In  a mixed  equilibrium,  some  players  pursue  the  strategy  of
ooperation,  and others pursue the strategy of  appropriation.  In an
volutionary  equilibrium,  all  strategies  that  persist yield  the  same
bjective payoff.  When  all  strategies  yield  the  same  payoff, some
eople  conform to the norm adventitiously.  Equilibrium is reached
y adjusting  the number  of people who  conform  adventitiously  to
he norm.  Consequently,  the presence of people who conform from
rinciple  does  not affect  the  equilibrium.
For example,  assume the rate of  return for players in  the agency
game  equalizes  when  eighty players  cooperate  and  twenty  players
appropriate.  Furthermore,  assume that sixty players cooperate from
principle  and  that  twenty  players  cooperate  adventitiously.  Now
assume  that one of  the appropriators  is convinced  to change his evil
ways and start cooperating.  The change in his behavior causes a dis-
equilibrium  in which  eighty-one  players  cooperate  and  nineteen
players  appropriate.  Equilibrium  will  be  restored  by  one  of  the
adventitious cooperators  changing his strategy  from cooperation  to
appropriation.  Thus,  the internalization  of the norm by one more
player  changes  the  identity  of  the  cooperators,  but  not  their
number.
Marginal  players  change  their behavior when  objective payoffs
change  by a  small  amount, whereas  inframarginal  players  persist in
their  current  behavior.  The  argument  in  this  Section  can  be
summarized by stating that adventitious conformity is marginal and
principled conformity is inframarginal  in a mixed evolutionary equi-
librium.  A change  in  the number of inframarginal players  does not
change  the  equilibrium, which  is  determined by marginal  players.

以上三个颜色三段文字是一个文献中的论述，我不是学经济学的，但是这段文献对我来说很重要，求高手解释。200金币相赠。