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.

Examples of logic in a Sentence

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 More local investment - so the logic goes - will encourage U.K. companies to stay centered on home turf. Trevor Clawson, Forbes, 16 Feb. 2024 Hers is a world where logic does not reign, independence is essential and the unconscious is a mechanism for self-knowledge. Christopher Knight, Los Angeles Times, 16 Feb. 2024 The court applied the same logic to a similar case involving YouTube, avoiding a potentially explosive fight over online liability laws in general. Adi Robertson, The Verge, 14 Feb. 2024 But logic says Kansas City can’t keep beating teams that were clearly superior in the regular season. Baltimore Sun Staff, Baltimore Sun, 9 Feb. 2024 At the same time, this very question possesses a geometric sort of logic that circumscribes the entirety of the Trump era. Robert Draper, New York Times, 8 Feb. 2024 McDuffie applied the same logic to the provision expanding pretrial detention for people charged with violent crimes, something the council passed last summer on a temporary basis. Michael Brice-Saddler, Washington Post, 7 Feb. 2024 But many security problems are in the logic underlying the code. IEEE Spectrum, 6 Feb. 2024 What this logic elides is that the process of adding water during bottling is both precise and exceptionally important. Jason O'Bryan, Robb Report, 4 Feb. 2024 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'logic.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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 20 Feb. 2024.

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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