logic

logic — noun

1. the set of reasons or the way of thinking that makes a particular action, decisi

1.nounB1
Definition

the set of reasons or the way of thinking that makes a particular action, decision, or explanation seem sensible and understandable

Example

Elena could not understand the logic of her friend's decision to quit a well-paid job.

logic of [someone's] decision

There is no logic in spending your whole salary on things you never use.

logic in [doing something] — pattern for evaluating actions

Common collocations
  • logic of
  • logic in
  • logic behind
  • follow the logic
  • understand the logic
  • by the same logic
Synonyms
  • reasoning

    the same sense of using reason, but 'reasoning' focuses on the mental process, while 'logic' focuses on the structure of the argument

  • rationale

    more formal; refers to the underlying reasons for a decision or policy, often in business or academic contexts

  • sense

    more informal; 'it makes sense' is a common equivalent for 'there is logic in it'

  • justification

    focuses on the act of showing something to be right or reasonable, often after the fact

Antonyms

Grammar Patterns

logic + of/in/behind + noun phrase

Usage Note

Often used with prepositions 'of', 'in', or 'behind' to explain why someone thinks or acts in a certain way. Common in both everyday conversation and formal writing.

Common Mistakes

This plan has no logic reason.
This plan has no logic.' or 'This plan has no logical reason.
'logic' is a noun, not an adjective; use 'logical' as the adjective form.
I can't find the logic from his argument.
I can't find the logic in his argument.
use 'in' not 'from' when referring to the content of an argument.

2. the study of the rules and methods that people use to reach correct conclusions

2.nounB2
Definition

the study of the rules and methods that people use to reach correct conclusions from given facts or statements

Example

Aristotle is often called the father of formal logic for his early work on how people reason.

formal logic — academic discipline

In her logic class, Ayana learned how to test whether the premises of an argument truly support its conclusion.

logic class — learning formal reasoning skills in an academic setting

Common collocations
  • formal logic
  • symbolic logic
  • study logic
  • course in logic
  • principles of logic
Synonyms
  • reasoning

    broader term; logic is the formal study of reasoning

  • dialectic

    a more specific method of reasoning through argument and counter-argument; mostly used in philosophy

Grammar Patterns

logic as a field of study

Usage Note

In this sense, 'logic' is an academic subject with sub-fields such as formal logic, symbolic logic, and predicate logic. It is a count noun only in specialised contexts ('the logics of different philosophical systems').

Common Mistakes

I studied a logic in university.
I studied logic at university.
do not use the article 'a' with logic as an uncountable academic subject.
The logic is the science of reasoning.
Logic is the science of reasoning.
no definite article needed when referring to the subject in general.

3. the set of rules and electronic arrangements inside a computer or machine that c

3.nounB2
Definition

the set of rules and electronic arrangements inside a computer or machine that control how it processes information and performs tasks

Example

A logic gate is a simple electronic circuit that makes a decision based on two or more input signals.

logic gate — basic computing unit

The new processor uses advanced logic to distribute power between the different parts of the phone.

Common collocations
  • logic gate
  • logic board
  • circuit logic
  • processor logic
  • software logic
  • logic error
Synonyms
  • circuitry

    refers to the physical electronic components; more hardware-focused

  • computational rules

    more explicit but less common in everyday tech writing

Grammar Patterns

logic + noun (attributive use)

the logic of + noun phrase

Usage Note

In computing, 'logic' refers both to the physical arrangement of electronic parts (hardware logic) and to the rules written in code (software logic). Often used in compound nouns such as 'logic gate', 'logic board', and 'logic circuit'.

Common Mistakes

I need to fix the logic of this computer.
I need to fix the logic of this program.
'logic' in computing usually refers to the system or program design, not the physical computer itself.

Word family

  • logical
    adjectiveB1
  • logically
    adverbB2
  • illogical
    adjectiveB2
  • logician
    nounC1
  • illogically
    adverbC1

Synonym discussion

Sense: noun/1

All four words describe the mental process of reaching conclusions, but they differ in scope and context. 'Reasoning' is the broadest term — it describes the step-by-step mental process itself ('His reasoning was hard to follow'). 'Logic' focuses on the structural soundness of that process; an argument can follow logic even if the premises are false. 'Rationale' is more formal and refers to the stated reasons behind a plan or policy, often in business or government ('The rationale for the new tax was never explained clearly'). 'Sense' is the most informal and conversational, usually appearing in phrases like 'make sense' or 'common sense'. 'Justification' implies that someone is defending a position after the fact, often against criticism. Example: 'The logic of the argument was clear, but the politician's rationale did little to justify the cost.'

reasoning ↗rationale ↗sense ↗justification ↗

Common collocations

Nouns

Adverbs

Phrases

  • by the same logic
  • the logic behind
  • the logic of
  • according to the same logic
  • with compelling logic

Prepositions

Etymology

GreekLatinFrenchEnglish

The word 'logic' comes from the Greek word 'logikē' (λογική), meaning 'the art of reasoning'. This was formed from 'logos' (λόγος), which had many related meanings including 'word', 'speech', 'reason', and 'thought'. The term was first used by Greek philosophers such as Aristotle to describe the study of correct reasoning. It passed into Latin as 'logica' and then into English through French in the 14th century. Originally used only for the philosophical discipline, the everyday meaning — a sensible way of thinking — developed later, and the computing sense emerged in the 20th century with the rise of digital electronics.