What does rationality mean?
Rationality means thinking, judging, or acting in a way that is grounded in reason and logic rather than impulse, prejudice, or emotion. People may praise someone's rationality when they show calmness, intellectual discipline, and the ability to assess evidence; they may criticize a conclusion as irrational when it ignores facts or relies on prejudice. The word can also describe the quality of a decision: a plan, policy, or argument can be rational even when its outcome is uncertain or unsuccessful. Rationality does not mean being emotionless or always following majority opinion, since meaningful decisions often require empathy, experience, and judgment as well as logic. In everyday discussion, it is a useful term for distinguishing careful thought from knee-jerk reaction, while in philosophy and related fields it can refer more specifically to the role of reason in knowledge, ethics, or decision-making.
nounRationality is the quality of being based on reason, logic, and careful thought rather than impulse, emotion, or prejudice. It can also refer to the soundness and consistency of a decision or argument.
- The quality of thinking or acting in a logical, reasoned, and intellectually disciplined way.
- The degree to which a decision, argument, or judgment is sound, coherent, and based on relevant evidence.
"She approached the dispute with calm rationality, examining the evidence before reaching a conclusion."
"The debate was conducted with more rationality than either side had shown in its earlier statements."
"In an emergency, rationality is only useful when it is combined with decisive action."
The plural is grammatically standard but uncommon, since rationality is normally used as a mass or abstract noun.
"The authors compared different moral rationalities across competing legal traditions."
Rationality is the quiet discipline of asking what would make sense—and refusing an answer simply because it feels good.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does rationality come from?
Rationality was formed in English from the adjective rational and the suffix -ity, meaning the quality or state of being something. Both elements connect it to the Latin root ratio, meaning reason, relation, or method of calculation, which also underlies ration, rationale, and rationalize. The word developed as a term for reason-based thinking and later came to be used in philosophical discussions of reason and conduct.
Related word forms
How rationality is actually used
Rationality is generally neutral and formal, but it can sometimes imply a contrast with emotion, intuition, prejudice, or excessive skepticism. It is not restricted to either British or US usage.
Easily confused with rationality
Rationality is the general practice of thinking and deciding on logical grounds, whereas rationalism is a philosophical position emphasizing reason as the principal source of knowledge.
Reason is the faculty or process of thinking and reasoning, while rationality more specifically emphasizes the quality of being logical, balanced, and guided by reason.