Here are my two cents on the new vs. old (relatively speaking...we're only talking about the last 50 some odd years, less even) views of the RCC regarding non-Catholics.
(I will apologize right now for the length of this post - I know it's quite long, but I'm trying to regurgitate my entire understanding of this issue)
For many centuries (certainly since the rise of scholasticism in the west), the RCC understood sacramental validity as involving three things;
- valid form
- valid matter
- valid intent
Thus, for a "valid baptism" you needed water, the proper three-fold pouring (or immersion), and the intention to truly baptize the person in question (or at the very least, as it came to be formulated, "to do what the Church does when she baptizes").
Given this, many RC guides that I've read (some of them definatly pre-Vatican II) go so far as to say that even a non-baptized person, in the case of an emergency, could baptize someone. Example: a new born infant is in danger of dying, the Jewish doctor could be told how Roman Catholics baptize, and baptize the child, so long as those "three standards" were met. Further, generally the same idea was applied to non-RC bodies (since most confessional Protestants, and the Orthodox, were understood by the RCC to use the proper method of baptizing.)
The wrinkle in this though, was the issue of "intent." This is why, prior to Vatican II, it was still common for many converts to Catholicism from non-RC groups to be at least "conditionally baptized" upon their conversion (and also subject to making a confession, in which "conditional absolution" was offered, prior to the conditional baptism.) The practice of "conditional baptism" has no parallel that I am aware of in Orthodoxy, but rather is an outgrowth of RC sacramental theology.
So put in basic terms, there were common doubts that non-Catholics could (or at the very least, commonly did) form the proper "intent" when otherwise
forms of baptism. The idea behind a "conditonal" baptism, was to enter a clause into the baptismal formula, where the priest would basically be saying "If (such and such) is not
in fact baptized, I baptize him in the Name of the Father, and the Son, and the Holy Ghost." The same went for the "conditional absolution" offered to adult converts in such cases (thus, if they were "really baptized", then the absolution was real; if they were not, it was not.)
What fundamentally changed at Vatican II, was the official removal of such doubts in the case of most non-RC bodies, at least where the "proper form" was being used (though this doesn't apply to all groups; for example, as far as I know the Mormons use the proper form, but the RCC doesn't recognize their baptisms.) I'm not sure what logically justified this more optimistic appraisal of the "intentions" of non-RC groups, but this is what occured.
It's been my experience, that generally groups like the SSPX or other Papally estranged Latin "traditionalists", do not share this new optimism - thus, I know they conditionally baptize most converts from Protestantism (I do not think they would in the case of someone coming from an Orthodox background, but I do not know this from repute or first hand knowledge), and in many cases, I know it is becoming common that they will even conditionally baptize people coming from the Novus Ordo (for a long time the SSPX was already conditionally confirming such people, due to Archbishop Lefebvre's criticisms of the major changes made to the RC rite of confirmation) - I suppose this reflects their (the Latin traditionalists) understanding that the "RC mainstream" is moving further, and further away from what they believe to be "Catholic truth", and becoming all but declared aliens to the Roman Catholic Church.
What also changed dramatically with Vatican II (and perhaps this is more important) was the appraisal of the "worth" of such "valid baptisms". For you see, there were quite a few schoolmen (above all, Thomas Aquinas) who believed that while it was possible for those separated from the RCC to have "valid sacraments" (even valid priesthood and rites which could only be performed by such valid priests), that such "valid sacraments" were in fact of no benefit to those not in communion with Rome. This is the distinction (which definately does exist, at least in old RC theology) between the "character" of the sacrament (which exists, so believe the RC's, in the cases of baptism, confirmation, and holy orders), and the grace thereof, or the operative validity of the sacrament, and it's ability to confer grace.
In short, Thomas Aquinas (and many others) would say that while schismatics could confect a "valid eucharist" (Christ would become really present, and the oblation would be made), this would not communicate "sanctifying grace" to those outside of the Church. If anything, they were in possession of "stolen goods" and were committing sacrelige.
This distinction (validity vs. benefitting from them) for all purposes dissolves in the documents of Vatican II; no doubts are expressed regarding the remission of sins for non-RC's who are baptized as adults (or that children growing up in such groups will somehow "fall out of grace" after reaching the age of reason). No doubts are expressed either about the ability of these people to benefit from their materially "schismatic" rites.
What is even more interesting, is the unquestioned acceptance by the RCC of those sacraments (among non Roman Catholics) which Roman Catholic teaching unambigiously states require "juristiction" to be "confected validly" - these would be "holy matrimony" and "confession."
