人云亦云

rényúnyún
  1. to say what everyone says (idiom)
  2. to conform to what one perceives to be the majority view
  3. to follow the herd

CEDICT

to say what others say; to follow the herd

Wiktionary

別人什麼自己隨聲附和形容沒有獨立見解盲從跟隨

重編國語辭典

別人什麼自己隨聲附和表示沒有自己主見

維基詞典

Entry Composition