The Perennial Philosophy is that body of truths certainly knowable from natural reason which is also explicitly or implicitly contained in Divine Revelation and therefore necessary to the proper comprehension of the teachings of the Church. Without the Perennial Philosophy the terminology used by the church in its solemn definitions would have no stable meaning and it would be possible to change the sense of Catholic Dogma by switching philosophies. This was described b Pius X as one of the main tactics of the Modernists. In the 1914 motu proprio Doctoris Angelici he explained:
“The capital theses in the philosophy of St. Thomas are not to be placed in the category of opinions capable of being debated one way or another, but are to be considered as the foundations upon which the whole science of natural and divine things is based; if such principles are once removed or in any way impaired, it must necessarily follow that students of the sacred sciences will ultimately fail to perceive so much as the meaning of the words in which the dogmas of divine revelation are proposed by the magistracy of the Church.”
In order to prevent this Pius X made the content of the Perennial Philosophy far more explicit by issuing 24 Theses defining “the principles of St Thomas”. It is seldom appreciated that Vatican II endorsed both the concept and the content of the Perennial Philosophy as taught by Pius X and later defended by Pius XII (in the 1950 encyclical Humani Generis). The Decree of the Second Vatican Council on Priestly Training Optatam Totius §15 states:
“The philosophical disciplines are to be taught in such a way that the students are first of all led to acquire a solid and coherent knowledge of man, the world, and of God, relying on that philosophical patrimony which is perennially valid and taking into account the philosophical investigations of later ages.”
This provision is embodied word for word in Canon 251 of the Code of Canon Law. In an official response of the 20th December 1965 the Sacred Congregation for Seminaries and Universities stated that the words “perennially valid” refer to “the principles of St Thomas”. As mentioned, twenty five of these were defined in the Decree Postquam Sanctissumus of St Pius X of 27th July 1914. The requirement for those teaching in seminaries and universities to adhere to them in their teaching was then incorporated into the 1917 Code of Canon Law. At the words “perennially valid” in Optatam Totius itself the Council fathers inserted a footnote. It reads:
“Cf. PIUS XII, Litt. Encycl. Humani Generis, 12 aug. 1950: AAS 42 (1950), pp. 571-575.”
This refers to a section of Pius XII 1950 encyclical where he defends the provisions of Pius X. This is what the cited pages 571 to 575 of Pius XII’s Acta for 1950 say:
Some even say that the doctrine of transubstantiation, based on an antiquated philosophic notion of substance, should be so modified that the real presence of Christ in the Holy Eucharist be reduced to a kind of symbolism, whereby the consecrated species would be merely efficacious signs of the spiritual presence of Christ and of His intimate union with the faithful members of His Mystical Body.
Some say they are not bound by the doctrine, explained in Our Encyclical Letter of a few years ago, and based on the Sources of Revelation, which teaches that the Mystical Body of Christ and the Roman Catholic Church are one and the same thing. Some reduce to a meaningless formula the necessity of belonging to the true Church in order to gain eternal salvation. Others finally belittle the reasonable character of the credibility of Christian faith.
These and like errors, it is clear, have crept in among certain of Our sons who are deceived by imprudent zeal for souls or by false science. To them We are compelled with grief to repeat once again truths already well known, and to point out with solicitude clear errors and dangers of error.
It is well known how highly the Church regards human reason, for it falls to reason to demonstrate with certainty the existence of God, personal and one; to prove beyond doubt from divine signs the very foundations of the Christian faith; to express properly the law which the Creator has imprinted in the hearts of men; and finally to attain to some notion, indeed a very fruitful notion, of mysteries. But reason can perform these functions safely and well only when properly trained, that is, when imbued with that sound philosophy which has long been, as it were, a patrimony handed down by earlier Christian ages, and which moreover possesses an authority of an even higher order, since the Teaching Authority of the Church, in the light of divine revelation itself, has weighed its fundamental tenets, which have been elaborated and defined little by little by men of great genius. For this philosophy, acknowledged and accepted by the Church, safeguards the genuine validity of human knowledge, the unshakable metaphysical principles of sufficient reason, causality, and finality, and finally the mind’s ability to attain certain and unchangeable truth.
Of course this philosophy deals with much that neither directly nor indirectly touches faith or morals, and which consequently the Church leaves to the free discussion of experts. But this does not hold for many other things, especially those principles and fundamental tenets to which We have just referred. However, even in these fundamental questions, we may clothe our philosophy in a more convenient and richer dress, make it more vigorous with a more effective terminology, divest it of certain scholastic aids found less useful, prudently enrich it with the fruits of progress of the human mind. But never may we overthrow it, or contaminate it with false principles, or regard it as a great, but obsolete, relic. For truth and its philosophic expression cannot change from day to day, least of all where there is question of self-evident principles of the human mind or of those propositions which are supported by the wisdom of the ages and by divine revelation. Whatever new truth the sincere human mind is able to find, certainly cannot be opposed to truth already acquired, since God, the highest Truth, has created and guides the human intellect, not that it may daily oppose new truths to rightly established ones, but rather that, having eliminated errors which may have crept in, it may build truth upon truth in the same order and structure that exist in reality, the source of truth. Let no Christian therefore, whether philosopher or theologian, embrace eagerly and lightly whatever novelty happens to be thought up from day to day, but rather let him weigh it with painstaking care and a balanced judgment, lest he lose or corrupt the truth he already has, with grave danger and damage to his faith.
