In the early part of the story, McMurphy played the system, refusing to get with the program and generally making a complete nuisance of himself. But once he realized that Nurse Ratched has the power to decide as and when he can be released from the institution, Randle started conforming to the rules, much to the disappointment of some of the other patients.

In defying Nurse Ratched for as long as he did, McMurphy effectively let the genie out of the bottle. Once he'd undermined her authority, there was to be no turning back, either for him or for the other men in the institution. For the first time, McMurphy's fellow inmates had been a given an all-too-brief taste of freedom. But now that McMurphy's on his best behavior, whatever freedom they enjoyed has been suddenly snatched away from them.

Lacking the mental strength and maturity to handle such a sudden reversal, Cheswick commits suicide. In turn, this causes McMurphy to reflect on how the other men have come to see him as some kind of hero, a charismatic leader who provides an alternative authority figure to Nurse Ratched. Probably for the first time in his life, McMurphy feels a sense of responsibility toward others. That means standing with the other men and fighting back against the system.

In Part II of this novel we see a change in McMurphy's attitude which comes when he realises that Nurse Ratched is the one who has control over when he is released or not and what kind of treatment he receives. He suddenly turns into a model patient and all of the other patients are extremely disappointed with this. However, what happens to Cheswick helps McMurphy to see that he has become complicit with the Combine, the forces within society that keep those who are branded "mentally ill" within the asylum, and that he needs to fight for the patients and himself again. Even though Chesick tells McMurphy he understands his reasons for not challenging Nurse Ratched any more, it is clear that Bromden suggests his suicide is a direct response of the loss of hope caused by McMurphy's conformity:

He told McMurphy this while we were all being taken over to the swimming pool. But just as soon as we got to the pool he said he did wish something mighta been done, though, and dove into the water. And got his fingers stuck some way in the grate...

It is strongly suggested that Cheswick killed himself because of the loss of hope that was the result of McMurphy choosing to conform to Nurse Ratched's rules and regulations. McMurphy realises through this experience the responsibility he has towards all of the patients, and this gives him the courage to begin opposing Nurse Ratched again, symbolised through his breaking of the glass to her office.