One Flew Over the Cuckoo's Nest Part 2

For this post I would like to talk about McMurphy's actions between the whole second part of the book. As a person reads about McMurphy's action they can see that he seemed to be the only hope for the other prisoner's of this correcting facility. At first he starts up every argument to make things more fair for the others who were forced by the state, or by their own humiliation into this prison. But as time goes own, and McMurphy learns more about the control the Big Nurse has over everyone he backs down bringing down everyone else with him. Any one that read the story knows this happens but I'm asking about McMurphy's reasons.

I really wonder what was going through his mind, and why did he step down only to step up again later. Did he realize that he would be there a long time, and decided he needed to make things better for everyone since no one else would do it? Did he just wanted to help every gain back a little respect? Or did he just want to fight the Big Nurse, all the nurses, the doctor, and the whole system? What were the motives behind McMurphy, and the motive that made the writer chose this part in his story. Although, I may never figure it out I will always wonder.