手て前まえ定じょう規ぎ

Meanings

1

noun

self-serving logic; convenient reasoning

Refers to reasoning that is twisted to suit one's own interests or convenience, often used critically.

彼かれの言いい分ぶんは手て前まえ定じょう規ぎで、まったく説せっ得とく力りょくがない。
His argument is self-serving and completely unconvincing.

自じ分ぶん勝かっ手て
自分勝手 describes selfish behavior in general, while 手前定規 specifically refers to self-serving logic or reasoning.
ご都つ合ごう主しゅ義ぎ
ご都合主義 is a broader term for opportunism or expediency, whereas 手前定規 focuses on the act of twisting logic to fit one's own convenience.

Built from

手て前まえ+定じょう規ぎ

Etymology

Compound of 手前 (oneself) and 定規 (ruler, standard), literally meaning 'one's own ruler,' implying a standard that is conveniently adjusted to suit oneself.