As I eagerly await that post, I shall point out that we must all be careful to distinguish between describing what actually went on in various processes of development, which was indeed far wider and richer than logical inference, and describing what it was about the various processes that enabled them to yield genuine developments. I suggest that the latter is the kind of inference I've already described.
Since I think this is exactly the point on which an inferentialist view -- whether Scott's deductivist or Michael's inductivist view -- can only do partial justice to actual development of doctrine, I want to say a few things about why I think the development-making feature in the whole process has to be more than an inference.
The first thing, which I've already mentioned, is the richness or complication of actual development. Newman has a nice passage in a sermon late in his Anglican period that captures the sense of it:
What a remarkable sight it is, as almost all unprejudiced persons will admit, to trace the course of the controversy, from its first disorders to its exact and determinate issue. Full of deep interest, to see how the great idea takes hold of a thousand minds by its living force, and will not be ruled or stinted, but is "like a burning fire," as the Prophet speaks, "shut up" within them, till they are "weary of forbearing, and cannot stay," and grows in them, and at length is born through them, perhaps in a long course of years, and even successive generations; so that the doctrine may rather be said to use the minds of Christians, than to be used by them. Wonderful it is, to see with what effort, hesitation, suspense, interruption,—with how many swayings to the right and to the left—with how many reverses, yet with what certainty of advance, with what precision in its march, and with what ultimate completeness, it has been evolved; till the whole truth "self-balanced on its centre hung," part answering to part, one, absolute, integral, indissoluble, while the world lasts! Wonderful, to see how heresy has but thrown that idea into fresh forms, and drawn out from it farther developments, with an exuberance which exceeded all questioning, and a harmony which baffled all criticism, like Him, its Divine Author, who, when put on trial by the Evil One, was but fortified by the assault, and is ever justified in His sayings, and overcomes when He is judged.
I particularly like the expression, "the doctrine may rather be said to use the minds of Christians, than to be used by them." Michael has responded to this point, however, in the above quotation, so I'll pass on to a point I consider even more important.
One of the important steps in the fight against Nestorianism was the Second Council of Constantinople. Justinian and a number of Eastern bishops became convinced that Nestorianism was drawing strength from the writings of Theodore of Mopsuestia, Theodoret of Cyrus, and Ibas of Edessa; so a council was called to condemn their writings. This was somewhat controversial as the Council of Chalcedon had seemed to clear Theodoret and Ibas of personal involvement in Nestorianism, which is one of the reasons the West opposed the Council until after the fact; but the focus here was on the writings. However, it is noteworthy in being an ecumenical council that explicitly considered the issue of how the Church deals with disputed questions in its sentence:
In order to persuade him, we reminded him of the great example left us by the apostles and of the traditions of the fathers. Even though the grace of the holy Spirit was abundant in each of the apostles, so that none of them required the advice of another in order to do his work, nevertheless they were loathe to come to a decision on the issue of the circumcision of gentiles until they had met together to test their various opinions against the witness of the holy scriptures. In this way they unanimously reached the conclusion which they wrote to the gentiles: It has seemed good to the holy Spirit and to us to lay upon you no greater burden than these necessary things; that you abstain from what has been sacrificed to idols and from blood and from what is strangled and from unchastity.
The holy fathers, who have gathered at intervals in the four holy councils, have followed the examples of antiquity. They dealt with heresies and current problems by debate in common, since it was established as certain that when the disputed question is set out by each side in communal discussions, the light of truth drives out the shadows of lying. The truth cannot be made clear in any other way when there are debates about questions of faith, since everyone requires the assistance of his neighbour. As Solomon says in his proverbs: A brother who helps a brother shall be exalted like a strong city; he shall be as strong as a well-established kingdom. Again in Ecclesiastes he says: Two are better than one, for they have a good reward for their toil. And the Lord himself says: Amen I say to you, if two of you agree on earth about anything they ask, it will be done for them by my Father in heaven. For where two or three are gathered in my name, there am I in the midst of them.