RC ecclessiology holds that the Pope of Rome, holds in his hands, all juristiction over the entire cosmos, ecclessiastically speaking. Bishops in communion (subordinate) to him, receive their juristiction explicitly/implicitly from him, over their narrowly defined diocese. In turn, they can give of this juristiction, to the clergy under their care.
This "juristiction" is what gives RC clerics (in their view) the "right" to rule and govern the members of the church (that are within their province.)
According to RC teaching, the sacraments of matrimony and confession, to be valid, require this "juristiction" on the part of the priest celebrating them. Without this, though they may have everything else (valid priesthood, valid intent, valid ritual, etc.), no "sacramental marriage" comes into existance, nor does any absolution occur in the case of confession. While other sacraments require "juristiction" to be celebrated licitly (lawfully), they do not need
this to be celebrated "validly."
Well, this begs an important question - how can the RCC now not only recognize the marriages and confessions (in the case of the Orthodox, Copts, Old Catholics, etc.), but even allow under some rather broadly stated circumstances, their own faithful to participate in them (I know the 1983 code of canon law, allows this in the case of confession)?
I would think, from an RC view, the implicit answer is that the Pope is basically "granting juristiction" (in his eyes) to all of these groups to do these things. I know in the past, this type of juristiction was narrowly granted in emergency cases (for example, even a defrocked Latin priest, or Orthodox Priest, could, from the RC view, hear the confession of a dying Catholic.) But this sweeping allowance either amounts to a new, general "granting of authority" by the Popes, or some sort of dissolving of Papal claims. I'm inclined that if push came to shove, it's the former and not the latter, as Rome has definatly not done or said anything to give up this.
Rather, this is an example of Rome's offers to "practice the Papacy in a different, more liberal way" (to accomodate other groups they hope to bring into union with them); not really renegging on anything, but simply (within their own dogmatic confines) trying to be as accomodating as possible.
Of course, that last paragraph is just my conclusion - I don't think Rome itself has officially "connected the dots" on this one.
This non-questioning, sweeping approval of the sacraments of most groups (in so far as they practice them), of course has a logical consequence which the RCC was also keen to promote in the Vatican II documents - that these non-Catholic groups (or in the case of the Protesants, the individuals) were in a real way, already "part of the Church" by virtue of their baptism, "mere Christianity" style profession of faith, and in the case of some groups (like the Orthodox or Copts) preservation of the "aposotlic succession" as Rome understands such things.
Thus, as far as the modern Vatican is concerned, we're all "one church" already - the question then is one solely of charity and administrative unity, not a real matter of being "outside" of what the Latins believe to be "the Church."
It would seem, if forums like this are any indicator, that an increasing number of people from Orthodox backgrounds are thinking the same way.
This is a very interesting subject, since I think many "obedient Catholics" (basically conservative folks, but who are not involved with "dissident" groups like the SSPX) are not really up to speed on what the documents of Vatican II, or the current Papacy, really thinks on this matter. You can particularly see this in the popular "Catholic apologetists" (who will remain nameless...I think most of you are quite familiar with the key players anyway), some more so than others - they seem to be living in something of a quasi "pre-Vatican II"/"Radio Replies" era time warp.
Case in point: I know from my own past experiences, that many of these "apologists" are quite annoyed with (putting it mildly) groups like the SSPX, and will often point out precisely why the confessions and marriages celebrated by their clergy are in fact "invalid." Yet it is quite obvious that Rome doesn't think this way - for even though the SSPX is not on the "ecumenical index" (which identifies the type of groups the Vatican II documents are refering to as being in "imperfect communion with the Holy See"), I do know that when the Campos group (in Brazil - the Priestly Fraternity of St.John Vianney...basically a local Brazillian equivelent to the SSPX, whose founder was in fact in cahoots with Marcel Lefebvre) was recently received back into the RC fold, there was no question of the "validity" of the marriages of people who had been a part of this group prior to it's re-union with Rome (no one was "re-married" as it were.)
It's safe to say, that much has changed in the RCC in the last fourty years in ecclessiological matters; certainly a lot has changed since the days of Pope Boniface VIII's Unum Sanctum
(which basically consigned every person, dog, rock, tree, and insect not under Rome's authority to hell), and the "dogmas" of the Council of Florence, to be sure. Of course, Rome is always careful to offer some (typically strained) means to reconcile all of these things...but I think it's quite apparent to most sane people, that at the very least the "spirit" of those past teachings is being undermined (despite the pharisaical reconciliation of all of it.)