Here's what the play suggests:
Arguments for Banquo's ghost being real:
* Multiple witnesses: Macbeth isn't the only one who sees the ghost. The other guests at the banquet also see him, and they are visibly shaken.
* Macbeth's reaction: Macbeth reacts to the ghost with fear and guilt, suggesting he believes what he's seeing.
* Supernatural themes: The play is rife with supernatural elements, including witches and prophecies, making the possibility of a ghost seem plausible.
Arguments for Banquo's ghost being an illusion:
* Macbeth's guilt: Macbeth is deeply troubled by his actions, particularly the murder of Banquo. His guilt and paranoia could be manifesting in hallucinations.
* The ghost's purpose: The ghost acts as a powerful symbol of Macbeth's conscience, serving as a constant reminder of his crime and the consequences of his ambition.
* Macbeth's state of mind: The play suggests Macbeth is losing his grip on reality. His conversations with his wife and his paranoia about the witches could be signs of mental instability.
Ultimately, the play leaves the question open to interpretation.
Shakespeare's ambiguity allows the audience to consider:
* Is Macbeth's conscience so powerful that it can conjure a ghost?
* Or is the ghost a real entity, sent to haunt him for his crimes?
The question of Banquo's ghost's reality serves to highlight the power of guilt, the consequences of ambition, and the fragility of the human mind.