The phrase ‘partial’ or ‘imperfect communion’ has come into vogue in official Catholic discourse since Vatican II to refer to the relation which baptised non-Catholics have to the Church. It was put into Unitatis Redintegratio without being defined, as if it were an unproblematic phrase, being put forward there as the reason why the Catholic Church accepts such people as brothers (UR 3). The modern Catechism quotes this same passage of Vatican II, again without defining the phrase.

Obviously there is a sense in which baptised non-Catholics are closer to us than, say, Jews and Muslims. So St Augustine remarked that Catholics use the word fratres, brothers, of the Donatists, and not of the pagans. The problem is in the word ‘communion’. It suggests that the baptised non-Catholic as such has a share, albeit a lesser one, in the good things of the Church, in particular in the life of grace and the indwelling of the Holy Spirit. Now this can only be true when the non-Catholic in question is in good faith; if he is not, but is a formal heretic, he is to that extent in a worse position than the Jew or Muslim. It is probably a good idea in our dealings with a baptised non-Catholic to assume good faith, as an application of the principle that we should always interpret people’s behaviour in the best way possible. But are we to assume not just that some given baptised non-Catholic but that all such people are in good faith? How would that fit with the honour due to God, who has not hidden His church under a bushel? Yet it seems that some such assumption would have to be made if we are to make a blanket statement such as ‘Protestants are in partial communion with the Catholic Church’.

I suggest, then, that not the doctrine of Unitatis Redintegratio, but its vocabulary is unsatisfactory. Rather than ‘partial communion’ it might be better to say, ‘a baptismal relationship’.