It is commonly stated that there have been but 2 “ex cathedra” statements issued in the Church’s history. Those are stated to be: The Immaculate Conception and the Assumption.
I challenge that common reading. I contend that there have been more than 2.
Interesting: Pius IX urges Catholic thinkers to assent to all the dogmas, those taught “by explicit decrees of ecumenical councils or by the Roman pontiffs [plural!] and by this Apostolic See” (DS 2879, Ignatius Press edition). Note that he uses the plural here. He implies that there have been several such ex cathedra teachings. But the Assumption had not yet been taught in this way. Ergo, there are more than 2.
“Name another.” I’ll name two:
Boniface VIII: “We declare, we proclaim, we define that it is absolutely necessary for salvation that every human creature be subject to the Roman Pontiff.” This is an irreformable teaching.
Benedict XII: “By this Constitution which is to remain in force for ever, we, with apostolic authority, define the following: According to the general disposition of God, the souls of all the saints who departed from this world before the passion of our Lord Jesus Christ….”
There are others also. With regard to some there is reasonable dispute as to whether or not they carry that ex cathedra weight. And there is a touch of irony in that.