Darkness
The Playboy of the Western World approaches the question of darkness from several different angles. At the top of the play, the literal darkness of the nighttime creates the first conflict: Pegeen has been left alone to mind the alehouse at night. She would like company and protection. Shawn's character is quickly established when he is unwilling to protect her from the darkness for fear of upsetting Father Reilly. However, even Michael James is perturbed by the dark, as he doubles back before arriving at the wake because of it. All the characters realize that in darkness lies a litany of threats, including: ghosts, drunken farmhands and violent militiamen. The real threat, however, lies just outside in a ditch: Christy Mahon.
Offering shelter to this stranger invites a different and more profound darkness: the darkness of the human capacity for violent, subconscious desire. Part of what incensed contemporary audiences about Synge's play is that the play reveled in this dark behavior, but we may understand the villagers' celebration of Christy's patricide as an expression of their own subconscious desire to relish in their dark impulses and thereby upset the reigning moral order. Christy’s tale offers them a chance to imagine their own violent liberation from the stifling village life. But when Christy’s father appears, providing Christy a chance to kill him once and for all, the crowd turns on him. Darkness is easier to imagine than to confront directly, and so the village ultimately choose to keep their violent desires locked away, in the figurative dark. Overall, Synge uses his wild comedy to ask questions about what humans do in confronting their dark desires.
Religion
Religion in The Playboy serves as the reigning moral order of village life. However, Synge's depiction of it is quite nuanced, since characters frequently subvert religious expectation for the sake of self-interest. Shawn Keogh prefers to leave Pegeen alone in the dead of night with a madman abroad than risk censure for spending unchaperoned time with her. Meanwhile, these 'religious' villagers immediately celebrate Christy for his horrific patricide. The worse Christy's tale becomes, the more do the villagers grow enamored of him. What is implied through Pegeen's tale in particular is that freedom from religious restraint allows for freedom from the stifling nature of village life. Christy's crime allows her to imagine a life of self-realization, away from religious restraint. Though Synge never makes an explicit attack on religion in the play, it is posed as something antithetical to human freedom and individuality, and this conflict forms the center of the story.
Fathers
The theme of fathers is reflected everywhere in [The Playboy]. In general, fathers are presented in terms of authority. They demand obedience, which then poses a challenge to their children: do they obey, or revolt? There are three “fathers” within the play: Michael James (Pegeen’s father), Old Mahon (Christy’s father) and Father Reilly, the village priest. Each of these men is defined by the obedience he demands of his children (whether literal or figurative).
The most uncomplicated relationship is that between Father Reilly and Shawn Keogh. Father Reilly never appears in the play, but Shawn refers to him incessantly. Shawn, an orphan, frets over Father Reilly’s approval, and commits no action that might be censured. Shawn grants total obedience to Father Reilly, so much so that his obedience swallows his identity. It absolves him of having to make any difficult decision.
Headstrong Pegeen mostly obeys her father Michael James, but she never fails to argue her own point of view where it differs from his. Her most stunning act of disobedience is to insist upon marrying Christy instead of Shawn. Interestingly, her father's initial anger is overcome by her strength, until he eventually blesses the union. Of course, this blessing only lasts so long before Pegeen again makes herself subservient to him. By the end of the play, we see that Pegeen remains Michael's property, reliant on the life he provides, even despite her fiery personality. She is not willing to entirely repudiate him and run away.
Of course, it is relationship between Christy and Old Mahon that takes center stage. Though initially like Shawn in his life, obeying his father without a hint of rebellion, Christy eventually comes to distinguish himself as a revolutionary against his father's authority. He murders the man once by accident and again on purpose, so that even when Old Mahon survives, Christy demands the power. By the end, Christy has gained the authority, because he was willing to entirely repudiate his father. The sense is that we must be willing to destroy authority if we are to subvert it, something Pegeen has a sense of but is unable to entirely do.
Poetry
In many ways, what distinguishes Christy as a hero is less his actions and more his ability to represent those actions through language. Throughout the play, Pegeen and company are struck by Christy's verbal brilliance. In her first exchange with him, Pegeeen compares him to the great poets. Despite his limited education, Christy discovers a rhetorical skill as he articulates the subconscious desire to subvert authority, one that all of the villagers secretly share. As his own self-image strengthens, so does his language grow richer. It is telling that the prizes he wins in the sports competition symbolize a traditional Irish bard. Christy turns word into flesh, and language becomes one of the most important actors in the play. The sense is that we define ourselves not only by what we do, but also by how represent ourselves to others.
The Playboy
The concept of "The Playboy" is undoubtedly central to the play, considering its prominent place in the title. What is intriguing is that the concept shifts throughout the story. The Playboy is initially understood as a flirtatious man who attracts women. This aptitude is largely based on his mastery of language. Therefore, a playboy is one who can 'play' with words. And yet Christy drives this concept into a greater place, as his language and storytelling inflate his self-image. His identity grows to match the hyperbole of his language. As a result, he becomes a sports champion, suggesting that the Playboy is also an athletic specimen. By the end of the play, when Pegeen laments losing the "playboy," we understand that she does not regret losing a libertine, but rather a master of self-identity. The Playboy has come to represent not just a master of language or athletics, but in fact a master of himself and his own identity.
Marriage
Marriage is obviously central to a world centered around Church expectations, as the Irish countryside of his play is. However, it is also represented as a contentious, potentially violent, subject matter. Throughout the play, 'fathers' force marriage upon their 'children,' inspiring intense acts of rebellion or submission. Because marriage does not represent love, but rather economic convenience, characters must decide whether to submit to expectation or declare their identity in the face of these expectations.
The catalyst to Christy’s initial attack on his father was the latter's attempt to marry him to someone he did not like. Father Reilly controls Shawn’s fate through deciding whether to grant the dispensation. Most of all, the relationship between Christy and Pegeen reflects the way marriage stands in contrast to personal identity. Pegeen declares her own strength when she insists upon marrying Christy despite her father's intentions, and then later repudiates him of her own will. Similarly, Christy finally discovers his true potential when he repudiates Pegeen in turn, announcing his decision to "romp" forward, using woman as he pleases. Whether Pegeen will eventually submit to marrying Shawn is uncertain, but what is certain is that she has glimpsed that true freedom is stifled by social expectations like marriage.
Social Expectations
Christy’s murder of his father incites the action of The Playboy. This murder is both literal and metaphorical - in terms of the former, Christy does actually (try to) kill his father; in terms of the latter, he is celebrated not for striking an old man, but for representing an act of rebellion against social expectation in general.
There is an interesting interplay between the concepts of patricide — the literal killing of one’s father — and parricide —the murder of a family member. It seems that literal patricide shades into a more general category of parricide, since the murder has a greater metaphorical significance. In addition to striking his literal father, Christy strikes his 'family,' meaning the many aspects of society that attempt to define and limit people. What Christy 'kills' has great weight for the villagers because it represents a greater murder: of Church, law, village, country, of general subservience to social expectation. Christy's attempt at patricide enables him to represent a great liberator to the villagers. That they are shocked by his literal attack in the final act reveals that the villagers have turned his act into a symbol of defiance, one that allowed them to imagine destroying much greater concepts than an actual flesh-and-blood man.