logic

noun

log·​ic ˈlä-jik 

1

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

a professor of logic

(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

the logic of grammar

b(1)

: 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.

(2)

: relevance, propriety

could not understand the logic of such an action

c

: interrelation or sequence of facts or events when seen as inevitable or predictable

By the logic of events, anarchy leads to dictatorship.

d

: the arrangement of circuit elements (as in a computer) needed for computation

also : the circuits themselves

2

: something that forces a decision apart from or in opposition to reason

the logic of war

logician

lō-ˈji-shən 

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.

Synonyms

• reasoning

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

Recent Examples on the Web

Modern conservatism developed its own history and internal logic, emerging not merely in opposition but alongside liberalism as a powerful response to the social and economic upheavals of the early 20th century. —Allan J. Lichtman, MSNBC Newsweek, 18 Sep. 2025

If threatened, the brain can be overtaken by the emotional response in a moment, abandoning logic or reason. —Wilson Luna, Forbes.com, 17 Sep. 2025

With both of these energies at odds with each other, there is friction between the head and heart, the need for clarity and logic versus surrender and trust. —Valerie Mesa, PEOPLE, 17 Sep. 2025

The logic puzzles seemed tailor-made for someone like Morgan, a high-IQ intellectual who consults with the police and notices things others miss. —Kelly Lawler, USA Today, 17 Sep. 2025

Word History

Etymology

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)

Phrases Containing logic

• against all logic
• chop logic
• defy logic
• fuzzy logic
• logic bomb
• mathematical logic
• symbolic logic

Rhymes for logic

• tajik
• yogic
• bacteriologic
• histopathologic
• paleontologic
• biologic
• chronologic
• cytologic
• demagogic
• dialogic
• ecologic
• geologic

Kids Definition

logic

noun

log·​ic ˈläj-ik 

1

: the study of the rules and tests of sound reasoning

2

: reasoning sense 1

especially : sound reasoning

no logic in that remark

3

: connection (as of facts or events) in a way that seems reasonable

the logic of a situation

4

: the arrangement of circuit elements (as in a computer) needed for computation