log·​ic ˈlä-jik How to pronounce logic (audio)
: a science that deals with the principles and criteria of validity of inference and demonstration : the science of the formal principles of reasoning
a professor of logic
: a branch or variety of logic
modal logic
Boolean logic
: a branch of semiotics
especially : syntactics
: the formal principles of a branch of knowledge
the logic of grammar
: a particular mode of reasoning viewed as valid or faulty
She spent a long time explaining the situation, but he failed to see her logic.
: relevance, propriety
could not understand the logic of such an action
: interrelation or sequence of facts or events when seen as inevitable or predictable
By the logic of events, anarchy leads to dictatorship.
: 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
logician noun

Did you know?

How are logistics and logic related?

Logistics follows the same pattern of other plural nouns—such as ballistics, linguistics, statistics, or physics—that represent fields of study and take either a singular or plural verb.

Logic, used strictly in the singular, is a science that deals with the formal principles of reason. If a visitor walks in the house with a wet umbrella, it is logical for one to assume that it is raining outside. Logistics, which involves such concerns as the delivery of personnel or supplies in an efficient manner, can often employ logic, such as by reasoning out the path least likely to interrupt the flow of a delivery:

As with many other areas of the economy, the digital revolution is having a profound effect on delivery logistics. The combination of mobile computing, analytics, and cloud services, all of which are fueled by the Internet of Things (IoT), is changing how delivery and fulfillment companies are conducting their operations.
—Andrew Meola, Business Insider, 14 Oct. 2016

Both logic and logistics ultimately derive from the Greek logos, meaning "reason." But while logic derives directly from Greek, logistics took a longer route, first passing into French as logistique, meaning "art of calculating," and then into English from there.

Example Sentences

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 See More
Recent Examples on the Web Those systems are summoned in turn by a master control program built in the games engine Unity, according to logic set by the band. WIRED, 24 Nov. 2022 Malis' logic is weather is less likely to disrupt flying first thing, even if there were delays the day before, the system has usually reset overnight. CNN, 23 Nov. 2022 There is historical logic here: The building was constructed in 1970 as a recording studio, with spaces for multiple musicians to work concurrently without polluting one another’s sessions. Caity Weaver, New York Times, 23 Nov. 2022 The classic puzzle game of inductive logic is back, purer, and clearer than ever! Carlyn Kranking, Smithsonian Magazine, 23 Nov. 2022 Twitter users immediately pushed back on Musk's logic. Irina Ivanova, CBS News, 21 Nov. 2022 By Guy’s logic, the Patriots’ bye last week couldn’t have come at a better time. Julian Benbow, BostonGlobe.com, 19 Nov. 2022 There’s no logic to any showbiz career, but some paths are more surprising than others. Tim Gray, Variety, 18 Nov. 2022 All these excesses are held together not with airtight plotting, but through a hazy dream logic that at times feels downright opaque. Angie Han, The Hollywood Reporter, 17 Nov. 2022 See More

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'logic.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Word History


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, in the meaning defined at sense 1a(1)

Time Traveler
The first known use of logic was in the 12th century

Dictionary Entries Near logic

Cite this Entry

“Logic.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/logic. Accessed 4 Dec. 2022.

Kids Definition



log·​ic ˈläj-ik How to pronounce logic (audio)
: the study of the rules and tests of sound reasoning
: reasoning sense 1
especially : sound reasoning
no logic in that remark
: connection (as of facts or events) in a way that seems reasonable
the logic of a situation
: the arrangement of circuit elements (as in a computer) needed for computation

More from Merriam-Webster on logic

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