Humani Generis (1950) is Pope Pius XII’s appeal for Catholic theology and philosophy to resist confusions that, in his view, lead to error about God, doctrine, and the Church’s authority. He argues that while reason can know God and the natural law, human limitations and moral obstacles make divine revelation “morally necessary” for firm religious and moral certainty. ¹ He then identifies several contemporary trends—especially certain interpretations connected with evolution, existentialism, and historicism—and he warns against theological “novelty” that weakens or relativizes dogma by undermining the living teaching authority of the Church. ¹

Summary of the document’s main argument

The problem: disagreement, error, and the limits of reason

Pius XII begins by noting that disagreement and error in moral and religious matters are a long-standing sorrow in the world, “especially today,” when Christian principles are being attacked. ¹ He then explains why such error persists: although “absolutely speaking” human reason can reach true knowledge of God and natural law, there are practical obstacles—sensory/imaginative distraction and the effects of sin—that prevent reason from using its power effectively. ¹

Because of these obstacles and the need for self-surrender in order to live certain truths, divine revelation is presented as “morally necessary” so that truths not naturally beyond reason’s reach may be known with “firm certainty” and freedom from error. ¹

The need for the credibility of faith—and the role of refusal

He also addresses why some people struggle to judge the credibility of the Catholic faith even when there are external signs sufficient for certitude by reason: people can resist the evidence out of “prejudice or passion or bad faith,” and they may even refuse impulses of grace. ¹

Specific trends he considers dangerous

Pius XII points to “principle trends” among some scholars outside the Church, including the claim that evolution (which he says is not “fully proved” even in natural sciences) explains the origin of all things, and the adoption of “monistic and pantheistic” ideas (which he links to the denial of a personal God). ¹

He connects these “fictitious tenets” to a broader philosophy that rejects what is “absolute, firm and immutable,” and he names “existentialism” as rivaling idealism/immanentism/pragmatism—because, as he describes it, it focuses on individual existence while neglecting immutable essences. ¹ He also mentions “a certain historicism” that, by valuing only events in a person’s life, undermines the foundations of truth and absolute law—especially for Christian dogmas. ¹

A theological and pastoral danger: novelty and “eirenism”

Pius XII sees a pattern: some people return from rationalism to divine revelation, but then they “diminish the value of human reason” and “spurn the teaching office of the Church.” ¹ He argues that such an attitude is contrary to Scripture and, in practice, can demonstrate—perhaps unwillingly—why a “living Teaching Authority” is necessary. ¹

He then describes a more concealed danger: an “imprudent ‘eirenism’”—a desire to set aside divisive questions to achieve unity. In his view, some use this “barrier” language for the hope of reconciling things opposed in the field of dogma, even at the cost of destroying what supports the integrity of the faith. ^{1 1}

The core doctrinal issue: dogmatic relativism

He then gets very specific about what he thinks is happening in theology: some want “to reduce to a minimum the meaning of dogmas” and “free dogma” from established terminology and philosophical concepts, hoping that once dogma is stripped of what they consider “extrinsic” to revelation, it can be gradually assimilated with the ideas of those separated from full communion. ¹

He argues that the result is essentially “dogmatic relativism”—even if some claim they are merely expressing mysteries differently with “approximate and ever changeable notions.” ¹ He states plainly that efforts to treat dogma this way end up weakening it until “dogma itself [is] a reed shaken by the wind.” ¹

The Church’s authority and the status of theological methods

Pius XII warns that contempt for the resources developed through centuries under the Church’s guidance leads to weakening speculative theology, because it can be treated as lacking certainty. ¹ He also warns that some move from despising scholastic theology to neglecting or even contempt for the Teaching Authority that approved scholastic theology. ¹

He states the Church’s teaching authority is the “proximate and universal criterion of truth” for theologians because Christ entrusted the deposit of faith (Scripture and Tradition) to it. ¹

He also clarifies how encyclicals are to be received: he distinguishes between the ordinary teaching authority and cases where a Supreme Pontiff deliberately passes judgment on a matter previously disputed—then, according to his mind and will, it cannot remain open for dispute among theologians. ¹

The theologian’s task: sources plus the living teaching authority

Finally, he insists theologians must return to the sources of revelation (Scripture and Tradition) and show how the doctrine of the living teaching authority is contained explicitly or implicitly there. ¹ But he also says that authentic interpretation of the deposit of faith is not entrusted to “each of the faithful” or even to theologians, but to the Church’s teaching authority. ¹

Study guide (questions + key themes)

Key theme: why revelation is “morally necessary.”

