Humani generis is a papal encyclical that Pope Pius XII promulgated on 12 August 1950 "concerning some false opinions threatening to undermine the foundations of Catholic Doctrine". Theological opinions and doctrines known as Nouvelle Théologie or neo-modernism and their consequences on the Church were its primary subject. Reginald Garrigou-Lagrange (1877–1964), professor of the Pontifical University of Saint Thomas Aquinas Angelicum, is said to have been a dominant influence on the content of the encyclical.
This deposit of faith our Divine Redeemer has given for authentic interpretation not to each of the faithful, not even to theologians, but only to the teaching authority of the Church.
In Humani generis, Pope Pius held a corporate view of theology. Theologians, employed by the Church, are assistants, to teach the official teachings of the Church and not their own private thoughts. They are free to engage in all kinds of empirical research, which the Church will generously support, but in matters of morality and religion, they are subjected to the teaching office and authority of the Church, the Magisterium.
The most noble office of theology is to show how a doctrine defined by the Church is contained in the sources of revelation, … in that sense in which it has been defined by the Church.
Humani generis is critical of some trends in modern theology, but does not mention or attack individual opinions or even groups of dissenting theologians; possibly because of the much larger, still looming power issue of who teaches authoritatively the Catholic faith: Bishops, as successor to the Apostles; or Theologians, who have constant access to relevant information and research tools.
The Pope later refers to a new axiom, a new intellectual current, a new public mood within the Church, and, new behaviour patterns of its members. He asked his fellow bishops, to heal this “intellectual infection”, which should not be allowed to grow.
The Church teaches that God can be known with certainty from the created world with human reason. Yet in the historical conditions in which he finds himself, man experiences many difficulties in coming to know God by the light of reason alone: This is why Humani generis begins with a recognition of several obstacles to seek and find God by the light of reason alone:
Though human reason is, strictly speaking, truly capable by its own natural power and light of attaining to a true and certain knowledge of the one personal God, who watches over and controls the world by his providence, and of the natural law written in our hearts by the Creator; yet there are many obstacles which prevent reason from the effective and fruitful use of this inborn faculty. For the truths that concern the relations between God and man wholly transcend the visible order of things, and, if they are translated into human action and influence it, they call for self-surrender and abnegation. The human mind, in its turn, is hampered in the attaining of such truths, not only by the impact of the senses and the imagination, but also by disordered appetites which are the consequences of original sin. So it happens that men in such matters easily persuade themselves that what they would not like to be true is false or at least doubtful.
This is why man stands in need of being truthfully enlightened by God's revelation.
Having thus established a main principle, the encyclical continues with a review of the philosophical currents of modern culture and their potential and dangers in light of divine revelation of faith in the distinct levels. It reviews recent theological, philosophical and scientific developments.
In describing erroneous development in the Catholic Church after World War Two, the encyclical does not mention names, nor does it accuse specific persons or organization. Nouvelle Théologie in France and its followers in other countries increasingly viewed Catholic teaching as relative. It departed from traditional neo-Thomism using relativistic historical analysis and engaging philosophical axioms, such as existentialism, or positivism. Nouvelle Théologie scholars expressed Catholic dogma with concepts of modern philosophy, immanentism or idealism or existentialism or any other system. Some believed, that the mysteries of faith cannot be expressed by truly adequate concepts but only by approximate and ever changeable notions. Pius has some sympathy for the need to deepen and more precisely articulate Church doctrine:
Everyone is aware that the terminology employed in the schools and even that used by the Teaching Authority of the Church itself is capable of being perfected and polished; and we know also that the Church itself has not always used the same terms in the same way. It is also manifest that the Church cannot be bound to every system of philosophy that has existed for a short space of time. Nevertheless, the things that have been composed through common effort by Catholic teachers over the course of the centuries to bring about some understanding of dogma are certainly not based on any such weak foundation. These things are based on principles and notions deduced from a true knowledge of created things. In the process of deducing, this knowledge, like a star, gave enlightenment to the human mind through the Church. Hence it is not astonishing that some of these notions have not only been used by the Ecumenical Councils, but even sanctioned by them, so that it is wrong to depart from them.
Pius pleads with the “rebels” not to tear down but to build up. He demands, not to neglect, or to reject, or devalue so many and such great resources which have been conceived, expressed and perfected over the centuries. A new philosophy like existentialism, he says, is a poor and unstable basis for the theology of the Church.
Today, like a flower of the field in existence, tomorrow outdated and old-fashioned, shaken by the winds of time.
The encyclical took up a nuanced position with regard to evolution. It distinguished between the soul, held as created divinely, and the physical body, whose development may be subject to empirical and prudent study:
...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. 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.
The encyclical does not endorse a comprehensive belief in evolution, nor its outright rejection, because it deemed the evidence at the time not convincing. It allows for the possibility in the future:
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.
The position delinking the creation of body and soul has been more recently confirmed by Pope John Paul II, who highlighted additional facts supporting the theory of evolution half a century later.
While the factual basis for creationism should be researched further, the encyclical issues a clear no to another scientific opinion popular at the time, polygenism, the scientific hypothesis that mankind descended from different groups of original humanoid animals (that there were many groups of Adams and Eves).
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 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.
A final critique is issued against negative interpretations which downgrade the Old Testament to historical half-truths. Some Catholic theologians
place these scriptures on a par with myths or other such things, which are more the product of an extravagant imagination than of that striving for truth. The Book of Genesis both states the principal truths which are fundamental for our salvation, and also gives a popular description of the origin of the human race and the chosen people.
Humani generis encourages further research, taking into account and respecting the holiness of the Old Testament scriptures to Jews and Christians alike.
Pope Pius XII, who usually employs diplomatic and carefully measured language in his writings, is convinced of the serious nature of those opinions threatening to (to quote the encyclical's subtitle) "undermine the foundation of Catholic doctrine," a most unusual tone for this pontiff.
Philosophy and theology are the main topics of this encyclical. But it extends further into the realm of culture and science. The encyclical is a document with firm distinctions between right and wrong, good and bad. Pius XII is convinced about the indivisibility and timeless nature of truth. The encyclical is flexible in all areas of scientific research, which do not intrude into, or exclude theology. It demands respect for the intellectual achievements of past generations, which were equally intelligent, but is not afraid to face a future with new questions and improvements. Humani generis generated much discussion at its time. It reflects many conservative positions of the Pope, but also his openness to science and new developments. It reflects his belief: "It is the primary duty of a Christian, to convince those who consider themselves modern, that human nature should not be interpreted with systematic pessimism nor with shallow optimism."
Let them strive with every force and effort to further the progress of the sciences which they teach; but let them also be careful not to transgress the limits which We have established for the protection of the truth of Catholic faith and doctrine. With regard to new questions, which modern culture and progress have brought to the foreground, let them engage in most careful research, but with the necessary prudence and caution; finally, let them not think, indulging in a false "irenism," that the dissident and the erring can happily be brought back to the bosom of the Church, if the whole truth found in the Church is not sincerely taught to all without corruption or diminution.