Acknowledged as one of Shakespeare's greatest tragedies, Hamlet centers on the actions of a young Danish prince called upon by a ghost to avenge his father's murder at the hands of his uncle, King Claudius. For scholars the central issues of the play have intersected in the character of Hamlet, specifically in regard to the themes of madness and revenge that he personifies. Some critics have been concerned with Hamlet's apparent plunge into madness during the course of the play, and whether this insanity is real or feigned. Others have concentrated on Hamlet's revenge for his father's death—which directly and indirectly leads to the demise of nearly all of the major characters in the drama, including Hamlet himself—asserting that it raises the moral question of whether or not the prince is basically good or evil in his intentions. Further subjects of interest to commentators have included assessments of the play's female characters, Queen Gertrude and Ophelia, and their often ambiguous motivations, as well as the nature of the play's varied symbolism and imagery.
The question of madness in Hamlet has consistently intrigued modern scholars, many of whom have placed this subject at the center of their interpretation of the play by focusing on the compelling and enigmatic figure of Hamlet himself and the precise nature of his alleged insanity. Some critics, such as Paul Jorgensen and Theodore Lidz, have taken a psychological approach to the issue. For Jorgensen, Hamlet is the victim of a pathological grief that manifests itself in his melancholia. The critic diagnoses this melancholy in Freudian terms as repressed rage diverted toward himself instead of his enemies, and sees the movement of the play as leading to a resolution of this perturbed state. Lidz complicates the issue by contending that Hamlet, though he suffers from certain real forms of madness, nevertheless retains his keen intellect and at times only pretends to be insane in order to thwart and baffle those who would prevent him in his quest for revenge. P. J. Aldus has observed Hamlet's madness from multiple perspectives, ranging from the clinical, including an analysis of his paranoid schizophrenia, to the mythic and archetypal, particularly in the relationship between the prince's insanity and his roles as poet, dramatist, actor, and reflection of Shakespeare. Anna K. Nardo, conversely, has asserted that Hamlet's madness derives from the impossibility of his situation; forced to avenge his father without harming his mother or tainting his honor, he escapes into insanity. Some commentators, however, such as Bernard Grebanier, deemphasize the importance of Hamlet's insanity, highlighting the prince's nature as kind, compassionate, and magnanimous. Still other critics have examined the political and cultural dimensions of madness in Hamlet. Duncan Salkeld has maintained that Shakespeare presents a paranoid world in the play, which projects his society's collective fears of subverted power and sovereignty, and Alison Findlay has examined madness as related to the instability of language and the subversive power of gender in the play.
The theme of revenge in Hamlet has also elicited much critical attention among contemporary scholars—primarily in terms of the Ghost's nature and Hamlet's moral culpability as the play's executioner. Eleanor Prosser has asserted that the ghost of what appears to be Hamlet's father is nothing more than a devil sent from hell to exhort Hamlet to perform evil acts in the name of revenge. Harold Skulsky has argued, however, that the Ghost leaves all decisions to Hamlet, forcing him to choose between his feelings of honor, responsibility, cowardice, and compassion. In addition, while many commentators have noted the primary source for the play as the so-called Ur-Hamlet—a revenge tragedy often attributed to the Elizabethan dramatist Thomas Kyd—all agree that Shakespeare pushed the bounds of the source material in his complex exploration of the revenge motif. In line with these modern assessments, Michael Cameron Andrews has observed that Shakespeare avoids didacticism by refusing to make any final judgment on Hamlet's guilt, while Harry Keyishian has seen the work as less equivocal, contending that Hamlet is basically good and is motivated more by his own moral integrity than the outside urgings of malevolent forces or an inner desire for destruction.
An increasing number of contemporary critics have turned their attention to the drama's supporting cast, especially its female characters Gertrude and Ophelia. The majority of commentators have seen Queen Gertrude as a weak, passive, and sentimental woman—an assessment represented by Baldwin Maxwell, who has noted that Claudius dominates her until the play's closing moments, when she drinks a poisoned cup of wine despite his protests. More recent investigations of Gertrude's character, such as that undertaken by Rebecca Smith, emphasize not her weakness, but her deep and tragic love for two men caught in mortal conflict with one another. The dilemma of choosing between two types of love is likewise reflected in much criticism of Ophelia. Robert Tracy, for example, has explored the conflicting imagery of sensual love and virginity surrounding her character, and has noted that when faced with the dilemma of demonstrating both her love for Hamlet and respect for her father's wishes, she flees reality, descending into madness and eventual suicide.
The varied nature of Shakespeare's imagery in Hamlet has additionally been a significant topic of interest to twentieth-century critics. Commentators have long observed the symbolism of disease, decay, and corruption that pervades the work and reinforces its themes. Kenneth Muir has noted, however, that Hamlet is not limited to the images of rottenness that represent the state of Denmark at the opening of the play. Muir has asserted that the play evokes a range of symbolism, including representations of sexuality and war and images from the theater, all of which complicate the play and emphasize its concern with the contrast between appearances and realities. The play's symbolism has also been explored by Henri Suhamy, who finds its imagery at once ambiguous, contradictory, and paradoxical—further proof of the play's protean nature, rich complexity, and enduring appeal to scholars and audiences.