• What obstacles does he say prevent human reason from making fruitful use of its natural ability? ¹
• How does he define revelation’s role regarding “firm certainty” and freedom from error? ¹
• What does he suggest about why some people still fail to recognize credibility signs? ¹

Key theme: errors tied to “evolution” and philosophical drift

• How does Pius XII describe the move from evolution-as-explanation to monism/pantheism? ¹
• What connection does he draw between rejecting immutable realities and existentialism/historicism? ¹
• In his view, why do such trends tend to undermine absolute law and dogma? ¹

Key theme: “eirenism” and the unity of believers

• What does he mean by “eirenism,” and what does he fear it will do to dogma? ¹
• What common motive does he acknowledge (zeal for souls) before warning about its danger? ¹

Key theme: dogmatic relativism and changing concepts

• What two moves does he criticize in theology? (a) reducing dogma’s meaning, (b) freeing dogma from established terminology and philosophical concepts. ¹
• How does he describe the “approximate and ever changeable notions” approach? ¹
• What is his image of what happens to dogma when these trends take hold? ¹

Key theme: scholastic theology and the magisterium as criterion of truth

• What does he say happens when some “contempt” for scholastic resources spreads? ¹
• Why is the Church’s teaching office described as the “proximate and universal criterion of truth”? ¹
• How does he link the magisterium with the deposit of faith (Scripture and Tradition)? ¹

Key theme: how to interpret papal teaching (consent and dispute)

• What distinction does he draw about encyclicals—ordinary teaching vs when a pope “purposely pass[es] judgment”? ¹
• What is the implication for whether theologians may continue to treat such matters as “open to discussion”? ¹

Key theme: sources of revelation and authentic interpretation

• What must theologians do regarding Scripture and Tradition? ¹
• Who does he say has been entrusted with authentic interpretation of the deposit of faith? ¹

Practical method for studying

• Mark the document’s “logic chain”: (1) limits of reason → (2) moral necessity of revelation → (3) philosophical errors that reject immutable truth → (4) theological methods that relativize dogma → (5) rejection/undermining of the living magisterium. ^{1 1 1 1}
• Rehearse definitions in your own words, especially:
• “Dogmatic relativism” (dogma’s truth treated as variable/approximately expressed rather than stably held) ¹
• “Eirenism” as he warns it (unity pursued by setting aside or dissolving doctrinal questions) ¹
• “Historicist” thinking that undermines absolute law/truth ¹

Conclusion

At its heart, Humani Generis argues that because reason faces real obstacles, divine revelation is necessary for firm religious and moral certainty; and because some modern philosophical approaches reject what is absolute and immutable, some theological methods drift toward reducing dogma and relativizing it—especially when they weaken dependence on the Church’s living teaching authority. ^{1 1 1}

Creation HW #1

Instructions: Read, understand and be able to recall the major points of the excerpts below. Due date: Prior to our next class on Nov. 1, 2025.

Humane Generis Excerpts Pius 12^th

Given at Rome, at St. Peter's, 12 August 1950, the twelfth year of Our Pontificate.

https://www.vatican.va/content/pius-xii/en/encyclicals/documents/hf_p-xii_enc_12081950_humani-generis.html

accessed 9-30-25

25. It is not surprising that novelties of this kind have already borne their deadly fruit in almost all branches of theology. It is now doubted that human reason, without divine revelation and the help of divine grace, can, by arguments drawn from the created universe, prove the existence of a personal God; it is denied that the world had a beginning; it is argued that the creation of the world is necessary, since it proceeds from the necessary liberality of divine love; it is denied that God has eternal and infallible foreknowledge of the free actions of men - all this in contradiction to the decrees of the Vatican Council.[5]

5. Cfr. Conc. Vat., Const. De Fide cath., cap. 1, De Deo rerum omnium creatore.

Pope Pius XII is saying that certain new theological “novelties” have already produced harmful consequences across many areas of theology. He claims that these novelties include proposals such as:

• that human reason alone, without divine revelation and divine grace, cannot prove the existence of a personal God from the created world;
• that the world had no beginning;
• that creation is necessary (rather than free), because it would follow from God’s “necessary liberality”;
• that God does not have eternal and infallible foreknowledge of human free acts.

He then states that all these positions are contrary to the teachings (or “decrees”) of the First Vatican Council. ¹

[1] Humani Generis, 25. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/25

26. Some also question whether angels are personal beings, and whether matter and spirit differ essentially. Others destroy the gratuity of the supernatural order, since God, they say, cannot create intellectual beings without ordering and calling them to the beatific vision. Nor is this all. Disregarding the Council of Trent, some pervert the very concept of original sin, along with the concept of sin in general as an offense against God, as well as the idea of satisfaction performed for us by Christ. 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.

• Angels: Some question whether angels are personal beings. ¹
• Spirit and matter: Some question whether matter and spirit differ essentially. ¹
• Supernatural order: Some “destroy the gratuity” of the supernatural order, claiming God cannot create intellectual beings without ordering and calling them directly to the beatific vision. ¹
• Original sin: Some pervert the doctrine of original sin. ¹
• Sin as offense against God: Some pervert the concept of sin in general as an offense against God. ¹
• Christ’s satisfaction: Some pervert the idea of satisfaction performed for us by Christ. ¹
• Transubstantiation/Eucharist: Some propose modifying transubstantiation so that Christ’s real presence in the Eucharist is reduced to symbolism—the consecrated species would be only “efficacious signs” of Christ’s spiritual presence and union with the Church. ¹

