Our appeal, therefore, must not be made to the Scriptures; nor must controversy be admitted on points in which victory will either be impossible, or uncertain, or not certain enough. For a resort to the Scriptures would but result in placing both parties on equal footing, whereas the natural order of procedure requires one question to be asked first, which is the only one now that should be discussed: "With whom lies that very faith to which the Scriptures belong? From what and through whom, and when, and to whom, has been handed down that rule by which men become Christians? For wherever it shall be manifest that the true Christian rule and faith shall be, there will likewise be the true Scriptures and expositions thereof, and all the Christian traditions." (Tertullian, On Prescription against the Heretics, 19; 200 AD)
J.I. Packer deals with this issue of authority in the third chapter of his Fundamentalism and the Word of God. He compares three rival answers: (1) the Evangelical view (Scripture as interpreted by itself), (2) the Traditionalist view (Scripture as interpreted by a living Magisterium in view of Tradition), and (3) the Subjectivist position (Scripture as evaluated in terms of extra-biblical principles by individual Christians).
The difficulty for the "Evangelical view" is that Scripture alone does not interpret Scripture. In a true sense Scripture does interpret Scripture in that certain passages of Scripture help us understand other passages of Scripture. But the problem with the Evangelical position is that "Scripture interprets Scripture" is taken to imply that Scripture alone is sufficient to interpret Scripture, whereas in actuality there must be a human interpreter involved, and that human interpreter has to make interpretive judgments. Among other things, that human interpreter must determine which are the clearer passages. For example, Calvinists take 1 John 2:2 as less clear, and needing to be qualified by John 10, regarding limited atonement. Others take 1 John 2:2 as the clearer passage. The same is true of passages regarding apostasy. The point is that someone has to decide which passages are clearer and which passages are the ones needing clarification/qualification. Scripture itself does not tell us which passages are clearer and which less clear. And the fact is that when people make these decisions about which passages are clearer and which are less clear, they often disagree.
Once we acknowledge the role of the human interpreter, however, then we have to ask ourselves, "Which humans have the ecclesial authority to say with authority what Scripture means?" If we say, "No one", then we are left with a kind of individualism where the sheep are without a shepherd, and each man does what is right in his own eyes, and there is no possibility of Christian unity. But if we acknowledge that some humans have ecclesial authority to give the authoritative explanation of Scripture, then at that point we are no longer in the 'sola scriptura' camp.
There is a more nuanced form of 'sola scriptura' that claims to allow for magisterial authority, but limits infallibility to Scripture alone. However, that form of 'sola scriptura' raises this question: Whose intepretations of Scripture (and thus formulations of doctrine) are authoritative? In other words, Where is the true magisterium. The concern, of course, is that one determines the identity of the "magisterium" based on whether they teach what one presently believes. That is no magisterium at all. That sort of approach effectively eliminates magisterial authority. It is essentially giving lip-service to the idea of magisterial authority, but if one disagrees with anything the 'magisterium' says, one simply leaves and goes somewhere else, choosing or constructing a new 'magisterium'. It treats magisterial 'authority' as contingent on agreement with and consent of the individual self. If the individual ceases to agree with the 'authority', then that 'authority' ipso facto ceases to be his 'authority'. That type of 'authority is not genuine authority; it is authority in name only.
Suppose we agree that the teachings of the Ecumenical Councils are authoritative, at least the first three. What makes them authoritative cannot be just that they happen to teach what lines up with my interpretation of Scripture. That again is individualism giving lip-service to magisterial authority. Likewise, for the same reason, what makes the New Testament canon authoritative cannot be that it matches our own determination of what the NT canon should be. Not only the authoritative interpretation of Scripture but even the canon of Scripture is essentially gone if 'authority' consists in agreement with the individual's beliefs/feelings, etc. One can take out books from the canon or add books to the canon at will, to suit the witness in one's spirit.
So if we do recognize the authority of the early Ecumenical Councils, on what grounds do we do so? The authority of the Ecumenical Councils is necessarily intertwined with the identity and authority of the Magisterium which constituted those councils, including the notion of the episcopal office, valid ordinations and Apostolic succession. If at the time of the early ecumenical councils the bishops were deeply mistaken regarding ordination and apostolic succession, why should their positions on the Trinity or Christology carry any authority? Maybe, the real 'magisterium' in 325 AD was a group of persons who rejected Apostolic succession and episcopal ordination. This 'real magisterium' was outside of the Catholic Church, and is lost to history, and thus the Council of Nicea was composed of people who did not actually belong there. So if one gives up on Apostolic succession and episcopal ordination, it seems to me that one undermines the authority of all the ecumenical councils.
How then should we determine the identity of the true magisterium? We have to try to avoid the sort of circularity mentioned above, i.e. choosing a 'magisterium' based on whatever we happen to believe doctrinally at present. That sort of methodology amounts to constructing a 'god' in one's own image. What are our options? There are two general conceptions of magisterial authority. According to the first, the possession of magisterial authority is ultimately dependent on teaching right doctrine, where what qualifies as right doctrine is determined by each individual. Call that doctrinally-grounded authority (DGA). According to the second, magisterial authority is ultimately dependent on sacramental orders in succession from a divinely appointed authority, and what qualifies as right doctrine is determined by the magisterial authority. Call that sacramentally-grounded authority (SGA).
