Dei Filius
Dei Filius is the incipit of the dogmatic constitution of the First Vatican Council on the Catholic faith, which was adopted unanimously, and issued by Pope Pius IX on 24 April 1870.
The constitution set forth the teaching of "the holy Catholic Apostolic Roman Church" on God, revelation and faith.
Content
The dogmatic constitution "deals with faith, reason, and their interrelations".The document begins by observing that "God, the principle and end of all things, can be known with certainty by the natural light of human reason from created things". However, it then explains that, through divine revelation, this knowledge can more easily be attained "with firm assurance, and with no admixture of error".
Faith and reason are seen as complementary. Following Thomas Aquinas, whose guiding thought Philip Egan paraphrases as that "it is the same God who grounds all truth, whether secular or divine, and the truth is ultimately one", Dei Filius said
Name used for the church
The draft presented to the council on 8 March 1870 drew no serious criticism. But a group of 35 English-speaking bishops, who feared that the opening phrase "Sancta Romana Catholica Ecclesia" might be construed as favouring the Anglican branch theory, raised objections to this expression, "Holy Roman Catholic Church". They proposed that the word "Roman" be omitted out of concern that use of the term "Roman Catholic" would lend support to proponents of branch theory. While the council overwhelmingly rejected this proposal, the text was finally modified to read "The Holy Catholic Apostolic and Roman Church".The words "Sancta Romana Catholica Ecclesia" were voted on three separate dates. On the first occasion, when this chapter alone was considered, two votes concerned the opening words. The first was on a proposal by a few English-speaking bishops to delete the word "Romana", thus changing "Sancta Romana Catholica Ecclesia" to "Sancta Catholica Ecclesia". This was overwhelmingly defeated.
The second vote, held immediately afterwards, was on a proposal to insert a comma, so that "Sancta Romana Catholica Ecclesia" would become "Sancta Romana, Catholica Ecclesia". This too was defeated, though not as overwhelmingly as the first proposal.
In a later vote, held on 12 April 1870, the text as a whole, which preserved the same opening words, was approved with 515 affirmative votes and no opposing votes ; but there were 83 placet iuxta modum votes, asking for retouches, many of them regarding the opening words of chapter I.
In view of the reservations thus expressed, the text presented for a final vote and approved unanimously on 24 April changed the order of the words and added "Apostolica", so that "Sancta Romana Catholica Ecclesia" became "Sancta Catholica Apostolica Romana Ecclesia".