Morality
An implicit question within the plot of the play is, "Is Lizzie's murder of her parents justified?" While murder is undoubtedly a punishable crime no matter the context, playwright Sharon Pollock seeks to complicate the moral rubric that we typically associate with murder, and particularly with Lizzie Borden's crime, which is often upheld as one of the more unthinkable murders in history. Throughout, we are led to empathize with Lizzie's plight: her abuse at the hands of her father, her being denied economic freedom, and her being all but excommunicated from her family when she fails to marry.
Pollock uses the stage, a forum in which audiences are led to empathize with complex characters, to try and show the ways that morality is highly subjective and sometimes arbitrarily upheld. While Lizzie's murderous acts can hardly be called "moral," they certainly spring from disempowerment and disenfranchisement at the hands of her parents. Pollock seeks to show just how complicated Lizzie's moral landscape is in the moments leading up to her parents' deaths.
Family
Lizzie Borden is portrayed as the victim of a family that does not care for or nurture her. She wants so badly to be loved and nurtured by her father, but he is distracted, inconsistent, and sometimes abusive. Her stepmother is cruel and does not understand Lizzie's more wayward, rebellious spirit, seeking instead only to compete for Mr. Borden's financial and personal attention. Lizzie's uncle is a lascivious and greedy man who seeks to have financial control over her. Finally, Lizzie's sister Emma is loyal but weak-hearted, never seeking to get close with or understand her sister. In the universe of the play, the family unit is one in which Lizzie feels completely alienated and isolated. It is from this context that it becomes conceivable that Lizzie would even be capable of the horrific act at the center of the play, the murder of her parents. The play explores the taboos of the unhappy family, the fact that some families harm their members, rather than nurturing and helping members thrive.
Truth
The Actress asks Lizzie “Did you do it?” and tries her hardest to get any truth out of Lizzie about the murder of her parents. Lizzie's sister, Emma, also is fixated on the question of whether Lizzie actually killed their parents, and asks her many times. While Lizzie wants to playact the murders as if they happened, she never quite cops to whether she committed them, and the play begins after she has been acquitted of the crime by the jury that tried her. Thus, the question of truth becomes thematically central, as we try to piece together whether or not Lizzie is being truthful, or whether she is simply leading everyone on, playing games.
Additionally, Lizzie's mental state leading up to the murders is portrayed as a state of psychic break in which she herself is somewhat alienated from reality. She struggles to maintain her grasp on the truth of her surroundings, sent into a near-psychotic fury by her post-traumatic response to her family's mistreatment of her. Within the bounds of the reenactment, Lizzie loses grasp of the truth and her own sanity, which leads her to commit the violent act.
Performance
There is a play within the play itself. Lizzie's confidant, the Actress, plays her in their performance of the events leading up to Lizzie's parents' murders. While the Actress performs as Lizzie, Lizzie plays Bridget, the maid. Pollock's choice to stage the events of the murder in a performance within the play itself further alienates the audience from the objective truth of the scenario. The performance allows the audience to empathize with Lizzie, to understand her perception of how everything happened, which aligns us with her, while also making the entire event that much more mysterious. Performance is a means through which Lizzie can both sharpen and obscure her experience, turn it into something that is at once understandable and hazy, mediated by other factors and by the artifice of "the stage."
The Bell-Jar Effect
Lizzie's insanity is born out of the fact that she is completely cut off from the outside world. Having elected not to marry, Lizzie has confined herself to the family home, which has only limited her freedoms. In choosing not to cede all of her power to a husband, Lizzie has effectively chosen to cede all of her power to her father. This has a dizzying effect on Lizzie, who becomes completely out of touch with the world at large, leading her to commit the atrocious murders.
Pollock describes Lizzie's alienation from the world outside as "the bell-jar effect," writing, "For Lizzie, a bell-jar effect. Simple acts seem filled with significance. Lizzie is trying to fulfill other people's expectations of 'normal.'" On the day leading up to the murders, Lizzie is completely trapped in her own "bell jar," trying desperately to connect her lived reality to the reality of those around her.
Being a Lady
One of the things that separate Lizzie from her family's expectations of her is the fact that she is bad at being a society lady. Lizzie's forthrightness and boldness are not considered "lady-like," and this is part of what everyone resents about her, including her own father. While there is an affection between Lizzie and Mr. Borden, he is also wary of her more androgynous traits. In a stage direction, when Mr. Borden is trying to level with his daughter about being better behaved, Pollock writes, "She smiles at him, there is affection between them. She has the qualities he would like in a son but deplores in a daughter."
This failure to live up to others' expectations of her own femininity causes Lizzie a great deal of anguish. In several monologues she discusses the fact that, growing up, she always had scabs on her knees from being outside, which others told her made her fail to live up to the way a lady ought to behave. This expectation plagues her in adulthood, as she fails to live up to the standards of a woman of her class, remaining unmarried and wanting to have a career and control of her own finances.
Abuse
Another element of Lizzie's life that leads the audience to better understand Lizzie's plight is the fact that she lives in an abusive household. Her father hits her several times, strikes a hatchet into the table in rage, and kills her beloved pet pigeons in front of her. These acts of violence against Lizzie are what make her so angry with her family and lead her to become violent towards them. In staging Lizzie's abuse, Pollock shows the audience that Lizzie's acts, while far more violent than abuse, are partially retaliatory.