Cleante confronts Tartuffe, demanding he help remedy the split between Orgon and Damis. Tartuffe counters that "Heaven's best interests will have been served," and that Damis was justly punished. When Cleante suggests that it contradicts his piety to assume responsibility for Earthly punishments that should be in God's hands, Tartuffe hurriedly exits, claiming he has "pious duties" to perform.
Orgon, Mariane, Elmire, Cleante, and Dorine talk together. Mariane begs her father to release her from her "vows of obedience," promising to relinquish the property she inherited from her mother if she can marry Valere. Orgon refuses all arguments that resist the match with Tartuffe. When Elmire insists upon Damis's accusations were true, Orgon counters that her cool demeanor at the time suggested otherwise. She explains that calmness is more effective than temper in addressing difficult situations, especially over behavior she expects from men.
To convince him of Tartuffe's wickedness, Elmire suggests Orgon hide and eavesdrop on a conversation between her and Tartuffe. He agrees, thinking he will call her bluff. Dorine warns Elmire to be carefully, because Tartuffe is tricky.
Orgon hides under a table as Elmire cautions him to excuse her sensual flirtation with Tartuffe, which she must employ to ensnare him. She tells him to stay hidden until he is firmly convinced of Tartuffe's wickedness.
When Tartuffe enters, Elmire praises Orgon's obliviousness, since it means she can return his affections without fear or reservation. Tartuffe is suspicious about her new passion, but she claims that she usually maintains a cool demeanor to protect her honor, even when she is inwardly excited. As evidence, she reminds him how she cautioned Damis to control his temper, and then suggests she opposed Tartuffe's match with Mariane solely so she could have the man to herself.
Tartuffe softens, but insists that he will need physical proof of her affection. Elmire becomes uncomfortable with where her ruse might lead, and begins coughing to alert Orgon that he can now reveal himself. When Orgon does not take the bait, she asks Tartuffe to show some patience, but he insists that they should enjoy one another immediately. Furthermore, he explains that he is one of secrecy's "best pupils / And practitioners," that "evil exists only when it's known."
Elmire awkwardly agrees to his demand, but first asks him to check outside the doorway to ensure Orgon is not nearby. Tartuffe agrees to the condition, and leaves.
Orgon immediately reveals himself, angry and insisting Tartuffe is "straight from Hell." When Tartuffe returns, he is startled to see Orgon, who insults him: "Some holy man you are, to wreck my life, /Marry my daughter? Lust after my wife?" He interrupts Tartuffe's attempted explanations, and banishes the man from his house. However, on his way out, Tartuffe reminds Orgon that he now holds the deed to Orgon's house, and promises to exert his control over the family as penance.
After he leaves, Elmire asks Orgon to explain. The patriarch laments that he gave Tartuffe both the deed to the house and a strongbox containing materials that could cause him trouble. He races off to try and find the box.
In Act IV, things begin to come undone. Orgon finally understands the depth of Tartuffe's deception, but his past errors threaten to cause great harm. Though there are many comic moments in the act - particularly in Elmire's faux-seduction of Tartuffe - the act ends on an ominous note, particularly in regards to the strongbox. It is difficult for a first-time reader or audience member to know what could be more problematic than the deed to the house, and that mystery serves as potent reminder of the penance we often pay for an inability to recognize hypocrisy.
The house, in fact, is a very interesting component to the story. Many critics believe that Moliere, unlike Shakespeare, spent too little effort developing a real sense of setting in his plays. Classical theatre was generally less interested in such concerns than romantic and naturalistic theatre later was, but Moliere is particularly criticized for under-emphasizing setting and props. The common understanding, instead, is that he preferred to emphasize dialogue, characters, scene structures, and comedy. However, the critic Quentin Hope ably refutes these assumptions, claiming that the bourgeois Paris house in Tartuffe "[has] a particular importance."
First of all, the house's symbolic value is established in the play's opening scene. Though it should be safe and nurturing, it has been penetrated by a noxious outsider. It has been contaminated; Tartuffe is like a parasite, feeding off of the inhabitants. Interestingly, this parasite has the most props of any character in the play, including a hair shirt, scourge, and pocket watch. The effect is to suggest he is a real fleshly body, which drinks, eats, sleeps, and lusts. This stands in contrast to the cleanliness and orderliness of the bourgeois Parisian house, which he interrupts and spoils. Consider the way Dorine convinces Mariane to oppose the match in Act II - she suggests life with Tartuffe would have a stultifying rural flavor, far removed from the luster and elegance of a Parisian life.
Yet Orgon embraces Tartuffe precisely because he hopes the latter will ensure this sense of cleanliness. As Hope writes, the house as Madame Pernelle understands it in the first scene is "a noisy, disputatious, outspoken household; a neighborhood buzzing with talk and gossip; a family accustomed to the pleasures offered by a sociable, lively capital city that finds itself invited against its will to abandon earthly pursuits and follow an intruder up the straight and narrow path to heaven."
Thus, the house has a dual symbolic purpose for Orgon: it is a symbol of the family's social standing, as well as a shelter to protect them. Understanding it this way, the entrances and exits into and from the house take on much more significance. Characters leave with curses (Madame Pernelle) or are thrown out (Damis), while others beguile their way in (Tartuffe, Monsieur Loyal). Orgon's return to the house in the first act is a "situation often used in drama: the return of the lord and master." His return inaugurates all of the troublous events of the play. Tartuffe's entrance is even more interesting, as he is already safely ensconced in the house when the play begins, and therefore does not need to appear onstage until the third act. The issue for him will be how to force him to exit.
Overall, the house becomes the prize, then, less for its physical attributes than for its social import. The conflict at the beginning is over who should control the house, and how that control will communicate the family's nature to those in society around it. The house is the symbol of the family's identity. As Hope explains, "When a bourgeois like Orgon loses his house, he loses his identity. The bourgeois in Moliere considers his house, his wife, and his children his property...a bourgeois stripped of his possessions descends to the level of a Tartuffe before his meeting with Orgon." The central conflict can be understood as being waged over who has control of this house, and subsequently, the family's identity.
Moliere, then, was not a "clumsy or careless writer who slapped his plays together with little care for anything except characters and ideas." The place and setting of Tartuffe reinforce the drama, tension, and underlying message of the play. Further, they suggest his underlying interest in class - even though this play does not have an explicit political message about class, those ideas do run through it.
Though the characters, save Orgon, do not exhibit much variation in this Act, there are great comic moments for actors to discover. Cleante's accusations at the top of the act merely reinforce our conceptions of their perspectives, but the faux-seduction employs much dramatic irony. The audience alone understands who knows what, and it is delightful and suspenseful to wonder how far Elmire will have to go with this man she detests.