noun
armchair plan; impractical plan; paper plan
A plan that looks good on paper but is unrealistic or impractical in reality. Often used critically.
wasei-eigo (Japanese-coined English), from paper plan
彼の提案はペーパープランに過ぎない。
His proposal is nothing more than an armchair plan.
その改革案は机上の空論
That reform plan was a paper plan, not just an armchair theory.