The Second Council of Lyon does, however, address the topic in sufficient detail. It rejects the the use of “co-principle,” understood in at least one sense (i.e., of two spirations), declaring: “Spiritus Sanctus aeternaliter ex Patre et Filio, non tanquam ex duobus principiis, sed tanquam ex uno principio, non duabus spirationibus, sed unica spiratione procedit.” This is not the sense in which I use the term.

Aquinas allows for the use of the term in the sense in which I employ it at Summa theol. Ia, q. 36, a. 4, respondeo & ad 7um but actually prefers the term you have suggested, Ryan and Eric, describing the procession as “pater per filium spirat spiritum sanctum; vel quod spiritus sanctus procedat a patre per filium, quod idem est” (Summa theol. Ia, q. 36, a. 3, respondeo).

I will certainly not continue to use the term co-principle with so great a cloud of witnesses urging (and more than urging in the case of the Council of Toledo) me to do otherwise. I repent of the poor choice of words and thank you for your fraternal correction.

Those who find disagreement with the language “AND” are those who want to keep up schism. If you find a whole bunch of Fathers in the West using the Word “AND.” that should be enough the Satisfy anyone who might have qualms about the orthodoxy of such language.

The words “and” and “through” are liable to misinterpretation, and both can have and heretical meaning, and and orthodox meaning.

Btw Eric the Eastern Catholic are not required to say the Filioque, but they are required to believe it.

To state that the Son is a co-principle with the Father in the procession of the Spirit is not to deny that the Father is without principle; nor is it to deny that the Father is the principle of the Son. It is simply to confirm that there are two principles of the Spirit. I can understand your hesitancy to accept my characterization of procession, given how brief and incomplete it is. I recommend that you read Aquinas’ explanation of this topic. I accept and adopt his position on this matter.

Clearly there are two issues involved with the filioque: whether it is valid theology as well as whether it was validly inserted into the creed. But I don’t think the insertion is as clearly one-sided in favor of the East as you indicate.

For example, the Council of Constantinople in 381, which is the origin of today’s Creed, didn’t invite the Bishop of Rome (or any Western bishop, for that matter), so how can that be considered a truly “conciliar” decision? Augustine didn’t even know about the Council when he was writing thirty years later.

Also, the Council of Ephesus’ condemnation of any change of the Creed – which is often invoked by Eastern Christians in this context – was explicitly talking about the original Nicene Creed, which the Council of Constantinople already modified!

I don’t disagree that, in Eastern ecclesiology, the insertion of the filioque is problematic. But I do not think it was an egregious offense in light of the history as some Orthodox today make it out to be.

I would agree that as Catholics we cannot find the wholesale rejection of the filioque in Orthodox circles acceptable. But I do not agree that their rejection of it means that their own understanding is necessarily faulty (although I do think when they add the word “alone” after the Father that they are in fact outside of their own Tradition on this matter). But clearly just not having the filioque included in the Creed is acceptable, as that was the norm for centuries – the problem lies in rejecting the filioque as heretical.

Also, even as a Catholic I am uncomfortable with your language of Son as “co-principle”. To me, that makes it sound like the Son and the Father are equally the principle of the Spirit (which is exactly what the East rejects), but in the West we agree that the Father is “principle without principle” and the ultimate origin (not in time, of course) of the Trinity.

You did not read my comment sufficiently carefully; and your analogy of wall colors is not apropos. I did not say that the Greek formulation was, taken by itself, necessarily in error. I agree that the East’s formulation could be correct from the Eastern perspective, if, as I wrote above, it is understood in a certain way (i.e., that the procession of the Spirit begins with the Father in respect to dignity or priority (but not in respect to time or causality) but that the Son is, nonethless, also a co-principle of this procession). When the Greeks deny the Filioque, however, they deny that they have an acceptable understanding of their own formulation, since they necessarily deny that the Son is a co-princple by denying the Filioque. They show that they have a significantly different position, regardless of perspective and terminology; and a significant difference is all that is required to be in error in this matter. Truth and falsehood are never necessarily separated by a contradiction. A contradiction simply requires that one position must be incorrect.

The Greek reaction to the Latin position necessarily reflects upon its understanding of its own position, for both positions refer to the same reality. The two wall colors do ultimately belong to the same wall.

I applaud your “holding high” Peter Gilbert who is one extremely conscientious and painstaking scholar, and he has the scars to prove it.

I subscribe wholeheartedly to your reply to Ben, and would mention the following as hopefully an additional point.

The principle of contradiction says that two things cannot both be, and not be, in the same sense.

I believe that the West has focused on the Trinity primarily from the standpoint of Christ and His Nature, deriving knowledge about the Father and Son from Him, in an almost phenomenological way. The East, without neglecting Christology at all, have focused on the Trinity more or less on its own terms.

I think they both address facets of the jewel that is our Faith, but by contemplating different facets of an Infinite Mystery, whose “facets” are numberless.

I don’t think they are saying it is simply a misunderstanding of terminology. Congar specifically believes that the two sides come at the mystery from two different angles, thus seeing it differently. Put simply (and not entirely accurately, but hopefully usefully), the West starts with God’s one substance and from that proceeds to His three persons, while the East starts with the three hypostases and proceeds to the one ousia. These different viewpoints lead to alternate – but not necessarily contradictory – theologies.

For example, say that a wall is black on one side and white on the other. If you are standing on one side you will say, “the wall is black”. If you are standing on the other side, you will say “the wall is not black”. Both are correct, from their viewpoint. Of course, this analogy is limited, so we can’t take it too far. But it gives some idea of the issues involved.

I do think it problematic when the East says that the filioque is a heresy, period. Obviously, this is not acceptable. But I don’t think it is necessarily wrong to say that the filioque is unacceptable within the context of Eastern theology. In fact, I would say that the Catholic Church implicitly affirms that statement by the fact that they do not require the Eastern Catholic Churches to recite the filioque during their liturgies.