If one considers all this well, he will easily see why the Church demands that future priests be instructed in philosophy “according to the method, doctrine, and principles of the Angelic Doctor,” since, as we well know from the experience of centuries, the method of Aquinas is singularly preeminent both of teaching students and for bringing truth to light; his doctrine is in harmony with Divine Revelation, and is most effective both for safeguarding the foundation of the faith and for reaping, safely and usefully, the fruits of sound progress.
How deplorable it is then that this philosophy, received and honored by the Church, is scorned by some, who shamelessly call it outmoded in form and rationalistic, as they say, in its method of thought. They say that this philosophy upholds the erroneous notion that there can be a metaphysic that is absolutely true; whereas in fact, they say, reality, especially transcendent reality, cannot better be expressed than by disparate teachings, which mutually complete each other, although they are in a way mutually opposed. Our traditional philosophy, then, with its clear exposition and solution of questions, its accurate definition of terms, its clear-cut distinctions, can be, they concede, useful as a preparation for scholastic theology, a preparation quite in accord with medieval mentality; but this philosophy hardly offers a method of philosophizing suited to the needs of our modern culture. They allege, finally, that our perennial philosophy is only a philosophy of immutable essences, while the contemporary mind must look to the existence of things and to life, which is ever in flux. While scorning our philosophy, they extol other philosophies of all kinds, ancient and modern, oriental and occidental, by which they seem to imply that any kind of philosophy or theory, with a few additions and corrections if need be, can be reconciled with Catholic dogma. No Catholic can doubt how false this is, especially where there is question of those fictitious theories they call immanentism, or idealism or materialism, whether historic or dialectic, or even existentialism, whether atheistic or simply the type that denies the validity of the reason in the field of metaphysics.
Finally, they reproach this philosophy taught in our schools for regarding only the intellect in the process of cognition, while neglecting the function of the will and the emotions. This is simply not true. Never has Christian philosophy denied the usefulness and efficacy of good dispositions of soul for perceiving and embracing moral and religious truths. In fact, it has always taught that the lack of these dispositions of good will can be the reason why the intellect, influenced by the passions and evil inclinations, can be so obscured that it cannot see clearly. Indeed St. Thomas holds that the intellect can in some way perceive higher goods of the moral order, whether natural or supernatural, inasmuch as it experiences a certain “connaturality” with these goods, whether this “connaturality” be purely natural, or the result of grace; and it is clear how much even this somewhat obscure perception can help the reason in its investigations. However it is one thing to admit the power of the dispositions of the will in helping reason to gain a more certain and firm knowledge of moral truths; it is quite another thing to say, as these innovators do, indiscriminately mingling cognition and act of will, that the appetitive and affective faculties have a certain power of understanding, and that man, since he cannot by using his reason decide with certainty what is true and is to be accepted, turns to his will, by which he freely chooses among opposite opinions.
It is not surprising that these new opinions endanger the two philosophical sciences which by their very nature are closely connected with the doctrine of faith, that is, theodicy and ethics; they hold that the function of these two sciences is not to prove with certitude anything about God or any other transcendental being, but rather to show that the truths which faith teaches about a personal God and about His precepts, are perfectly consistent with the necessities of life and are therefore to be accepted by all, in order to avoid despair and to attain eternal salvation. All these opinions and affirmations are openly contrary to the documents of Our Predecessors Leo XIII and Pius X, and cannot be reconciled with the decrees of the Vatican Council. It would indeed be unnecessary to deplore these aberrations from the truth, if all, even in the field of philosophy, directed their attention with the proper reverence to the Teaching Authority of the Church, which by divine institution has the mission not only to guard and interpret the deposit of divinely revealed truth, but also to keep watch over the philosophical sciences themselves, in order that Catholic dogmas may suffer no harm because of erroneous opinions.
It remains for Us now to speak about those questions which, although they pertain to the positive sciences, are nevertheless more or less connected with the truths of the Christian faith. In fact, not a few insistently demand that the Catholic religion take these sciences into account as much as possible. This certainly would be praiseworthy in the case of clearly proved facts; but caution must be used when there is rather question of hypotheses, having some sort of scientific foundation, in which the doctrine contained in Sacred Scripture or in Tradition is involved. If such conjectural opinions are directly or indirectly opposed to the doctrine revealed by God, then the demand that they be recognized can in no way be admitted.
For these reasons the Teaching Authority of the Church does not forbid that, in conformity with the present state of human sciences and sacred theology, research and discussions, on the part of men experienced in both fields, take place with regard to the doctrine of evolution, in as far as it inquires into the origin of the human body as coming from pre-existent and living matter – for the Catholic faith obliges us to hold that souls are immediately created by God. However, this must be done in such a way that the reasons for both opinions, that is, those favorable and those unfavorable to evolution, be weighed and judged with the necessary seriousness, moderation and measure, and provided that all are prepared to submit to the judgment of the Church, to whom Christ has given the mission of interpreting authentically the Sacred Scriptures and of defending the dogmas of faith.
6. Cfr. Litt. Enc. Mystici Corporis Christi, A.A.S., vol. XXXV, p. 193 sq.
7. Cfr. Conc. Vat., D.B., 1796.
8. C. I. C. can. 1366, 2.
9. A.A.S., vol. XXXVIII, 1946, p. 387.
10. Cfr. St. Thom., Summa Theol., II-II, quaest. 1, art. 4 ad 3 et quaest. 45, art. 2, in c.
11. Cfr. Allocut Pont. to the members of the Academy of Science, November 30, 1941: A.A.S., vol. XXXIII, p. 506.