Revenge
The morality of revenge has been a source of discourse for years, and as revenge is one of the key themes of the play, a lot of debate has been made over it.[34] Hieronimo's pursuit for revenge and subsequent scheme is open to moral based judgement, but the question many scholars face is whether the responsibility and fault of Hieronimo's desire for revenge belongs solely to him. In one theory, Steven Justice proposes that the fault lies not in Hieronimo, but rather in the society at the time.[34] It is argued that Kyd used the revenge tragedy to give body to popular images of Catholic Spain.[34] Kyd tries to make Spain the villain in that he shows how the Spanish court gives Hieronimo no acceptable choice. The court turns Hieronimo to revenge in pursuit of justice, when in reality it is quite different.
Some critics claim that Hieronimo's attitude is what central Christian tradition calls the Old Law,[34] the Biblical notion of an "eye for an eye". Hieronimo's passion for justice in society is revealed when he says, "For blood with blood shall, while I sit as judge, / Be satisfied, and the law discharg'd" (III.vi.35–36).
Murder and death
The nature of murder and death, performed and as natural phenomena, is also questioned. Smith considers how the decade in which the play is set, is relevant to its mentionings of hangings, murders, and near deaths throughout.[35] Multiple characters are killed or nearly killed throughout the play. Horatio is hanged, Pedringano is hanged, Alexandro is nearly burnt at the stake, and Villuppo is assumed tortured and hanged. Kyd consistently refers to mutilation, torture, and death, beginning early in the play when the ghost of Don Andrea describes his stay in the underworld: "And murderers groan with never killing wounds, / And perjured wights scalded in boiling lead, / And all foul sins with torments overwhelmed" (I.i.68–70). He vividly describes in these lines as well as others the frequency of murder and torture in the underworld. Murder and death make up the tragedy theme that holds true through the last scene of the play.
Social mobility
Another theme is social mobility—characters such as Lorenzo and Pedringano are driven by their ambition and desire for more power. Pedringano especially so as he is a servant, belonging in the lowest rank of the hierarchy. His efforts to curry favor (and go beyond his 'place') with Lorenzo leads to his resulting downfall as he is barred from social mobility, a mere tool in the end.
In addition to that, Hieronimo and his family are labeled as a "middling sort" by many scholars.[36] Essentially the 'middle class,' Kyd establishes a situation in which conflict between Hieronimo's household and the nobility is inevitable as the middle class is seen as a threat, one that is pressing up on the aristocrats.[36] This is evident in scenes such as the resulting competition from the 'middling sort' Horatio and Lorenzo, the King's nephew.
Scholars cite oeconomia as the philosophy Kyd is adhering to in the play.[36]
