In A Doll's House, who is the tragic hero, and what is the tragic hero's fatal flaw or hamartia?
Nora Helmer is the heroine in the drama, and several elements of tragedy can be identified in her life; however, Nora is not a tragic heroine in the classical tradition. She is not destroyed by a fatal flaw in her own character. At the play's conclusion, in fact, Nora demonstrates tremendous courage as she takes control of her life and leaves her miserable sham marriage. Nora chooses an authentic life for herself, and the play ends with the suggestion that she will prevail through her strength and determination.
Aristotle's concept of hamartia means more than a "fatal flaw" in a character. It also can refer to a character's error in judgment, and this definition definitely does apply to Nora. Throughout their marriage, Torvald had treated Nora with condescension, as if he were dealing with a frivolous, irresponsible child. He had ruled over their household, controlled the finances, and directed her every daily activity.
For years, Nora had tolerated Torvald's behavior and accepted her role in their marriage. Furthermore, she once had forged her father's signature to a bank loan to obtain the money necessary to save her husband's life when he had fallen seriously ill. For years afterward, Nora had struggled to pay off the loan with money she scrimped from her household funds, living in fear that her crime might be discovered.
Nora had lived this unhappy life for one reason: Despite everything, she believed her husband loved her. This was her error in judgment, and because of it, she had endured Torvald's demeaning treatment and had lived in terrible fear for many years. Nora's error in judgment had consigned her to a life of frustration and lack of fulfillment. She had almost lost her own identity.
At the conclusion of the drama, Nora is forced by circumstances to tell Torvald about the bank loan, what she had done and why. When Nora has unburdened herself, her husband expresses no gratitude for the sacrifice she had made out of love for him, nor does he feel any concern for Nora's being punished for having broken the law. Instead he is quite angry at Nora for putting him in a bad situation; he worries about his own reputation.
Torvald's selfish behavior opens Nora's eyes to the truth. Her husband does not love her at all; to Torvald, she is nothing more than a "doll" playing her role in their "doll house." When she realizes that she had misjudged Torvald's character, Nora leaves her home and her marriage. She will not stay with an arrogant, selfish man who does not love her or respect her unselfish love for him.
The concept of a "tragic hero" derives from Aristotle's understanding of Greek tragedy. Ibsen's A Doll's House is not a Greek tragedy, and thus, it does not really follow the pattern discussed by Aristotle. While Nora is the protagonist of the play, she is not a "tragic hero."
The concept of "hamartia" is a Greek term mean an "error", deriving from the Greek verb "hamartein" meaning to err or miss, specifically in the sense of an arrow missing its target. In tragedy, this means an act that sets a character on the wrong path, and which, like an arrow shot from a bow, cannot be taken back.
In the case of Nora, one could argue that forging her father's signature was precisely this sort of irrevocable act that sets events on a course that inevitably lead to disaster. However, the ending of the play isn't really tragic. Nora's new understanding of herself and her life lead her to leave her marriage, but most viewers see this as a positive step rather than something that evokes "fear and pity."
The main issue here is that Ibsen is writing modern bourgeois drama rather than Greek tragedy, and thus the critical vocabulary developed to describe Greek tragedy really is not applicable.