I have started working through Pope Benedict's recent encyclical Caritas In Veritate (Love in Truth). He starts the letter with an introduction that meditates on the necessity of Charity and Truth in combination. One good quote:
A Christianity of charity without truth would be more or less interchangeable with a pool of good sentiments, helpful for social cohesion, but of little relevance.
This could be a mantra for Christian economists.
One of the themes of this introduction is to enlarge Christians' sphere of charity. Benedict states the problem as follows:
The risk for our time is that the de facto interdependence of people and nations is not matched by ethical interaction of consciences and minds that would give rise to truly human development.
Thus the problem is one of international social justice. He builds his case for social justice on the notion of "the common good:"
To take a stand for the common good is on the one hand to be solicitous for, and on the other hand to avail oneself of, that complex of institutions that give structure to the life of society, juridically, civilly, politically and culturally, making it the pólis, or "city". The more we strive to secure a common good corresponding to the real needs of our neighbours, the more effectively we love them.
And this common good is rooted in his definition of Charity:
It [charity] gives real substance to the personal relationship with God and with neighbour; it is the principle not only of micro-relationships (with friends, with family members or within small groups) but also of macro-relationships (social, economic and political ones).
The point here is that he will not allow an escape into personal-but-not-social virtue. We cannot settle for individual justice and not also justice in institutions:
This is the institutional path — we might also call it the political path — of charity, no less excellent and effective than the kind of charity which encounters the neighbour directly, outside the institutional mediation of the pólis.
So far so good. But to what degree are we justified in using the coercive force of the state as a means to be charitable and love our neighbor? He explicitly endorses the "political path" of charity, but does not justify the using the means of the state to make the overall system more just even when individuals are not willing to do so on their own. This is where things get messy. Perhaps this will come in the next section, perhaps someone will provide said justification in the comments section.