1) Reading an article, “Social Charity: A new virtue for moral theology”, from the May 2008 issue of the magazine Homiletic and Pastoral Review—available by subscription from Ignatius Press—I came across this regarding solidarity, a foundational concept of Catholic Social Teaching:
“..solidarity also represents a moral relationship between man and his fellow man…Even if the downfall of one’s fellow man were to one’s advantage, one is not permitted to wish for this let alone help bring it about.”
“The essence of an awareness of this interdependence throughout society, up to and including the international level, constitutes solidarity as explained by Pope John Paul II in Part V of Sollicitudo Rei Socialis [On Social Concern] “When interdependence becomes recognized in this way, the correlative response as a moral and social attitude, as a "virtue," is solidarity.” (# 38)
2) The corresponding concept in the field of public administration is equity, and it is the administrative tool that Grover Starling (2005) notes asks the following questions in terms of the distribution of public resources:
“Are benefits distributed equitably with respect to region, income, sex, ethnicity, age, and so forth? To what degree do those using the service pay directly for its benefits?” (Managing the Public Sector, 7th Edition. p. 256)
While equity primarily concerns itself with the temporal, solidarity concerns itself with the eternal, and it is why it is important Catholics become more active in the public square.