Question

How does Polonius show his foolishness? Is the King/Queen convinced by his arguments?

Answer 1

In Hamlet, when Polonius is hidden behind the curtain and hear Gertrudis think perceive she is in danger, so when he starts to scream crying for help, Hamlet think he is Claudius and stabs him after discover the curtain; is at this moment when Polonius shows his foolishness, and in other scene, the king/queen is finally convinced by his arguments, boasting his espionage skills.