The argument can be found in chapter 17 of the novel, when Mond is explaining the society's philosophy to John the savage. This chapter can be a thirst-quenching chapter because it breaks down the rationale behind the cloning, the soma, the promiscuity, the feelies, and the class system under which they live. John asks about all of the things that the society lives without, such as God, religion, heroism, sacrifice, and responsibility to others in a community. Ultimately, Mond justifies his point according to the one thing that every civilization strives for--happiness:
"You must make your choice. Our civilization has chosen machinery and medicine and happiness. That's why I have to keep these books locked up in the safe" (281).
Happiness comes down to a person choosing how s/he wants to live and being able to live that way. Even though people in Mond's world are manipulated genetically and mentally to accept their position in the society, they are arguably happy as they are and don't need John to bring in Shakespeare or religion to make anything "better".