I see no middle position between these two general categories. Moreover, DGA is in principle no less individualistic than the denial of a magisterium altogether, the very problem I raised above with the view that "Scripture [alone] interprets Scripture". According to a DGA conception of authority, except in cases where I know that I am not practicing what I believe I should be practicing, in any schism, wherever 'I' go, there (in my mind) goes the Church. The ones whom I am leaving are the ones who are (in some sense) excommunicated, since they disagree with what I believe is right doctrine, and therefore they have no magisterial authority. (Notice the parallel to "Ubi Petrus, Ibi Ecclesia".) The fact that like-minded individuals tend to form groups and appoint leaders of their groups does not make the DGA conception of authority any less individualistic, because the ground of the authority in the group is still fundamentally doctrinal agreement with individuals. It simply happens to be that more than one individual is agreeing with the doctrine of this 'authority', and thus giving him 'authority'. In short, it seems that any non-sacramentally grounded conception of magisterial authority is in principle no less individualistic than that form of 'sola scriptura' that denies any magisterium. In other words, if we are trying to avoid the individualism of "Scripture [alone] interprets Scripture", we need a sacramentally grounded magisterial authority.
Of course sacramental conceptions of magisterial authority still require that individuals determine the identity of the true magisterium. So individual choice is not eliminated in SGA. And obviously people can put themselves under a sacramental authority for entirely individualistic reasons, i.e. "because that [sacramental] authority is saying exactly what I believe". But in SGA the criterion for determining the true magisterium is not whether the magisterium agrees with what the individual thinks the true doctrine to be, but whether their sacramental ordination can be traced back to a divinely appointed authority. If in the act of ordaining, one gives what one has received, then either this chain goes back to the incarnate Christ through the Apostles, or it begins with a person who claimed to have received it directly from heaven, e.g. Joseph Smith.
Individualism is a problem not only because of its results (i.e. anarchy, division, and chaos), but because it is a 'model' that fails to provide something that we humans need. That is one way to understand the implied diagnosis in a passage like Judges 21:25, "In those days there was no king in Israel; everyone did what was right in his own eyes." For that reason it seems that Christ would not leave His Church with an authority structure lacking something that Christians need, leaving each individual to determine for himself what is orthodox and what is heresy, in order to determine for himself upon whom magisterial authority has temporarily supervened. It seems more in keeping with the character of the Good Shepherd that He would treat us as a shepherd treats his sheep, not requiring that the sheep first somehow on their own become expert theologians in order to determine who is their rightful shepherd [though obviously simply being a theologian does not necessarily clear up the matter]. Why in that case would they even need shepherds? And how could they become experts without a teacher? A shepherding model in which each sheep chooses a 'shepherd' that is "right in its own eyes" does not seem to be a model that a good shepherd would leave for his sheep or teach to his sheep.
That is one reason why I think DGA (ironically) is not orthodox. Another reason is the Scripture itself, for example, the way David treats Saul, and the way Paul thinks of Ananias (Acts 23:1-5), and the way Jesus describes being in the seat of Moses as the ground of obedience to the scribes and Pharisees (Matt 23:1-3). And another reason is found in the early Church fathers. DGA is just not there, except in heresies like Marcionism, Montanism, or Donatism. What we see in those heresies, besides the heterodoxy itself, is a movement away from SGA to DGA. Such a shift in the conception of authority was the only way these heresies could justify their separation from the Church. In DGA, authority presupposes 'orthodoxy' (where 'orthodoxy' is what seems right in the eyes of the individual). By contrast, for the Church fathers, orthodoxy presupposes SGA. Of course the fathers understood that Church authorities must teach orthodoxy, but the controversies within the Church regarding what is orthodoxy and what is heresy always took place in a context of an SGA hierarchy, such that the authoritative determination of orthodoxy and heresy could come only from the SGA. And the same was true of the discipline of heretical authorities (e.g. Nicolas of Antioch, Marcion of Pontus, Paul of Samosata, Arius of Alexandria, Nestorius of Constantinople, etc.).
A magisterial authority does not have to be unqualifiedly infallible in order to retain its authority. But imagine as a first scenario that no part of the true magisterium, under any mode of teaching, was protected from doctrinal error. Or similarly, imagine a second scenario such that under a certain mode of teaching, the true magisterium was protected from doctrinal error, but that laymen did not know under which mode it was. Either way, every single statement that the true magisterium said would be suspect. Nor would there be available any sure magisterial truths by which to judge any suspect claims. We could not be sure that the canon was correct, nor that any pronouncement from any council or synod was correct. We could not even be sure that the true magisterium's claim "We are the true magisterium" was correct. Every layman would in every case have to decide for himself whether the magisterial teaching was true or false. So if either scenario were true, there could essentially be no functioning magisterium. Each individual would have to decide for him or herself what is doctrinally true and what is doctrinally false, regarding any teaching or claim coming from the magisterium. And that kind of situation is indistinguishable from the individualism that altogether denies any magisterium or any magisterial authority. So neither of those two scenarios can be true if there is a true magisterium. In other words, a true magisterium requires for its existence as such, at least under some known mode of declaration, divinely guaranteed protection from doctrinal error.
