Translation guide
The quality of being illogical, unreasonable, or not based on clear thought. In Japanese, this concept is often expressed through nouns describing the state, adjectives for describing actions or people, and set phrases highlighting contradiction or lack of reason.
Referring to irrationality as an abstract concept or characteristic, often in philosophical, psychological, or analytical contexts.
The most direct and common translation for 'irrationality' as a noun. It means lack of reason or logic, and is used in both formal and everyday contexts.
彼の行動の不合理さには驚かされる。
I am surprised by the irrationality of his actions.
A more formal or academic term for irrationality, often used in discussions of logic, economics, or philosophy. It emphasizes the absence of rationality as a property.
人間の非合理性を理解することが経済学の鍵だ。
Understanding human irrationality is key to economics.
Often translated as 'unreasonableness' or 'irrationality', but carries a stronger nuance of something being unfair, absurd, or not making sense in a frustrating way. Commonly used for situations or rules.
その規則の理不尽さに皆が抗議した。
Everyone protested the irrationality of the rule.
Describing specific instances of thinking or acting without reason, often in psychology or everyday situations.
A phrase meaning 'irrational thought'. It is neutral and can be used in both casual and formal settings.
彼は非合理的な考えに囚われている。
He is trapped by irrational thoughts.
Refers to 'irrational behavior' with a nuance of unfairness or absurdity. Often used when someone acts in a way that defies common sense and causes trouble for others.
彼の理不尽な行動に周りは困惑した。
People around him were bewildered by his irrational behavior.
Specifically 'irrational belief', often used in cognitive therapy or psychology contexts.
認知療法では不合理な信念を修正する。
Cognitive therapy corrects irrational beliefs.
Expressing that a thing, action, or person lacks reason or logic.
The standard adjective meaning 'irrational'. It directly modifies nouns and is widely understood.
それは不合理な要求だ。
That is an irrational demand.
Adjective form emphasizing unreasonableness and often unfairness. It is very common in spoken Japanese when complaining about situations.
理不尽な理由で断られた。
I was rejected for an irrational reason.
More formal and analytical adjective, often used in academic or technical descriptions.
非合理的な意思決定は避けるべきだ。
Irrational decision-making should be avoided.
Highlighting the nonsensical or contradictory nature of something, often with emotional emphasis.
Means 'absurdity' or 'irrationality' in a philosophical or existential sense. It implies a lack of logical coherence in the world or a situation, often used in literature and drama.
人生の不条理を描いた小説。
A novel depicting the irrationality of life.
Literally 'contradiction'. It can express irrationality when something contradicts itself or logic. Very common in everyday language.
不合理 (fugōri) is the most general term for irrationality, focusing on lack of logic. 理不尽 (rifujin) adds a strong nuance of unfairness or unreasonableness that affects someone negatively. 非合理的 (higōriteki) is more formal and often used in academic contexts to describe something not based on rationality.
In casual conversation, Japanese speakers rarely use abstract nouns like 不合理性. Instead, they often use adjectives like おかしい (strange/irrational) or phrases like 理屈に合わない (it doesn't make sense). Using the noun forms can sound overly formal or stiff.
彼の決断の不合理さは明らかだった。
The irrationality of his decision was obvious.
彼女はその規則の理不尽さに我慢できなかった。
She couldn't stand the irrationality of the rule.
His argument is full of irrationality (contradictions).