Damis, angry, rages to Dorine about the "the conceited fool" Tartuffe, but she calms him by suggesting a plan. She has set up a meeting between Elmire and Tartuffe, so that Elmire can intercede on her step-daughter's behalf. Since Tartuffe fancies Elmire, she has the best chance of tricking him into refusing Orgon's offer of marriage. Despite Dorine's insistence that his temper could get them in trouble, Damis insists on hiding to eavesdrop on the encounter between Tartuffe and Elmire.
Tartuffe and his servant Laurent begin to enter, but when Tartuffe sees Dorine there, he makes a show of piety by asking Laurent to fetch his hair shirt and scourge. Before leaving, Dorine tells him that Elmire wishes to see him.
Elmire enters, and Tartuffe inquires after her health. When he feverishly insists he would trade his own health for hers, Elmire admits she finds his zeal over her "disconcerting." Tartuffe counters that he relishes the chance to be alone with her so he can show her his "entire soul." He then sits next to her and places his hand on her knee. Shocked, she asks his design, and he pretends he admires the lace of her dress.
She changes the subject to inquire about the proposed marriage. Tartuffe confirms the rumor, but insinuates he would find better reward in her. He finally admits his intense feelings for her, which surprises Elmire since his admission contradicts his claims of piety. Tartuffe insists his piety is only compromised in her presence, when he is overcome by her beauty and charm. He begs for her love, and promises to keep the affair secret. She rejects the offer, and suggests her husband would surely revolt to learn about his advance. Tartuffe, however, suggests he would be found innocent considering the allure her "perfect face." Though she definitively rejects his offer, she promises to keep his lecherous secret if he refuses Mariane, and supports the union between her and Valere.
Angry, Damis suddenly emerges from his hiding place and confronts Tartuffe, threatening to reveal his hypocrisy to Orgon. Elmire tries to soften her step-son's anger by suggesting she has remedied the issue, but he rages, "This fanatic in his insolent pride, / Brought chaos to my house, and would divide / Me and my father – unforgivable!" Nothing Elmire says can dissuade him from his intent.
Orgon enters, and Damis tells his father about Tartuffe's lechery. Elmire is upset that the situation has now escalated. Tartuffe immediately feigns humility, insisting that he should be punished despite his innocence, since he is surely guilty of other sins. Moved by Tartuffe's selflessness, Orgon lashes out at Damis for speaking falsely. The more heinously Tartuffe berates himself, the angrier Orgon grows at Damis. When Damis refuses to admit dishonesty, Orgon banishes and disinherits him.
Orgon then apologizes to Tartuffe, who swoons in his fake piety and insists he should leave since he has caused such discord amongst the family. Orgon convinces him to stay, but Tartuffe insists he should never see Elmire again, as a "hefty penance." Orgon disagrees, and insists Tartuffe should in fact spend all his time around her to flaunt his innocence in the matter. Further, he promises to name Tartuffe as his heir because he has been "a good and faithful friend."
It is not until Act III that the titular character enters, with the hilarious line, "Laurent, lock up my scourge and hair / shirt, too" (31). The line both confirms and expands the audience's expectations. A hair shirt was a unwashed garment of coarse cloth that was worn by medieval monks as a sign of great piety. Naturally, the audience knows that Tartuffe is a scoundrel and hypocrite by this point, and yet would be amused by the extent of his deception upon seeing someone already on stage. Moliere himself described the effect of the entrance as such: "I have employed … two entire acts to prepare for the entrance of my scoundrel. He does not fool the audience for a single moment; one knows from the first the marks I have given him; and from one end to the other he says not a word and performs not an action which does not paint for the spectator the character of an evil man." In other words, most of Tartuffe's time onstage works through dramatic irony - we know that he speaks falsely, which means the actor can play his ridiculous piety truthfully. The more an actor plays the piety truthfully, the funnier the disconnect is.
The main exception to the use of dramatic irony comes in Tartuffe's attempts to seduce Elmire, a shocking and fascinating scene because of its unfettered lecherousness. The contrast between his disguise of holiness and his immediate lust is amusing, all the more so because the language he uses continues to suggest his penchant for deception. He does not outwardly admit that his holiness is a lie, but rather rationalizes ways in which it allows him to pursue this affair. For instance, he suggests that her beauty is greater than piety, which allows him to continue his ruse while still attempting to fulfill his inappropriate lust.
Indeed, it is lust that ultimately destroys Tartuffe. The critic Harold C. Knutson considered the attempted seduction in terms of the stock character of the prude, which was often used in comedies of the time. He writes: "The prude in comedy, then, is by definition a figure of ridicule. In her hypocritical refusal of the flesh and her frenzied if repressed libido, she embodies the contradictory extremes that the ardent but decorous suitors of comedy are meant to mediate. In no other character is this feature so apparent as in Moliere's only male prude, Tartuffe." Tartuffe's careful attempts to appear prudish and libido-less "foreshadow the whole unveiling of Tartuffe's character, his explicit and unbridled sexuality (more appropriate to masculine decorum but still totally at odds with respectful courtship)—and the studied way in which he preaches virtue." In other words, Tartuffe is destroyed less by his sexuality than by his refusal to openly admit that sexual nature. Because he tries to pretend he is otherwise, he sets the stage that will eventually collapse around him.
Damis reveals the limitations of unbridled passion in this scene as well. Elmire, through measured diplomacy, has engineered their victory for Mariane. However, Damis has no political instinct rushes out to tell Orgon, believing that the extent of his passion will be proof in itself. The audience should know that Orgon's blindness will prohibit him from believing hearsay, but Damis cannot imagine it. Again, we see a possibility that Orgon's embrace of Tartuffe is his veiled response to disappointment over his own family's characteristics. He is so much enamored of Tartuffe that his own son's passion leads him to bequeath his fortune and home to the man.
Overall, the play's comedy reaches a new level in this Act, largely because Tartuffe arrives. His pompous entrance, added to his lustful attempt to seduce Elmire and his exaggerated asceticism after Damis's accusations, allow for a marvelously rich stage character. It is precisely because his behavior is so repugnant but ridiculous that we can laugh rather than empathize. Further, his language - which as discussed above, always maintains a sense of decorum even when he proposes entirely disgusting things - is magnificently constructed so that there are always layers for an actor to explore.
The scene after Damis's accusations are particularly masterful in the use of dramatic irony. Tartuffe nearly confesses his guilt, saying, "I'm wicked through and through...And I see that Heaven, to punish me, / Has mortified my soul quite publicly. / What punishment I get, however great, / I well deserve so I'll accept my fate." Tartuffe's feigned humility stands in contrast to Damis's boiling anger. Orgon grows more convinced in Tartuffe's innocence even as the audience is more shocked by his impertinence. After all, he has just admitted his guilt, but Orgon reinterprets the language to match his own preconceived notion. We groan with disappointment and delight when the gullible Orgon exiles his own son, tells Tartuffe to see Elmire as much as possible, and confirms Tartuffe as his future son-in-law and heir. Perhaps the most effective way that Moliere communicates his ideas about the distinction between appearance and reality is through this lovely, hysterical dramatic irony.