After a brief delay, during which Berenger watches the rhinos out the window, Dudard opens the door for Daisy. Dudard insinuates that Daisy is coming for a romantic rendezvous, but she insists she is just a "good friend." While offering sympathy to Berenger, Daisy also appears not to care too deeply about the epidemic. She informs them that Botard has metamorphosed. Berenger can't believe it, feeling that Botard was fooling them in a disguise. Daisy says Botard's last words were "We must move with the times!" On reflection, Berenger justifies Botard's behavior, indicting his stubbornness as only a pose. Dudard believes Botard was following Papillon, his superior, and both men agree that the rhinoceroses are anarchic, because they are in the minority—"for the moment."
All three discuss the social problems caused by the rhinos—especially the problem of eliminating them. Daisy and Dudard say that acclimating oneself to the rhinos is the best solution, but Berenger resists. They start to have lunch, but are interrupted by a crumbling wall outside. The dust settles and they see that the fire station has been sacked, and that the firemen have turned into rhinos and now march in a regiment, led by drums. Berenger's will seems shaken by the accelerating epidemic. Dudard makes excuses to leave under the guise of politeness. He then reveals that he wants to experience the epidemic first-hand and join the "universal family." Berenger tries to stop him, but Daisy believes in letting him, and people in general, make their own decisions. Dudard soon turns into a rhino outside.
According to the stage directions, the thunderous, thickening stampede (in the form of stylized heads appearing on the wall) creates a "musical sound" and the heads "seem to become more and more beautiful." Berenger makes passionate declarations of love to the nonchalant Daisy. Berenger laments Dudard's demise, and Daisy reminds Berenger that they have no right to interfere in other's lives. As Berenger points out, though, Daisy has assumed control of their own relationship. She explains the difference: as she loves Berenger (and not Dudard), she has the right to interfere in his life. Berenger seizes upon Daisy's admittance of her love for him, pointing out that Dudard would have only been an "obstacle" between them.
Daisy pours some brandy for Berenger, rewarding him for being a "good boy." She removes his bandage—still no signs of a transformation—and they fantasize about their lives together. Berenger claims he will defend her, but Daisy says no one intends them any harm. He replies that we sometimes do harm by simply not preventing harm. He blames himself and Daisy for contributing, through lack of sympathy, to the transformations of Jean and Papillon, respectively. Daisy convinces him to shrug off the guilt; as relatively "good" people, they have a right to happy lives despite the circumstances around them. Berenger agrees, and surmises that guilt is what probably turned a lot of people into rhinos in the first place.
The phone rings, and Daisy cautions Berenger not to pick it up. Berenger answers it, thinking it will be the authorities, but hears only rhino trumpeting from the phone. Daisy hangs it up, frightened. Berenger claims he was expecting the prank rhino-call, and Daisy states that you can only predict things once they've happened. The phone rings again, and they turn to the radio for help, but the rhinos have taken that over, as well. They grow more terrified, aware that they are the last hold-outs.
Upstairs, a rhino stampede sparks eruptions within the house. Now Berenger wants to live a guiltless existence, and offers some brandy to the sunken Daisy, who believes the responsibility for the transformation lies with them. She believes they must adapt to their new neighbors, but Berenger proposes they regenerate the human race, like Adam and Eve. Daisy has given up hope, calling themselves the abnormal ones; she finds the power of the rhinos seductive, and human love a "weakness." In a series of quick reversals, Berenger slaps her, she recoils and weeps, he apologizes and declares that he'll never surrender and that he'll help her to the end, and she pledges her loyalty to him. The noise of the rhinos becomes more melodious. Berenger calls the sound roaring, while Daisy believes it is singing. He calls her stupid, and Daisy breaks up with him and leaves.
Berenger examines himself in the mirror, at first unaware that Daisy has left. He still finds the human form attractive. He realizes Daisy has left and calls out to her down the stairwell, but soon gives up. Resentful that Daisy has left, he turns his anger to the rhinos, barricades his room and plugs his ears. He vows that they'll never "get" him. He feels guilty for driving Daisy out, as she will surely turn into a rhino. He wonders if it would even be possible to convert the rhinos back to humans, as he doesn't know their language. He then considers that his own language is just as alien to them, and the concept of language soon becomes alien to him—what words are he using, what constitutes language? He wonders what he looks like, and inspects some photographs. He cannot recognize any of his former friends—but he does identify himself and hangs a few of his pictures on the wall beside the rhino heads. They turn out to be pictures of unattractive people and, compared to the elegant rhino heads, are even more grotesque. He envies the rhinos their horns, their rough, green skin, their melodious trumpet call. He tries to emulate them but he cannot. At the brink of desperation, he decides that as the last figure of humanity, he will fight the rhinos. The play ends on his line "I'm not capitulating!"
