What gives? still making up doctrines and dogma’s of the infallible sort, 1900 plus years after Christ?
I don’t get it, what’s next?
The assumption of Peter?
No - defining them 
As to the
rightfulness of doing so, & the objections from:
- I think they can be deprived of their main force, if one thinks of Tradition as the memory of the Church; IOW, not as something inert, like a row of reference books, but as a living faculty of the Church, considered as Christ mystically present & active among the nations.
IOW, the Spirit-guided Church could - if that way of thinking about the Church is a valid one - be thought of as rummaging through her memory throughout the centuries, asking herself whether such-&-such an idea is part of the Gospel committed to her as her rule of life & her message. Definitions of dogma, would then be like the convictions men reach after long thought; her processes of thought take a bit longer, because the Church is not an individual human being, but a corporate person composed of individual human beings.
Objection: how does one know, in one’s heart & conscience, before God, that doctrine X is really & truly part of God’s truth ? This is where faith comes in. The question arises for the Assumption - & also for the Deity of Christ, His Messiahship, his Ascension, & pretty well everything else people believe as God’s Truth.
How do we
know the Bible is true ? The OT, taken as a literary artifact (for it is that at least), is pretty much like a lot of other texts of the same age - proverbs were not known in Israel alone; the Egyptians & Sumerians had theirs too; examples of such likenesses could be multiplied. In fact, of course, the Bible has an unique status as the Word of God. But that is a
theological, faith-guided, God-guided judgement - it is
not based on the historical, cultural, detail of the OT. Only God can give certainty about what the Bible is; & what a thing is, should not be confused with questions about what it is made of (as C.S. Lewis points out).
As for the Assumption - the historical details of the controversies about it do not tell us anything about its theological or doctrinal status; what is decisive, is that it has been defined. That does not mean it was not true before, but that it was not so clearly discerned to be true before. It cannot be proved, & does not need to be - one either has eyes to see it as true, or not: just as with the Bible, or with the identity of Christ.
But supposing we are deceived ?
Why should that possibility apply to a Papal text in 1950 AD - & not to the texts about the Resurrection ? The Apostles were men, just as Pius XII was. If we look at them without the gift of faith, there is no more reason to treat what they say as of greater significance than we would a text about other religions of their time. and this faith, is no different from what is need for belief in the Assumption. Were the NT writers regarded as uniquely authoritative in their life-times ? St.Paul’s critics did not view him as “Paul, Apostle to the Gentiles, Saint & Martyr” - appreciation of his being all that, required time. He was just another Christian, while he lived. Appreciation of things often requires distance from them - whether from St.Paul; or from the first Coming of Christ, which is the cause of the Assumption
Either God is as active, omnipotent, truthful in 1950 AD as He was in 30 AD - or He is not. In no way does this imply any “continuing revelation”, gutting of the Bible, or the inspiration of Catholic teaching.
As for the
objection from lateness - lateness is a matter of perspective. If the Church lasts 100,000 years, a mere 1900 years after its birth is unlikely to seem late. If OTOH the Second Coming occurs in the next week, the objection will seem weightier. When it is to be - God knows
More needs to be said: there are plenty of other objections - but I hope that helps
