition by variables. The study of the relations between such uninterpreted formulas is called formal logic. See also deontic logic; modal logic.


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