Hamlet's tragic flaw is his inability to consolidate his thoughts and actions. Hamlet is plagued by indecisiveness. He mulls the possibilities endlessly in his mind, delaying his decision, making action nearly impossible. When Hamlet finally takes action, it is often rash, careless, and without thought. One must ask what is the point of his reasoning and considering, if it has no bearing on his final action.

A tragic flaw is something that makes the hero imperfect. It is a small defect that makes the character recognizable as human, but it is important enough that it leads to the downfall of the character. The importance is that the external factors don't cause the character's downfall, but the character's own flaw. Hamlet is aware of such a thing among men, and he even describes how the tiny defect can often destroy the person,

So, oft it chances in particular men...