I've added the emphasis where I think it is telling. If I were to summarize my basic reason for thinking that inferentialist accounts of development fall short, I could hardly do better than to point here. The problem with an inference is that anyone can do it; whereas development of doctrine is something only the Church can do. The inferentialist, I think, does capture much of the thought that goes into development; but the development itself can only be accurately characterized if it is characterized in such a way that makes clear why everyone in matters of doctrine requires the assistance of their Christian brothers and sisters. For it is certain that they do. Thus I think it is the inferentialist who has difficulty distinguishing properly between all the things that actually went on in development of doctrine from that about the development that actually makes it a development.
A different way to approach this question but make the same point, I think, is to take a specific example of development of doctrine, namely, the development of the canon of Scripture, one of Newman's centerpiece examples of the fact that development of doctrine cannot be ignored. I suspect it's fairly common to think that the development of the canon proceeded by inference -- the Church looked over various candidates using various criteria, and accepted those that fit the criteria. And it has this going for it, that people in the Church did consider such criteria at various stages of the processes. However, it is clear enough that this is not an adequate account of the development, because by the time people started reflecting on the subject in this way, the canon had already developed (having, in fact, largely solidified for purely liturgical reasons); the inferences about the canon were simply a matter of clarifying confusions about the canon. What the inferentialist is forced to overlook is that what makes development of canon legitimate is that the works in question were committed to the Church by the Spirit as having canonical authority; and this was done in a long, slow communal movement. We have no information about the majority of inferences used. We do not know, for instance, why the second generation of Christians was using the Four Gospels in worship the way they were; we don't know why people started using the epistles in the same way. And we don't have any good, reliable inferentialist account of why the Church would have concluded that these books should have this particular sort of authority, against which opinions should be tested. We can, of course, make our own inferences about the matter, and these inferences can and often do confirm that the choice was good. But these are 'external indications'; they miss entirely one way the Spirit actually works, which is by internal assistance of the whole body of Christ as a body. And it is this way that is most relevant to development of doctrine.
The key element in any adequate account of development of doctrine, therefore, has to be confidelity. Confidelity is, in fact, the key element of any adequate account of doctrine at all. As I noted a long time ago in a somewhat different context, it is what resolves the apparent tension between our absolute certainty in the Resurrection of Christ and our insistence that it was a historical event. The tension only arises because we are tempted to take a purely inferentialist view of the matter, i.e., a view in which what gives us our certainty that the Resurrection doctrine is true are the inferences that we make concluding to it. But if this were so, our certainty would be qualified by the limits of the historical evidence. In fact, however, the certainty is much greater because in their confidelity the community of the faithful is the body of the Risen Christ. This certainty, however, is something only discovered when we come together, which is one reason why coming together is so important for reflection on the Resurrection. The inferences that an inferentialist account notes are very important for individuals in the process of accepting the truth of the Resurrection; but we are not merely individuals but a community, and it is as a community that we have our fundamental grasp of the truth. I think this is generally going to be the case. The inferentialist about development of doctrine identifies legitimate and important things -- namely, guidelines about how individuals may guide themselves with respect to Church doctrine, and combine freedom of thought with fidelity to truth. But, while this certainly plays a role in development of doctrine, it is not what constitutes it as development. It is merely what makes it possible for us as individuals to go with the flow of it (so to speak). It's as if we took a plant and tried to say that its life was a particular type of molecular motion.
So, to recap the point so far, I think the inferentialist account fails to do justice to the (1) complexity and (2) confidelity involved in actual development. I also think it fails to do justice to the (3) creativity involved, since I get the impression from reading up on disputes of doctrine that the ways the Church has been called to handle them have been immensely diverse, each one calling for its own bit of ingenuity, and I am not at all convinced that an inferentialist account can do justice to this. But as this is a tricky one, and would require much more than a blog post to develop properly, I won't say much more about it. There is a fourth problem I see with it, which I will get to in a moment, but first I want to deal with a problem with my own view, one for which I only have a partial answer, due to its difficulty. It is one thing to say that development of doctrine should be characterized in communal rather than individual terms, in terms other than inferential ones, but it is another thing entirely to elucidate this. One of the great attractions of any inferentialist account, whether it is non-ampliative or not, is that there has been a lot of work on inference-related issues over the past 2500 years, producing a vast field of resources to draw upon. Once you identify the key feature of development as, say, a Principle of Non-Ampliation, it becomes fairly clear what sort of things you should look at in order to develop this idea. This is not the case for those of us who take a non-inferentialist view of the matter; we are left with a larger number of puzzles to handle, and a much more difficult account to clarify.
