There is ongoing debate about Macbeth's status as a "tragic hero." Shakespeare makes us feel pity for Macbeth in all his confusion as he is easily influenced (by Lady Macbeth and the weird sisters). He recognizes that the witches words "cannot be ill, cannot be good" (I.iii) but cannot interpret them except to believe that "nothing is / But what is not" as his "vaulting" ambition will ultimately render him irrational.
This already foreshadows the effect that the witches will have on Macbeth as he tries to live up to his wife's expectations and be a "man" and realize the full extent of his rise to power.
In Act I, scene vii we see Macbeth considering his options. It it apparent that his main fear when killing Duncan is whether he will be discovered or damned and whether the glory on earth would be worth it. Rather than dismissing it outright, he admits that it is his ambition, his fatal flaw, "which o’erleaps itself."
Knowing Macbeth's now fragile state as he strives to satisfy his own desires, his wife's wishes, the witches' prophesies and his conscience the dagger scene becomes all the more tragic. Shakespeare has cleverly built up to this point to ensure that Macbeth cannot fight the forces that envelop him. The soliloquy shows the audience Macbeth's unstable mind and inability to judge.
Banquo , in Macbeth's home significantly mentions the three sisters which Macbeth claims to "think not of them"(II.i), clearly an untruth as, as soon as Banquo has retired, Macbeth hallucinates and can't quite decide whether it is a "false creation. " There is a contrast here between Macbeth's feelings towards the witches (and how "witchcraft celebrates" ) and Banquo's troubled sleep.
Macbeth, entranced, has an opportunity to see the illusion for what it is but the bell, his signal, prompts him to think no further about it - "I go and it is done..(II.i.)" This cements Macbeth's fate and shows how he is completely at the mercy of Lady Macbeth, his driving force and the witches.
The daggers will again torment Macbeth as he finds that he forgot to leave them behind on murdering Duncan- adding to the previously figurative references to the so-called floating dagger. This further cements the belief that Macbeth is not responsible for his actions as Lady Macbeth then steps in to replace the daggers whilst Macbeth rants and fears that even the vast ocean cannot even "wash this blood."
The soliloquy itself then sets Macbeth up as powerless to fight the forces that surround him.
To show how the soliloquy seals Macbeth's "tragic hero" status, it is necessary to show why he is so confused. It is this very confusion that is responsible for the hallucinations.
Macbeth, having changed his mind, "We will proceed no further in this business"(I.vii) is persuaded by Lady Macbeth to go ahead with Duncan's murder as otherwise he is hardly a man: "When you durst do it, then you were a man." His emotions are thus very conflicted. We know he is prone to the extraordinary - he's married to Lady Macbeth who is eccentric, passionate and actually quite scary! She is however his "Greatnesse."
It makes sense then that the soliloquy reveals his bewilderment - thus rendering him a tragic hero- as Macbeth wants to be everything to Lady Macbeth, wants to meet her expectations and wants to satisfy his own "vaulting ambition"- thus exposing his fatal flaw.
The soliloquy suggests that Macbeth killing Duncan is preordained as the dagger presents itself with "the handle toward my hand." The "gouts" of blood that suddenly present and the reference to Hectate (the head witch) confound his confusion as he cannot stop; he is powerless against the forces. The dagger will drive him as if giving him the permission to commit Duncan to "heaven or to hell."
Macbeth is certainly dramatic and this soliloquy is particularly shocking to the audience. Macbeth is a noble character, rewarded by his king and celebrated by his countrymen but he is destined to fail as "witchcraft" interferes with the normal flow of his future and "thou marshall'st me the way that I was going." He has no choice in it!
The dagger may be an illusion at this point but it is a very real act he is about to perform. He is concerned about being discovered "hear not my steps" but as soon as the bell rings "I go, and it is done," it is as if there is no alternative because "the bell invites me."
Thankyou for answering, however, it wasn't quite the answer i was looking for. I wanted to know what specific parts of the 'floating dagger' soliloquy help contribute in presenting Macbeth as a tragic hero and not the soliliquy overall.