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 supreme authority of the State ought, therefore, to let subordinate groups handle matters and concerns of lesser importance, which would otherwise dissipate its efforts greatly. Thereby the State will more freely, powerfully, and effectively do all those things that belong to it alone because it alone can do them: directing, watching, urging, restraining, as occasion requires and necessity demands. Therefore, those in power should be sure that the more perfectly a graduated order is kept among the various associations, in observance of the principle of “subsidiary function,” the stronger social authority and effectiveness will be the happier and more prosperous the condition of the State.
First and foremost, the State and every good citizen ought to look to and strive toward this end: that the conflict between the hostile classes be abolished and harmonious cooperation of the Industries and Professions be encouraged and promoted.
The social policy of the State, therefore, must devote itself to the re-establishment of the Industries and Professions. In actual fact, human society now, for the reason that it is founded on classes with divergent aims and hence opposed to one another and therefore inclined to enmity and strife, continues to be in a violent condition and is unstable and uncertain. — from Quadragesimo Anno (1931)