Berenger's and Daisy's dual desires to fight the rhinos and to surrender vacillate wildly in the first part of this action-packed section. He is inactive at the start, not hearing Daisy's knock at the door. This is the third delay in opening the door for someone else in the play (Jean for Berenger in Act Two, part two; Berenger for Dudard in the first part of Act Three), and each occasion seems to indicate a physical disconnection from humanity, which the occupant of the house is in no hurry to remedy. While Berenger is at first resistant to Dudard's and Daisy's idea of acclimating himself to the rhinos and to not worrying over it, he later lets Daisy coax him into believing that he should lead a guiltless life, and goes a step further in blaming guilt (and other emotions that show a lack of "purity," as Daisy says) as a cause of the metamorphoses. Daisy's reversals turn to an even more staccato rhythm; she alternates her devotion to Berenger and to the rhinos so quickly, the effect would be comic were the outcome not so grave.
Guilt and love are the dominant emotions in the finale, and Daisy's and Berenger's ideas of these emotions clash in profound ways. The "happy," guiltless life Daisy seeks detaches itself from humanity. The love she expresses for Berenger, then, is simply a love for another individual, not for all humanity; as Berenger expresses, "Happiness is such an egotistical thing!" Berenger is at first manipulated by Daisy into accepting this guiltless life. He greedily misinterprets her distinction between her interference in Dudard's life and his own, not comprehending Daisy's belief that love allows you to act on behalf of someone else. However, Berenger renews his guilt, later choosing to absorb the guilt for Daisy's own departure, even though she probably would have done it anyway. That he still feels concerned for someone who just abandoned him in the worst way shows that Berenger holds unconditional love not only for Daisy, but also for humanity. To love one human, Ionesco implies, is not enough for a life of significance; one must love and be willing to take responsibility for all humanity, and this allows Berenger to interfere on behalf of the world.
The metaphor of fascism blooms overtly at the end. The firemen have turned into an organized militia, showing that authority is just as susceptible to corruption as anyone else; Papillon's earlier transformation and the metamorphoses of the aristocracy and media drum the point home. Dudard's desire to belong to the "universal family" of rhinos suggests an underlying genetic component to the transformations, a movement to Aryan-style racial cleansing (as well as calling attention to the scarcity of family in Rhinoceros; none of the major characters seems to have any relatives whatsoever). Ionesco does not make his point in as one-sided a manner as a lesser dramatist might: the rhinos not only become more beautiful to Daisy, but to the audience as well. Their trumpeting is melodic to our ears, too, and we can understand why she would be seduced by the rhinos, especially when compared to the pictures of ugly humans alongside them. Yet Berenger's observation about the indirect nature of harm is Ionesco's final critique of John Stuart Mill's harm principle: "Sometimes one does harm without meaning to, or rather one allows it to go unchecked." Seemingly innocuous action can, in fact, be violent. Worse yet, remaining passive, without commitment or choices, can cause harm and makes the passive individual as culpable as the violent one.
The play ends with repetitions on the theme that the universe is absurd, and that logic cannot explain everything. Daisy makes the comment that one can predict things only after they have happened, but this is not even true. Berenger unsuccessfully attempts to justify Botard's absurd transformation (that it was a disguise, which copies Jean's earlier statement about Mr. Boeuf, and that it was a foreseeable collapse of Botard's false stubbornness, which echoes Dudard's earlier words). Both are, in fact, completely wrong; the true "disguise" is the human skin the savage characters were wearing all along, and Botard's stubbornness was not at all a pose. Botard may have held out initially because he was mulish, but once he was presented with proof of the rhinos in Act Two, his stubbornness did not relent, but switched sides to account for the rhinos. One can reasonably imagine that later on, when he realized he was one of the few humans left, Botard would have stubbornly insisted that being a rhino is right. Even those absurdities that can be somewhat rationalized—such as the metamorphoses as a result of collective consciousness—inspire new, unanswerable questions: Why rhinoceroses, for instance, and not bears, elephants, or other savage animals? Why do some of the rhinos have one horn, and some have two—is Ionesco suggesting there will later be division even among the rhinos? The racial distinction between Asiatic and African seems to suggest that there will be.
Oddly enough, the play, which emphasizes the absurdity and inapplicability of logic, accords perfectly to the logic of the Aristotelian three-act structure, with a character whose arc forms as great a transformation as those physical ones around him (an irony similar to the end of Franz Kafka's "The Metamorphosis," in which the daughter of the family is the one who has truly changed, not Gregor the insect). Some critics read ambiguity into the ending; perhaps Berenger's stand-off is yet another whimsical turn of his mind (his and Daisy's temporary inversion of character in this scene and other instances throughout reinforce this notion). However, everything leading up to Berenger's transformation suggests a slowly developing awareness of the need for a life of commitment. Berenger's name sounds like the French word "déranger," or "to disturb" (Berenger certainly is disturbed throughout the play, as is the logic of the universe; Ionesco uses a semi-autobiographical character named "Berenger" in several of his other plays). Backwards, his name is close to "régénérer," "to regenerate" (and his idea of restoring the human race with him and Daisy as Adam and Eve lends credence to this wordplay, as does his final decision to fight the dissolution of the human race). Whether or not one buys into these coincidences, it is clear Berenger eventually transforms from a disturbed individual into one who wants to regenerate humanity, and Ionesco closes the curtain with this decision because it appears final. The tidy wrap-up of Rhinoceros implies that perhaps only in art can absurdity be refined into logic.