From Pope St. John Paul II’s encyclical Fides et Ratio (1984):
In our own century too the Magisterium has revisited the theme on a number of occasions, warning against the lure of rationalism. Here the pronouncements of Pope Saint Pius X are pertinent, stressing as they did that at the basis of Modernism were philosophical claims which were phenomenist, agnostic and immanentist.66 Nor can the importance of the Catholic rejection of Marxist philosophy and atheistic Communism be forgotten.67
Later, in his Encyclical Letter Humani Generis, Pope Pius XII warned against mistaken interpretations linked to evolutionism, existentialism and historicism. He made it clear that these theories had not been proposed and developed by theologians, but had their origins “outside the sheepfold of Christ”.68 He added, however, that errors of this kind should not simply be rejected but should be examined critically: “Catholic theologians and philosophers, whose grave duty it is to defend natural and supernatural truth and instill it in human hearts, cannot afford to ignore these more or less erroneous opinions. Rather they must come to understand these theories well, not only because diseases are properly treated only if rightly diagnosed and because even in these false theories some truth is found at times, but because in the end these theories provoke a more discriminating discussion and evaluation of philosophical and theological truths”.69
In accomplishing its specific task in service of the Roman Pontiff’s universal Magisterium,70 the Congregation for the Doctrine of Faith has more recently had to intervene to re-emphasize the danger of an uncritical adoption by some liberation theologians of opinions and methods drawn from Marxism.71
In the past, then, the Magisterium has on different occasions and in different ways offered its discernment in philosophical matters. My revered Predecessors have thus made an invaluable contribution which must not be forgotten.
66 Cf. Encyclical Letter Pascendi Dominici Gregis (8 September 1907): Acta Apostolicæ Sedis [AAS] 40 (1907), 596-597.
67 Cf. Pius XI, Encyclical Letter Divini Redemptoris (19 March 1937): AAS 29 (1937), 65-106.
68 Encyclical Letter Humani Generis (12 August 1950): AAS 42 (1950), 562-563.
69 Ibid., loc. cit., 563-564.
70 Cf. John Paul II, Apostolic Constitution Pastor Bonus (28 June 1988), Arts. 48-49: AAS 80 (1988), 873; Congregation for the Doctrine of the Faith, Instruction on the Ecclesial Vocation of the Theologian Donum Veritatis (24 May 1990), 18: AAS 82 (1990), 1558.
71 Cf. Instruction on Certain Aspects of the “Theology of Liberation” Libertatis Nuntius (6 August 1984), VII-X: AAS 76 (1984), 890-903.
— Fides et Ratio 54