(I was updating the kotowaza index when I discovered that I had doubled my use of the saying 目から鼻へ抜ける, so this “extra” post is intended to make up for the gap. Please enjoy!)

理屈上手の行い下手
(Rikutsu jouzu no okonai beta; “Good at theory, bad in execution”)

Definition:

When someone is good at reasoning or theorizing, but unable to put that theory into practice. All talk, no results.

Breakdown:

This kotowaza comprises two parallel noun phrases, joined by the associative particle の (no). The primary noun of the first half is 上手 (jouzu), “skillful,” attached to and specified by the noun 理屈 (rikutsu), “reasoning,” often with the nuance of petty rationalization rather than deep rigor. The primary noun of the second half is 下手 (heta), “unskilled,” attached to and specified (and changed phonetically) by the verb 行う (okonau), “to carry out [an action],” taking conjunctive form in order to act as a noun.

Notes:

The content and phrasing of this saying are both pretty similar to another one that we’ve seen before.

Example sentence:

「一年生の時は教授たちは皆理屈上手の行い下手だろうと馬鹿にしてたけど、先生のラボで働くようになってから味方が変わったよ」

(“Ichinensei no toki wa kyouju-tachi wa minna rikutsu jouzu no okonai beta darou to baka ni shiteta kedo, sensei no rabo de hataraku you ni natte kara mikata ga kawatta yo.”)

[“When I was a freshman I thought all the professors were good at theory and bad at execution, but my views have changed since I went to work in the lab.”]