John stuart mill says that humans by nature desire happiness and nothing but happiness; therefore happiness is the standard by which we should judge human conduct, and therefore the principle of utility is the heart of morality. but this argument is controversial, because:

With regard to personality, it appears that: a) there is little consistency of behavior from one situation to the next and little consistency of traits over the life span. b) there is little consistency of behavior from one situation to the next but significant consistency of traits over the life span. c) there is significant consistency of behavior from one situation to the next but little consistency of traits over the life span. d) there is significant consistency of behavior from one situation to the next and significant consistency of traits over the life span.