Shakespeare'sHamletprobably contains more soliloquies by the hero than any of Shakespeare's other plays. The contents of these soliloquies have been discussed for centuries. They certainly help in understanding what is going on inside Hamlet's mind--but Shakespeare, as a dramatist, had other ways of imparting this kind of information to his audience. Hamlet confides in Horatio and confides in his mother. He has conversations with Ophelia, Polonius, Rosencraantz, and Guildenstern. He doesn't really have to be talking to himself as much s he does. Soliloquies, like asides, threaten verisimilitude because people in real life do not generally talk to themselves, especially at such great length as the prince does inHamlet.
The famous soliloquy beginning with "To be or not to be" is not necessary to the play either as exposition or foreshadowing. What seems to have been Shakespeare's intention in writing all these long soliloquies for his hero was to characterize him as a man who thinks too much. We in the audience are to understand that we are eavesdropping on only a small portion of all his reflections, meditations, cogitations, speculations, recollections, and other mental processes. The soliloquies characterize him as a man who is by nature a deep thinker and who has become addicted to thinking as a result of his long years of study. This characterization is of special importance because it explains why Hamlet does not act decisively.
Many questions about Hamlet submitted to eNotes use the terms "indecisive" and "procrastinating." The biggest problems with this play have to do with why Hamlet fails to act, why he berates himself for not acting, why he feels shamed by the examples of Laertes and Fortinbras, why he keeps urging himself to obey his father's ghost's orders to kill Claudius for murdering him in his sleep in his garden. In order to be able to commit a murder, Hamlet would have to feel murderous rage, and his continual thinking inhibits his feelings, while his continual soliloquizing illustrates his continual thinking. Hamlet is a philosopher and a scholar who is called upon to take aggressive action in the real world and feels inadequate to do it. With all his thinking he is unable to understand himself.