rationality

rationality — noun

1. the quality of making judgments or decisions by thinking through facts and logic

1.nounB2
Definition

the quality of making judgments or decisions by thinking through facts and logic rather than acting on emotion or impulse

Example

The judge praised the committee for the rationality of their decision to fund only proven programs.

collocation: rationality of [decision/argument/approach]

Andrew questioned the rationality of spending half his salary on rent each month.

question the rationality of [something]

Common collocations
  • the rationality of [a decision/argument/approach]
  • question the rationality of [something]
  • act with rationality
  • a lack of rationality
  • maintain rationality
  • preserve rationality
Synonyms
  • reason

    broader term referring to the thinking ability itself ('the power of reason') rather than the quality of a specific decision

  • logic

    focuses on formal, step-by-step reasoning where conclusions follow necessarily from premises; slightly narrower than rationality

  • reasonableness

    emphasises fairness, moderation, and practical good sense in judgment, not just abstract logic

  • sense

    practical everyday good judgment ('common sense'); less formal and less intellectual than rationality

Antonyms

Grammar Patterns

the rationality of [noun phrase]

act with rationality

question the rationality of [noun phrase]

Common Mistakes

His rationality for leaving the company was the salary.
His rationale for leaving the company was the salary.
'rationality' means the quality of being rational, not the specific reason or explanation for an action.
She made a rationality decision.
She made a rational decision.
'rationality' is a noun; the adjective form 'rational' is used before a noun.

Word family

  • rational
    adjectiveB2
  • rationally
    adverbB2
  • rationalize
    verbC1
  • rationalization
    nounC1
  • irrational
    adjectiveB2
  • irrationality
    nounC1
  • rationale
    nounC1

Synonym discussion

Sense: noun/1

Rationality is the quality of thinking based on facts and clear reasoning rather than emotion. Reason is a broader term for the thinking faculty itself ('the power of reason'), whereas rationality describes the quality of a particular decision or argument. Logic is narrower: it refers to formal, step-by-step reasoning where conclusions follow from premises by necessity — a rational decision may be 'logical' but a logical argument can lack practical wisdom. Reasonableness adds the idea of fairness, moderation, and common sense; you can be perfectly logical yet unreasonable if you ignore human needs. Sense (as in 'common sense') is the most everyday term, focusing on practical, experience-based good judgment rather than formal reasoning. For example, a chess player's move can be rational and logical, while a parent's flexible rule may be reasonable and sensible without being strictly logical.

reason ↗logic ↗reasonablenesssense ↗

Common collocations

Nouns

Adverbs

Phrases

  • a lack of rationality
  • with rationality
  • without rationality
  • an element of rationality

Prepositions

Etymology

LatinFrenchEnglish

The word comes from Latin 'rationalitas', meaning 'the quality of being reasonable', which is formed from 'rationalis' ('of or belonging to reason'). 'Rationalis' comes from 'ratio' ('reason, calculation, reckoning'). The word entered English in the early 1600s through French 'rationalité'.