Final answer:
Hamlet feels the need for evidence of Claudius's guilt to justify his actions and confirm the truth revealed by the ghost. He wants tangible proof before taking revenge.
Step-by-step explanation:
Hamlet feels that he must have evidence of Claudius's guilt because he wants to ensure that his actions are justified. The ghost of Hamlet's father has told him that Claudius murdered him, but Hamlet wants to confirm this before he takes any drastic measures. He wants tangible proof to convince himself and others before he proceeds with his plan for revenge.