The mob has many heads, but no brains.

The saying scorns a crowd as numerous yet irrational. It contrasts the many individual heads in a mob with an alleged absence of collective judgment, reason, or thoughtful direction.

It warns that numbers do not guarantee wisdom, but its image of a group as mindless is dismissive. It may therefore unfairly reject legitimate public concerns, agitation, or decisions as mere crowd feeling rather than deliberation.

Use it to criticize a crowd, mass movement, or group decision considered impulsive and poorly reasoned. Because it can insult participants and dismiss legitimate concerns, it is suited to polemical or cautionary remarks rather than neutral description.