Why does McMurphy reject Harding's plan for his escape from the institution? How does this begin to establish him as a tragic character?

For one McMurphy dislikes Harding. This is the guy that planned to set McMurphy up. Also we get a sense that McMurphy doesn't want to leave. This sets himself up as a tragic character. McMurphy is being assimilated, in his own way, into the combine that is this mental institution.