Is Hamlet crazy, or is everyone else just suspicious? Give evidence from the text to prove if Hamlet is crazy, or if Hamlet is not crazy.

Madness, real and pretend, is a recurring motif in Shakespeare’s Hamlet. The title character, Hamlet, tells his friends after meeting the ghost of his father and learning his father was murdered by his uncle, "I perchance hereafter shall think meet / To put an antic disposition on" (1.5.171-172). Hamlet is warning them that he plans to behave strangely. While he doesn’t say why it is assumed that he plans to act like he is crazy so that King Claudius is distracted and fails to notice he is planning revenge.
Later, Ophelia tells her father, Polonius, about Hamlet’s strange visit to her closet. She describes him as entering with his shirt undone, his socks around his ankles, his knees knocking together, and with no hat on his head. To add to the strangeness of the visit she reports Hamlet only grabbed her by the wrist, then let go and backed away, saying nothing. He seems to be mad in this scene, and she immediately tells her father, who assumes he is lovesick. This scene seems to accomplish what Hamlet may have hoped—instead of being suspicious of his actions Polonius is focused on his behavior being the result of a broken heart. Later on, the King and Queen summon childhood friends of Hamlet’s to learn what has caused his “transformation.” While Hamlet is implementing his plan to prove Claudius’s guilt with the play the actors will perform Claudius is distracted by Hamlet’s “madness,” allowing him to plan without notice.
In another scene, Hamlet has an absurd conversation with Polonius that finds Hamlet using wild puns and acting eccentrically. After his encounter, Polonius still believes the behavior is caused by Ophelia’s break up with him, though he may be starting to think it is more than that, saying "Though this be madness, yet there is method in't" (2.2.205-206). Midway through Act 3, Ophelia exclaims after a brutal confrontation with the unstable Hamlet, "O, what a noble mind is here o'erthrown!" (3.1.150).
Hamlet’s behavior continues to deteriorate throughout the play and some people believe that while he intended to act like he is crazy at the start, he may have literally lost his sense of reason due to the pressure of planning revenge and the sadness of losing Ophelia. Throughout the play, though, right up until the end, Hamlet’s soliloquies are beautiful and well-reasoned; they are measured attempts to show his growing determination to enact his revenge. This is why it seems likely that Hamlet was indeed just playing mad in order to be able to fulfill the promise he made to his father’s ghost and avenge his father’s murder.