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".

[5][verification needed] In areas of both "human sciences and sacred theology", the encyclical authorized "research and discussions" where "reasons for both opinions, that is, those favorable and those unfavorable to evolution" were to "be weighed and judged.

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.

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.

The encyclical states the Nouvelle théologie and its followers viewed Catholic teaching as relative, that it departed from traditional neo-Thomism using relativistic historical analysis and engaging philosophical axioms, such as existentialism, or positivism.

A new philosophy like existentialism, "today, like a flower of the field in existence, tomorrow outdated and old-fashioned, shaken by the winds of time",[8] he says, is a poor and unstable basis for the theology of the Church.

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.

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.

[10] 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.

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.