noun
impractical theory; empty theory; academic discussion divorced from reality
A yojijukugo used to criticize ideas or arguments that are logically consistent but lack practical application or real-world grounding. Often carries a negative connotation of being out of touch.
彼の提案は空理空論に過ぎず、現場では全く役に立たない。
His proposal is nothing but empty theory and is completely useless in the field.
空理空論を振り回すより、まずは実行してみることが大切だ。
Rather than brandishing impractical theories, it's more important to try putting things into practice first.