Holden Caulfield experiences a collision with the adult world that he finds existentially absurd. The insincerity, the superficiality, the hypocrisy, the falseness, the cruelty, and the charades of adults repulse and disappoint Holden, leaving him disillusioned.
Holden feels alienated from all the "phonies" that he encounters. For instance, he finds repugnant the difference between the manner in which teachers act in a classroom and how they conduct themselves in other settings. His observations lead Holden to believe that only children, in their innocence of the world, are genuine.
In this disillusionment with the adult world, Holden wishes that he could protect children from this world of phoniness by "catching" innocent children before they fall victim to the world's falseness. He admires in children their candor, spontaneity, and kindness.
When he sneaks into his home to visit his sister Phoebe, Holden seeks refuge from the hypocrisy of people like his roommate, Stradlater; Ackley, who fabricates his sexual exploits; and his teacher Mr. Spencer, who displayed his sycophancy when Headmaster Thurmer entered his classroom:
Old Spencer'd practically kill himself chuckling and smiling and all, like as if Thurmer was a goddam prince or something.
He feels that Phoebe represents the goodness and honesty of children. But, after listening to his criticisms, she scolds her brother, telling him that he does not like anything that happens. He counters that he likes Allie and he likes sitting with Phoebe and talking. Phoebe reminds Holden that Allie is dead, suggesting that her brother cannot deal with the present. Certainly, Holden longs for the innocence and sensibleness that he believes existed in the past and in his childhood. For this reason, he wants to be a "catcher in the rye," grabbing children before they fall over the cliff of adolescence into the hypocritical world of adults.
In The Catcher in the Rye, Holden believes that the adult world is full of "phonies" and that people do not look out for the best interests of others whereas children are innocent. At the beginning of the novel, Holden says that his older brother D. B. is a great writer and that he used to love to listen to D. B.'s stories. Holden implies that the stories that D. B. wrote were artistic and genuine. However, D. B. moved to Hollywood to write scripts for films, and after he did that, Holden labeled him a "prostitute" meaning that he believes D. B. sold his talent to be used by the media simply to make money. Now he thinks that D. B. is just a phony. So, Holden looks to his other sibling, his younger sister Phoebe, as a symbol of the innocence of childhood. He wants to be there to protect Phoebe from the ills of the adult world. So, Holden's relationships with his two siblings reveal his thoughts about adults and kids.