A Little Life by Hanya Yanagihara. This is true for a world where casual violence is available via the internet and at the same time more remote as few people have contact with the dying. "When we say that a work of fiction is infected with gratuitous brutality, what are we really saying?" asks Yanagihara, the daughter of a doctor who treats the terminally ill. "All brutality is gratuitous. There is no reason for it. But it is part of being human, and therefore it is the stuff of literature. For literature to ignore this, to try to conceal or avoid it, is an act of nothing less than artistic irresponsibility, a covering of the eyes and a silencing of the tongue because of some specious idea that there are certain territories into which fiction is not supposed to wander. "But it is not only the fiction writer's right, but the fiction writer's duty, to not just wander, but to march into those territories, to look at the putrefying ugliness of what humans can be – and then to report back. It is the least she can do.

"Not because her art permits her to – but because her own humanity compels her to. Can't art – and shouldn't art – encourage us to imagine the human condition, even at, especially at, its cruellest and smallest?" A Little Life revolves around four classmates from a Massachusetts college who come to flat in New York: aspiring actor Willem, painter JB, architect Malcolm and Jude, a brilliant lawyer haunted by the trauma of his dysfunctional childhood. As they reach midlife, the three struggle to help Jude overcome the unspeakable experiences which define his existence. The strength of the male friendships give the book its heart and occasional moments of elation but Yanagihara strongly argues – from a position of story authenticity – that there is some trauma that can never be healed. "It was always going to be about someone who wasn't going to get better," Yanagihara, 41, told Fairfax Media. "What does the story then become about if it becomes a story of hope and that hope is never quite answered? "I think hope can be tyrannical for many people, this idea, whether it is visited on them by society or they are taught to believe it about themselves, that if they hope hard enough or they work hard enough that they might be able to effect some sort of major or elemental change in their life, and I think for many people this is simply not the case.

"For many people the central struggle of life is the pole between your hope and the acceptance or resignation towards what you know is going to happen." Refusing to read reviews or join Twitter or Facebook, Yanagihara is surprised as much as anyone that A Little Life has taken off. Its shortlisting for the Man Booker Prize only partly explains its success. "Its growth has been organic and old-fashioned," says Yanagihara. "It went from bookseller to reader and then from reader to reader. In an age in which literary books sell fewer and fewer copies it's been thrilling." A Little Life was written over 18 months, compared to the 18 years it took Yanagihara to write her first novel, The People in the Trees. She wrote deliberately, and though saddened by where she took Jude, seemed never as emotionally invested in his fate as those readers who have cried buckets. The duty of a writer to their reader, as Yanagihara will tell her closing night audience, is not to provide a happy ending but "full authorial engagement with the thing she is creating". "That's it. I don't think a reader wants to be babied, I don't think a reader wants to be coddled, I don't think a reader wants to be patronised." Linda Morris is on Facebook and Twitter @LindaMorrissmh