Mirror of Justice contributor Thomas Berg has an excellent post on what Catholic social teaching may have to say about growing economic inequality.
1. "Great disparity seems likely to make it harder for people to practicethe value of solidarity, that is, 'see[ing] the "other"--whether aperson, people or nation--not just as some kind of instrument . . . butas our "neighbor," a "helper" (cf. Gn. 2:18-20), to be made a sharer ona par with ourselves in the banquet of life to which all are equallyinvited by God' Solicitudo Rei Socialis, para. 39."
2. "Greater income disparity can make it harder to have economic and social mobility."
3. "Expenditure cascades" exacerbate the fincancial burdens on the lower classes. An expenditure cascade occurs when the spending of the rich results in increased spending of the poorer classes, even though their wealth hasn't increased.