背理

• 読み: はいり
• ローマ字: hairi
• 漢字の分解: 背 (hai/se/somu) — back, go against, betray; 理 (ri/kotowari) — reason, logic, principle
• 発音: /haiɾi/

意味

Absurdity; contradiction; irrationality. A conclusion or premise that contradicts reason, logic, or established truth.

A formal, philosophical term. Most often appears in 背理法 (proof by contradiction, reductio ad absurdum) — a logical method that assumes the opposite of what one wants to prove and derives a contradiction. Also used more broadly for irrational or self-defeating reasoning in general discourse.

例文

1. 背理法を使えば、素数が無限に存在することを証明できる。
2. 彼の主張には根本的な背理が含まれており、論理的に成立しない。
3. 自由を守るために自由を制限するという議論は、背理に陥りやすい。

使い方ガイド

場面: mathematics, philosophy, logic, argumentation

トーン: analytical

起源と歴史

Compound of 背 (hai, to go against/turn one's back) and 理 (ri, reason/principle/logic). Together they convey the sense of turning against or contradicting the principles of reason.

文化的背景

時代: Classical

世代: Adults

社会的背景: Educated