# logic

## log·ic

*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*

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

## Origin of *LOGIC*

*logik,*from Anglo-French, from Latin

*logica,*from Greek

*logikē,*from feminine of

*logikos*of reason, from

*logos*reason — more at legend

## Related to *LOGIC*

- Synonyms
- intellection, ratiocination, reason, reasoning, sense

## Other Logic Terms

## logic

*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.

## Learn More About *LOGIC*

## Browse

## Seen & Heard

What made you want to look up *logic*? Please tell us where you read or heard it (including the quote, if possible).