McMurphy is in actuality a person with anti-social issues. However, he is up against a great foe in Nurse Ratchet who controls the ward and many aspects of the hospital. Initially, McMurphy does things to break down her personality and resist her attempts to dominate him. He gets the other patients involved in speaking out against her.
No one had dared to stand up to Nurse Ratchet before. When they see how brave and strong McMurphy is, they begin to speak out. McMurphy has Cheswick finally ready to complain at one of the meetings with Nurse Ratchet. What Cheswick does not know is that McMurphy just learned that Nurse Ratchet has the power to determine when he will be released, controls shock therapy treatments, and can even send patients for lobotomies. When Cheswick takes a stand against Ratchet, McMurphy does not support him. Later, Cheswick kills himself by getting his hand wedged in the pool grate.
The surprising thing that begins to change McMurphy into his idea as the advocate for the patient's is when he learns that many of them are there voluntarily. He is shocked that the prison like hospital would be how they would choose to spend their lives. It is at this point that he begins to believe that he has to take on the cause of helping them to gain their individuality.
Cheswick's death has been the catalyst that had demonstrated to McMurphy that his actions were not just a game. He takes his role more seriously. However, the irony is that he is trying to advocate for a group of people who had functioned well under the strict structure of the hospital and they could have left had they chosen to do so. Therefore, McMurphy is advocating for change for people who are frightened of change. In addition, McMurphy's methods for advocating the change become more violent such as his breaking glass to get his cigarettes.