What does 一概に (いちがいに, ichigaini) mean?

一概(いちがい)にどちらが良(い)いとは言(い)えない。

You can't simply say which one is better.

若者(わかもの)を一概(いちがい)に怠(なま)け者(もの)だと決(き)めつけるな。

Don't hastily brand young people as lazy.