所以

• Reading: ゆえん
• Romaji: yuen
• Kanji breakdown: 所 (sho/toko) — that which, place; 以 (i/motte) — by means of, reason
• Pronunciation: /jɯe̞n/

Meaning

Reason; grounds; the basis for why something is so.

A formal, literary noun used to express the underlying reason or grounds for something. Typically appears in the pattern 〜の所以 (the reason for...) or 所以に (for that reason). Considerably more formal and classical in register than わけ or 理由. Encountered in formal essays, philosophical writing, and literary prose. Rarely used in spoken language.

Examples

1. それが彼の偉大さの所以だと多くの人が認めている。 Many people acknowledge that this is the very reason for his greatness.
2. 伝統が受け継がれる所以は、その実用性にあるのだろう。 The reason traditions are passed down likely lies in their practicality.
3. この法律が廃止された所以を理解するには歴史的背景が必要だ。 Understanding the reason this law was abolished requires historical context.

Usage Guide

Context: literary, philosophical, academic, formal essays

Tone: neutral

Origin & History

Compound of 所 (that which, place) and 以 (by means of, reason). The combination means 'that by which' or 'the basis for', a classical construction expressing grounds or reasoning.

Cultural Context

Era: Classical

Generation: Adults

Social background: Educated