Reciprocity of Rights and Duties Between Persons
30. Every basic human right draws its authoritative force from the natural law, which confers it and attaches to it its respective duty. Hence, to claim one's rights and ignore one's duties, or only half fulfill them, is like building a house with one hand and tearing it down with the other.
31. Since men are social by nature, they must live together and consult each other's interests. That men should recognize and perform their respective rights and duties is imperative to a well ordered society. But the result will be that each individual will make his whole-hearted contribution to the creation of a civic order in which rights and duties are ever more diligently and more effectively observed.
An Attitude of Responsibility
34. There is nothing human about a society that is welded together by force. Far from encouraging, as it should, the attainment of man's progress and perfection, it is merely an obstacle to his freedom.
Social Life in Truth, Justice, Charity and Freedom
35. Human society, as We here picture it, demands that men be guided by justice, respect the rights of others and do their duty. It demands, too, that they be animated by such love as will make them feel the needs of others as their own, and induce them to share their goods with others, and to strive in the world to make all men alike heirs to the noblest of intellectual and spiritual values.
The encyclical can be found on the Vatican website here.