By Fred Kammer, S.J.
In 1931, in the encyclical Quadragesimo Anno, Pope Pius XI introduced a critically important Catholic social teaching concept, one which has remained current in political debates today. In his discussion of the social order, he stated the principle:
As history abundantly proves, it is true that on account of changed conditions many things which were done by small associations in former times cannot be done now save by large associations. Still, that most weighty principle, which cannot be set aside or changed, remains fixed and unshaken in social philosophy: Just as it is gravely wrong to take from individuals what they can accomplish by their own initiative and industry and give it to the community, so also it is an injustice and at the same time a grave evil and disturbance of right order to assign to a greater and higher association what lesser and subordinate organizations can do. For every social activity ought of its very nature to furnish help to the members of the body social, and never destroy and absorb them. 
The principle, known as subsidiarity, recently has been invoked—wrongly—to advocate federal block grants to states, slashing welfare programs for needy families, and unregulated free markets.