From Pope Benedict XVI’s encyclical Caritas in Veritate (2009):
The link between Populorum Progressio and the Second Vatican Council does not mean that Paul VI’s social magisterium marked a break with that of previous Popes, because the Council constitutes a deeper exploration of this magisterium within the continuity of the Church’s life.19 In this sense, clarity is not served by certain abstract subdivisions of the Church’s social doctrine, which apply categories to Papal social teaching that are extraneous to it. It is not a case of two typologies of social doctrine, one pre-conciliar and one post-conciliar, differing from one another: on the contrary, there is a single teaching, consistent and at the same time ever new.20 It is one thing to draw attention to the particular characteristics of one Encyclical or another, of the teaching of one Pope or another, but quite another to lose sight of the coherence of the overall doctrinal corpus.21 Coherence does not mean a closed system: on the contrary, it means dynamic faithfulness to a light received. The Church’s social doctrine illuminates with an unchanging light the new problems that are constantly emerging.22 This safeguards the permanent and historical character of the doctrinal “patrimony”23 which, with its specific characteristics, is part and parcel of the Church’s ever-living Tradition.24 Social doctrine is built on the foundation handed on by the Apostles to the Fathers of the Church, and then received and further explored by the great Christian doctors. This doctrine points definitively to the New Man, to the “last Adam [who] became a life-giving spirit” (1 Cor 15:45), the principle of the charity that “never ends” (1 Cor 13:8). It is attested by the saints and by those who gave their lives for Christ our Saviour in the field of justice and peace. It is an expression of the prophetic task of the Supreme Pontiffs to give apostolic guidance to the Church of Christ and to discern the new demands of evangelization. For these reasons, Populorum Progressio, situated within the great current of Tradition, can still speak to us today.
19 Cf. Benedict XVI, Christmas Address to the Roman Curia, 22 December 2005.
20 Cf. John Paul II, Encyclical Letter Sollicitudo Rei Socialis, 3: Acta Apostolicæ Sedis [AAS] 80 (1988), 515.
21 Cf. ibid., 1: loc. cit., 513-514.
22 Cf. ibid., 3: loc. cit., 515.
23 Cf. John Paul II, Encyclical Letter Laborem Exercens (14 September 1981), 3: AAS 73 (1981), 583-584.
24 Cf. John Paul II, Encyclical Letter Centesimus Annus, 3: loc. cit., 794-796.
— Caritas in Veritate 12