If the SGA had no such divine promise of protection from doctrinal error, then either the SGA would necessarily reduce to DGA, or we would be required to follow the SGA no matter how false and evil its teachings. With that divine promise, however, we can know where to plant our feet with respect to orthodoxy and heresy, and know that while error may infect the SGA, error can never overcome it; it will be guided into all truth. So the only two options are SGA with such a divine promise, or DGA. In other words, if DGA is obviously false, then almost by logic alone we can know that there must be such a divine promise.
This distinction between the DGA conception of church authority, and the SGA conception of church authority can be seen in the following quotation from a Touchstone article by Fr. Neuhaus titled, "That They May Be One".
"[T]here are two kinds of Christians: those whom I would call ecclesiological Christians, and those for whom being a Christian is primarily, if not exclusively, a matter of individual decision. There are those for whom the act of faith in Christ and the act of faith in the Church is one act of faith. And those for whom the act of faith in Christ is the act of faith, and the act of faith in the Church, if there is one, is secondary, or tertiary, or somewhere down the line."
The distinction Neuhaus makes between the two kinds of Christians corresponds to the two conceptions of church authority that we discussed earlier: sacramentally-grounded authority (SGA) and doctrinally-grounded authority (DGA). In the DGA conception, one determines which local community of believers (and/or denomination) to join based on how compatible its beliefs and practices are with one's own interpretation of Scripture. Those for whom being a Christian is "primarily, if not exclusively, a matter of individual decision" have a DGA conception of church authority, and cannot make sense of Augustine's statement that "He cannot have God for his Father who does not have the Church for his mother". For them the church is at best a nursemaid, not a mother.
By contrast, the sacramental conception of church authority makes perfect sense of Augustine's statement because an ecclesiological Christian recognizes that we receive salvation through the Church. This does not mean that one does not receive salvation through Christ. Christ has established the Church to be the means by which He mediates salvation to believers, through the sacraments. That is why "Ex Ecclesia, Nulla Salus" only makes sense within a sacramental conception of the Church. (It would be trivially true in any reduction of the Church to the set of all believers.)
But these two ways of thinking cannot mix. They are fundamentally incompatible with each other. Any attempt to mix them will result in an ad hoc position that in essence reduces to DGA.
Why is that? Because for the "individual decision" Christian, the essence of the church is doctrinal, while for the ecclesiological Christian the essence of the Church is sacramental. The "individual decision" Christian is examining the various denominations thinking, "Who comes closest to teaching what I think is right?" The ecclesiological Christian is asking, "For which body of believers would it be true that my having faith in them would be the same act as having faith in Christ?" He might also be asking, "Which body of believers has the authority to determine universally [for all believers] what is orthodoxy and what is heresy?"
There is simply no way to reconcile these two notions of authority because: (1) no man can have two masters -- DGA essentially makes the individual the authority, while SGA recognizes the magisterium as the authority, and (2) DGA makes conformity to one's own interpretation of Scripture the determining factor in locating the Church while SGA makes sacramental succession the determining factor.
Notice that the ecclesiological Christian is asking questions that are intrinsically more fundamental than those asked by the "individual decision" Christian, because questions of doctrine stand or fall on the issue of church authority, as I pointed out in the quotation from Tertullian cited above. That is precisely why it seems unwise to set aside the issue of authority and devote oneself to working out a systematic theology, or even some particular theological question. Only if there were no sacramental church authority would it be proper for me to do such a thing. Only if there were no sacramental church authority would it be true that the determining factor in deciding where I should worship is whether the community in question shares my interpretation of Scripture. But if there is a sacramental church authority, then all my theological musings should be done with its determinations and rulings in view. That is why just about any other theological issue can be postponed, but not the issue of ecclesiastical authority. That same order also applies to our ecumenical efforts.
Recently over at Pontifications Fr. Alvin Kimel posted an excellent discussion (scroll down to section XVII) on church authority. There he brings out this same problem within Anglicanism, claiming that it is an "incoherent position". He writes, "Anglo-Catholics do not notice the problem because they are living off the patrimony and authority of the pre-Reformation Church. Anglo-Catholicism is essentially parasitic, both theologically and ecclesiologically." He shows that without an authoritative magisterium, a communion fundamentally reduces to individualism and private judgment. Over time, any community held together by an ad hoc position such as this will eventually break down to what it is in essence. In other words, that community which is individualistic in essence, even if temporarily and accidentally sustained by past authority and present agreement, will eventually manifest the individualism that it is, and decay by fragmentation into further personalized and particularized communities.