Deception, Lies, and Hypocrisy
The central theme lying at the heart of the narrative of Ghosts is the long-term effects of keeping secrets and concealing truths. The epicenter of this theme is Mrs. Alving’s lifelong attempt to construct a myth about the true nature of her husband, the Captain, through a tapestry of lies and deception. Those lies in the name of keeping the real truth a secret eventually perpetuate themselves to the point that they are passed like a virus to the next generation, linking symbolically with the syphilitic strain that has the same degenerative effect. And, to a lesser extent, the Pastor's extreme hypocrisy dooms both the person he professes to care about—Mrs. Alving—and eventually himself, for as he endeavors to save his reputation, he ends up supporting a devilish trickster and a brothel.
Duty
It seems like every character has at least one speech about the importance of duty. All this attention to carrying out the duties that are expected of one leaves very little time for carrying out what one actually wants or needs. This contraction of time put aside to pursue selfish pleasures invariably obstructs the ability to achieve self-awareness. The person who results from these circumstances is a living ghost: a being without form or structure, insubstantial and indistinct.
Generational Degeneration
This theme is otherwise known as "the sins of the father," and in the case of Osvald, this is both literally and figuratively true. Osvald’s collapse into moral dissolution that reflects the bad choices previously made by his father has nothing to do with the transmission of the syphilis virus. The genetic strain is the symbol here: Osvald is really infected by generational immorality. This theme is manifested in a pervasiveness sense through Regina’s maternal duplication and the Pastor’s almost paranoid fear of the potential of radicalism to "infect" traditional views on morality and values. The unfolding of this theme offers insight into Ibsen's belief that some families just seem genetically predisposed to a lack of moral character.
Reputation
Reputation is very important to Mrs. Alving and to Manders, both of whom maintain a web of hypocrisies and lies to appear a certain way to the rest of the world. Mrs. Alving doesn't want to step out of line in society even though she is unhappy, so she returns to a loveless marriage. Even after her husband behaves poorly, she seeks to burnish his reputation rather than revealing the truth, which leads to trouble for her son and for herself. And Manders cares more about his reputation than actual people, leading him to become blind in the face of actual malevolence and manipulation—Engstrand—and to excoriate examples of an authentic and loving way of life -Osvald in Paris.
