Originally Posted by
Saturnalia
Hamlet is completely sane, the problem is that he has become intoxicated with the thought of revenge. If anything he is a mad man using logic. He knows who he is. The Ghost of his father appeared to the guards as well and anything that may have been an hallucination was witnessed by the guards too, except for the occasion with the Queen. The fact that he unrelentlessly had his 'friends' executed is not something I would condemn or call insane, they had already stabbed him in the back with glee.
The problem comes in when he calously manipulates Ophelia, driving her further into madness, and unknowingly kills her father. These are not things a less reckless man would do. He commits these acts with only one thing in mind, revenge. Thus I would have to say on the whole sane, but vicariously insane.