Chief Bromden is a self-declared unreliable narrator. In Part One, he presents himself, paradoxically, as a narrator who might get facts wrong but not the broader truth:
I been silent so long now it’s gonna roar out of me like floodwaters and you think the guy telling this is ranting and raving my God; you think this is too horrible to have really happened, this is too awful to be the truth! But, please. It’s still hard for me to have a clear mind thinking on it. But it’s the truth even if it didn’t happen.
Readers may stumble over this last line when they first read it. How can something be the truth "even if it didn't happen?" However, Bromden means what he says. This passage emphasizes his status not only as a storyteller but also as a storyteller who is himself a character in the story. He lived on the mental ward and pretended to be unable to hear or speak for 10 years. He kept everything he saw, heard, and felt bottled up inside, and he is now ready to let it out. Naturally, what comes out will be subjective, not objective, because he was on the ground in the hospital. He pleads with readers to take it as true anyway because it is true to him.
Kesey's novel aimed to shed light on the conditions endured by patients in American mental hospitals in the mid-20th century. Prevailing ideas about these hospitals had less to do with the dignity of the patients and more to do with the inconvenience mentally ill people posed to society. Institutions purported to "treat" mental illness, but they largely tried to instill obedience and compliance rather than addressing any underlying conditions that made it difficult for patients to get along socially. Kesey saw mental health institutions as enforcers of the status quo. For example, the hospital has no interest in helping Harding with the homophobia that has made him hate himself. By emphasizing Bromden's subjective experience as truth, Kesey elevated patients' stories, offered them a sense of dignity, and exposed some of the trauma they endured in these deeply flawed institutions. Just because someone is unable to recall events exactly as they happened, the novel suggests, does not mean that their story isn't real and worth telling.
In Part One, Bromden introduces Nurse Ratched not as a human, but as a machine "big as a tractor" who can disguise herself as a human. When the other patients come out of their dorms, there is an interesting interplay between dramatic irony and Bromden's status as an unreliable narrator:
[S]he has to change back before she’s caught in the shape of her hideous real self. By the time the patients get their eyes rubbed to where they can halfway see what the racket’s about, all they see is the head nurse, smiling and calm and cold as usual [...]
Bromden insists that there is dramatic irony at play: none of the other patients know what he knows about Nurse Ratched. He can see her "hideous real self" as a giant machine because she never notices that he is there to witness her take this shape. As soon as other patients are around, Nurse Ratched once again shape-shifts into the "smiling and calm and cold" nurse they all see her as.
Bromden understands that he hallucinates and that not everything he remembers from the mental hospital really happened. This is one moment where the reader can easily see that Bromden is caught in a delusion. This book is not a work of fantasy or science fiction, and the real world does not allow for humans and machines to transform into one another in the way Bromden describes. Nevertheless, he insists that he is being truthful in his account. Searching for the grain of truth in this scene, it becomes clear that he really does see something about the nurse that others fail to see. He understands the nurse as one piece in the Combine, the giant social machine that preys on people like him and the other patients. The nurse may not physically shape-shift, but Bromden identifies her as one of the moving parts in a huge system built on human suffering. This means that while she is one of the primary villains in all the men's stories, the real cause of their suffering is much larger than her. Were she to be removed from her position, she could easily be replaced. Rising up against what she represents will require completely dismantling the social systems that have failed the men on the ward.