[1] Humani Generis, 26. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/26

31. 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,"[8] 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.[9]

8. C. I. C. can. 1366, 2.; 9. A.A.S., vol. XXXVIII, 1946, p. 387.; (acts of the apostolic see)

• Future priests should be taught philosophy using St. Thomas Aquinas’ method, doctrine, and principles. ¹
• Aquinas’ method is proven by centuries as especially effective for teaching and for revealing truth. ¹
• Aquinas’ doctrine is said to be in harmony with Divine Revelation. ¹
• Aquinas’ philosophy helps protect the foundations of the faith and produces the safe, useful fruits of genuine progress. ¹

[1] Humani Generis, 31. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/31

36. 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.[11] Some however, rashly transgress this liberty of discussion, when they act as if the origin of the human body from pre-existing and living matter were already completely certain and proved by the facts which have been discovered up to now and by reasoning on those facts, and as if there were nothing in the sources of divine revelation which demands the greatest moderation and caution in this question.

11. Cfr. Allocut Pont. to the members of the Academy of Science, November 30, 1941: A.A.S., vol. XXXIII, p. 506.

• The Church’s Teaching Authority does not forbid research and discussion about evolution, when it concerns the origin of the human body as coming from pre-existent living matter. ¹
• This allowance is compatible with Catholic faith because Catholics must still hold that the soul is immediately created by God. ¹
• Such research/discussion must be carried out by people competent in both human sciences and sacred theology. ¹
• The inquiry must be done with seriousness, moderation, and measure. ¹
• Arguments should be carefully weighed on both sides—reasons for evolution and reasons against it. ¹
• Everyone involved should be willing to submit to the Church’s judgment, since Christ gave the Church the mission to authentically interpret Sacred Scripture and defend the dogmas of faith. ¹
• However, some people act rashly, treating the evolution of the human body from pre-existing living matter as completely certain and fully proven by current facts and reasoning. ¹
• They also act as if divine revelation contains nothing that would require great moderation and caution in this question. ¹

[1] Humani Generis, 36. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/36

37. When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own.[12]

12. Cfr. Rom., V, 12-19; Conc. Trid., sess, V, can. 1-4. (council of Trent)

• When the discussion concerns polygenism, the Church does not grant the same liberty as with permissible hypotheses about evolution. ¹
• Faithful Catholics cannot embrace polygenism in the form that teaches either:
• that after Adam there existed true men who did not originate through natural generation from Adam as the first parent of all, or
• that Adam represents not one first parent but a group of first parents. ¹
• The reason is that it is not apparent how such views could be reconciled with what revealed truth and the Church’s Teaching Authority propose about original sin. ¹
• Original sin is taught as proceeding from a sin actually committed by an individual Adam, and then being passed on through generation to all, so that it is in everyone as one’s own. ¹

[1] Humani Generis, 37. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/37

38. Just as in the biological and anthropological sciences, so also in the historical sciences there are those who boldly transgress the limits and safeguards established by the Church. In a particular way must be deplored a certain too free interpretation of the historical books of the Old Testament. Those who favor this system, in order to defend their cause, wrongly refer to the Letter which was sent not long ago to the Archbishop of Paris by the Pontifical Commission on Biblical Studies.[13] This letter, in fact, clearly points out that the first eleven chapters of Genesis, although properly speaking not conforming to the historical method used by the best Greek and Latin writers or by competent authors of our time, do nevertheless pertain to history in a true sense, which however must be further studied and determined by exegetes; the same chapters, (the Letter points out), in simple and metaphorical language adapted to the mentality of a people but little cultured, both state the principal truths which are fundamental for our salvation, and also give a popular description of the origin of the human race and the chosen people. If, however, the ancient sacred writers have taken anything from popular narrations (and this may be conceded), it must never be forgotten that they did so with the help of divine inspiration, through which they were rendered immune from any error in selecting and evaluating those documents.

13. January 16, 1948: A.A.S., vol. XL, pp. 45-48.             

• The Church says that in historical sciences too, some people overstep the limits and safeguards established by the Church. ¹
• A particular thing the Church deplores is a too-free interpretation of the historical books of the Old Testament. ¹
• Some who support this “too free” approach misuse or misquote a recent letter from the Pontifical Commission on Biblical Studies sent to the Archbishop of Paris. ¹
• That letter clarifies that the first eleven chapters of Genesis do not follow the same historical method used by the best Greek and Latin writers (or by competent modern authors). ¹
• Nevertheless, those chapters truly pertain to history in a real sense, though exegetes must further study and determine how. ¹
• The letter also states that these chapters use simple and metaphorical language suited to a people with limited culture, and they:
• state principal truths fundamental for salvation, and
• give a popular description of the origin of the human race and the chosen people. ¹
• Even if the sacred authors took something from popular narratives (which can be admitted), they did so under divine inspiration, which made them immune from error in their selection and evaluation of those documents. ¹

[1] Humani Generis, 38. https://www.magisterium.com/docs/d8b37939-1f3e-458d-81c4-a47920f792f5/ref/38