On the Significance of the Common Good

It seems to me that people who profess to believe in capitalism who are quick to dismiss the importance of the common good do so at their own expense. If we define the common good as wealth per capita, then it appears to me that while the ultimate moral justification for a social system may not be the fact that it maximizes the common good, maximizing the common good is nevertheless a function of an ideal social system. It would be troubling, wouldn't it, if one declared a social system as moral, only to watch it plunge an adopting society into agony and pauperism. The maximization of the common good should be understood as a necessary concomitant of an ideal social system; it is an indicator that the ideal social system has perhaps been achieved.