There’s a lot to be said about “development.” Of course, Catholics want to lump everything under the one thing. This is the “word=concept” fallacy.
Dr. William Witt, an Anglican, wrote a bit about Newman and development, and here he defines here identifies two different kinds of development. He cites Mozley, who accuses Newman of using the same word to mean two different things. These he distinguishes as “development 1” and “development 2”:
The language of Nicea is the language of critical realism. Nicea speaks of who the Son of God must be in himself if he is going to be God for us.
Mozley speaks of this kind of development in terms of what I will call “Development 1.” Development 1 adds nothing to the original content of faith, but rather brings out its necessary implications. Mozley says that Aquinas is doing precisely this kind of development in his discussion of the incarnation in the Summa Theologiae.
There is another kind of development, however, which I will call “Development 2.” Development 2 is genuinely new development that is not simply the necessary articulation of what is said explicitly in the Scriptures.
Classic examples of Development 2 would include the differences between the doctrine of the theotokos and the dogmas of the immaculate conception or the assumption of the Blessed Virgin Mary. In the former, Marian dogma is not actually saying something about Mary, but rather something about Christ. If Jesus Christ is truly God, and Mary is his mother, then Mary is truly the Mother of God (theotokos). She gives birth, however, to Jesus’ humanity, not his eternal person, which has always existed and is generated eternally by the Father. The doctrine of the theotokos is a necessary implication of the incarnation of God in Christ, which is clearly taught in the New Testament. However, the dogmas of the immaculate conception and the assumption are not taught in Scripture, either implicitly or explicitly. They are entirely new developments.
The same would be true, of course, for the doctrine of the papacy…
I think it would be important to note here, that whereas for a thousand years the Roman church taught that the papacy was “immediately given”, it has only recently conceded “a continuity of development” with regard to the papacy. (I’ve written plenty about this at the De Regnis Duobus blog, and also here).
Also, William Cunningham wrote a scathing indictment of Newman in his work “Discussions on Church Principles” (available as a Google Book).
He notes that Newman:
…takes care to give no precise and definite statement of what the difficulties are, because this would expose the weakness of Romanism. He rather assumes them as known, and admits, by implication, that they exist. We think it would be right to be a little more specific upon this point, and would therefore remind our readers that the grand difficulty in the investigation of Christianity lies in the palpable contrast between the Christianity of the New Testament and the Christianity of the modern Church of Rome.
Of course, Dr. Witt also outlines Chadwick’s “From Bossuet to Newman,” in which the primary argument against Protestantism changed from “We are the religion that never changes” to “We can change all we want cause we’re in authority.” (Of course, I’ve summarized a bit, but that’s the gist of it.)