Mustapha Mond quite reasonably points out that he and his fellow World Controllers do not like inconvenience and discomfort. John perversely claims that he does. To comfort and convenience he opposes God, poetry, danger, freedom, goodness, and sin. It is at this point that Mond says John is claiming the right to be unhappy:
Not to mention the right to grow old and ugly and impotent; the right to have syphilis and cancer; the right to have too little to eat; the right to be lousy; the right to live in constant apprehension of what may happen to-morrow; the right to catch typhoid; the right to be tortured by unspeakable pains of every kind.
Mond mentions several specific types of pain that flesh is heir to. There is the universal humiliation of old age, gradually growing weaker and uglier. There is disease: syphilis, cancer, and typhoid. There is hunger and dirt. There is anxiety about the future. Finally, there is the experience of physical pain, as universal as old age. All these, Mond argues, are objectively bad things. The World Controllers have done a good thing in removing them from people's lives.
Mond's philosophical position is clear. He is a Utilitarian and a hedonist. He has, in fact, a great many philosophers on his side. Even Aristotle, in discussing virtue, regards it first as the means to achieve happiness. John's view, however, is also expressed by Aristotle in his discussions of tragedy. The Greek tragedies show their protagonists growing and learning through suffering. If we do not suffer, we do not develop, and we remain shallow and selfish. This is a strong riposte to Mond's Utilitarian hedonism, but does not necessarily defeat it. One might argue that all we do to alleviate unhappiness will never be enough. People will always find ways to make themselves and others unhappy; so one would have to be living a very privileged life indeed before a potential shortage of pain and angst struck one as a serious problem.