Yes — but only one kind of growth, and the whole dispute is over which kind. This is the question beneath the others: Catholics justify papal primacy, the Filioque, the Immaculate Conception as legitimate developments of the apostolic deposit; the Orthodox charge that they are innovations — additions to “the faith once delivered to the saints.”

The Orthodox objection deserves its full force. The faith is a deposit to be guarded, not a project to be grown; the Church’s office is conservation, not invention. The ecumenical councils explicated what was already held against heresy — they did not reveal new data. And by the famous Vincentian canon, Catholic truth is “what has been believed everywhere, always, and by all” — a test a doctrine first defined in 1854 or 1870 seems to fail on its face. From this angle “development of doctrine” looks suspiciously convenient: a theory published by Newman in 1845, just in time to license precisely the Roman additions the East never received. Florovsky speaks for the Eastern method — theology means acquiring the mind of the Fathers, not evolving toward conclusions they never drew.

But notice what neither side actually holds. Homoousios — the hinge word of Nicaea — is not in Scripture; the Trinitarian and Christological dogmas are stated in post-biblical language; the canon of Scripture itself was settled by the Church over centuries. The Orthodox accept all of this. So the real question is not “may anything develop?” — both sides answer yes — but “what separates legitimate unfolding from corrupting addition?” And here the decisive witness is one both sides claim. The same St. Vincent of Lérins who gave the canon also taught, in the same little book, that there must be real progress in the Church — profectus, not permutatio; growth like a body from infancy to adulthood, the same person enlarged, never transformed into something else — advancing “in the same doctrine, in the same sense, and in the same meaning.” The Orthodox cite Vincent’s chapter 2; Catholics cite his chapter 23; they are one author in one book. “No development at all” is not a Vincentian position either.

That is the Catholic frame, and it concedes the danger honestly. Public revelation closed with the apostles — “no new public revelation is to be expected” (Catechism §66) — yet the understanding of the deposit can grow; Vatican I made Vincent’s rule dogma, insisting dogma advance only “in the same doctrine, the same sense, and the same understanding.” Newman’s Essay then supplies seven tests — chiefly preservation of type and continuity of principles — precisely because a bare appeal to “it developed” proves nothing. The Orthodox are right to warn that “development” can become a blank check, and the Immaculate Conception and papal infallibility are the genuine hard cases where they say the line was crossed. So the Catholic burden is not to wave at a theory but to show continuity of type for each doctrine, one at a time. The theory only frames the question; it never settles a single case on its own.