There has been some work done, however, that does at least allow us to lay down some suggestive and promising lines of thought. In particular, there has been an increased interest recently in what we can, following MacIntyre, call 'tradition-constituted inquiry'. MacIntyre divides approaches to inquiry into three kinds: Encyclopaedic, Genealogical, and Tradition-constituted. In the first, theoretical knowledge is cast as transparent inferences from fundamental principles or facts; it is impersonal and universal and disinterested. In the second, theoretical knowledge is cast as expressions of self-interest and the will to power; it is neither impersonal or universal. Both approaches tend to assume that we are caught in a dichotomy between one or the other. There is, however, a third way. To use MacIntyre's words from Three Rival Versions of Moral Enquiry, it is an approach according to which one hlds "that reason can only move towards being genuinely universal and impersonal insofar as it is neither neutral nor disinterested, that membership in a particular type of moral community, one from which fundamental dissent has to be excluded, is a condition for genuinely rational enquiry and more especially for moral and theological enquiry." It is clear, I think, that inferentialist accounts of the development of doctrine fit more comfortably in an Encyclopaedic approach than a tradition-constituted one; at the same time, it is clear that, unless development of doctrine is to be set free-wheeling, independent of any stable truth, a rejection of the inferentialist view would seem to require a tradition-constituted approach.
One of the great strengths of the tradition-constituted approach for considering development of doctrine is that it is telos-guided. As MacIntyre puts it, a tradition-constituted approach draws from the past in order that we may learn how to approach our telos, our end, more adequately. This element of finality is sorely lacking in the inferentialist approach, which treats development of doctrine in purely formal terms. At least, any final cause seems to be extrinsic on an inferentialist view. But I would suggest that the whole point of development is that it has entelechy -- it carries its end inside it, it has a final-causal aspect in its very essence. This is why it is so easy to think of development of doctrine on analogy with organic development, and we begin to see more clearly what Newman's notes of development (as opposed to deterioration) are doing: they are distinguishing between something that carries its purpose inside it (a living tradition) from something that does not (a dead one). In the sermon noted above, Newman notes the feature that marks out heresy, and again we find this organic metaphor:
Its formulae end in themselves, without development, because they are words; they are barren, because they are dead. If they had life, they would increase and multiply; or, if they do live and bear fruit, it is but as "sin, when it is finished, bringeth forth death." It developes into dissolution; but it creates nothing, it tends to no system, its resultant dogma is but the denial of all dogmas, any theology, under the Gospel. No wonder it denies what it cannot attain.
It lacks the principle of life; it has no aptness for 'living and bearing fruit'. Heresy is mechanical, and its change is a mechanical sort of change. But what it attacks is a vibrantly living tradition, because what is carried forward is a purpose, a final causality, a teleology. When the Church considers a claim, its primary concern is never, and has never been, the precise way in which the claim is related to other claims. That does come up as an important (very important!) auxiliary issue; but its primary concern has been how the claim relates to the telos of the Church, Christ our Head and our salvation. What makes Appolinarianism so suspicious, for instance, is that it violates this telos; the fact that it does so is in itself an excellent argument for the conclusion that, however well-supported it might initially seem (whether by deductive or inductive inferences), there is something wrong with that support. So, despite their useful elucidation of many important points, inferentialist accounts, when taken as a whole, lack the life that characterizes development of doctrine, the life the Church has because we have been grafted onto the Vine, because we have been stamped with an image of Christ and His life, death, and resurrection -- an intelligible character -- that gives us a telos and draws us together into one body. On our own we can get muddled or confused about that telos; but together we begin to see more clearly. Thus the conciliar fathers were right: even when we have the right to judge a matter on our own, it is essential to come together in mutual aid; for in matters of dispute about the faith, truth can be found in no other way. It is when we come together as a community in Christ that light shines and shadows flee, and the doctrine of the Church, develops, advances in victory, against heresy and falsehood.
So there are four features of development of doctrine that I think to which I think an adequate account must do justice: (1) richness; (2) confidelity; (3) creativity; (4) entelechy. I think that inferentialist accounts, of whatever kind, and for all their good, fall short on all four points. The alternative I've sketched here -- very sketchily! -- does better, I think, although it requires a vast amount of development. And perhaps that's as it should be.