- Tradition as principal source. Actually, nowhere in the text they cite Scripture as a theological source. Instead, there is constant reference to the tradition of the church, along with the assurance that they have no intention of deviating from this tradition.
It is only consequent, that all further arguments base themselves on "the texts of the Council and those of the Magisterium since the Council."
The Second Vatican Council neither changed nor intended to change this doctrine, rather it developed, deepened and more fully explained it.
This was exactly what John XXIII said at the beginning of the Council. Paul VI affirmed it and commented in the act of promulgating the Constitution Lumen gentium: "There is no better comment to make than to say that this promulgation really changes nothing of the traditional doctrine. What Christ willed, we also will. What was, still is. What the Church has taught down through the centuries, we also teach. In simple terms that which was assumed, is now explicit; that which was uncertain, is now clarified; that which was meditated upon, discussed and sometimes argued over, is now put together in one clear formulation". The Bishops repeatedly expressed and fulfilled this intention.
- Praxis as a less acknowledged source, which is nevertheless present:
In simple terms that which was assumed, is now explicit; that which was uncertain, is now clarified; that which was meditated upon, discussed and sometimes argued over, is now put together in one clear formulation.Actually, the English translation ("that which was assumed") of this quote from Paul VI is somewhat free. The original Latin document reads
Tantummodo, id quod antea solum vitae actione continebatur, nunc aperta etiam doctrina exprimitur; quod usque adhuc considerationi, disputationi, atque ex parte etiam controversiis obnoxium erat, in certam doctrinae formulam nunc redactum est.Note the emphasis (underline inserted by me) on "vitae actione" -- what has only been practised in "real life" before, now has become clearly expressed in doctrine. Thus, Paul VI actually acknowledged the possibility of praxis becoming doctrine. The use of the quote in this new text reiterates the same possibility. Praxis is thus, without an explicit statement, accepted as a second source of theology.