Kathyrn Tanner is a well-known theologian and author. While some of her work focuses on theological support for certain political views, she has also written Jesus Humanity, and the Trinity: A Brief Systematic Theology.
To a philosopher’s eyes, this book is typical of much of the current theological literature. There’s not much argumentation for her views or against others’, nor is there any effort to justify belief in the doctrine, or much effort to adjudicate incompatible interpretations of it. The only task, on this way of thinking, is to properly appreciate it, and to draw out its wonderful implications for all of theology, as well as for practical life, individual and social. The ancient tradition is mined for all its lingo and metaphors. Tanner writes with brevity, and with a minimum of jargon, although she also has the theologian’s love for abstract nouns and passive constructions.
Is she a modalist? Yes, pretty clearly so, specifically, an eternally concurrent noumenal FSH modalist. To her credit, she stands up and says pretty clearly and concisely what others only think, or assert and then withdraw. In her own words,
Unity of essence or substance means that the three Persons of the Trinity are the very same thing or concrete substance in three modes or forms of presentation. They are like three distinct appearances of the same thing from different angles, although here such appearances are objective and lasting, unlike the transient effects of perspective, and although here the whole is presented differently and not just one side or part becoming visible from a particular point of view. The very same thing is therefore found repeated in Father, Son, and Holy Spirit, although none of these Persons is to be identified with any other: the Father is all that the Son is except the Son is not the Father, etc.
The three therefore co-inhere, they are in one another, in virtue of this same essence or substance reappearing in them in different modes of existence. (pp. 38-9)
… All at once this community of action is the life of the triune God. … here, in virtue of their identity of substance or essence, the will to work – in its exercise, particular shape, and general capabilities – is the very same among the three. (p. 40)
She also adds a twist that I haven’t seen before (which doesn’t mean it hasn’t been said before – I don’t know) – modes of modes! The humanity of Christ is a mode of the Son which is a mode of God.
The human existence of Jesus is, then, the very mode of existence of the Son (and not some distinct one). Thereby Jesus enjoys the same relations with the Father and Spirit as the second Person of the Trinity does. (p. 47)
She’s no Sabellian, then, as she holds that the three modes are coeternal. And she’s not liable to the charge, often levelled against “modalists”, that she makes the threeness in God an illusion. No – her modes are essential to God’s nature, to God “in himself”. But, she’s most definitely a modalist, as I define it. (Also note this clarification.)
A pretty positive review of the book, which gives a more complete idea of its contents, is here. Strangely, her modalism goes over the reviewer’s head; he refers to it as her “focus” on “God’s oneness”.
I’ve already said why I think Son modalism (hence, any FSH modalism) is false, and have ponied up some dire theological and practical consequences of Son modalism.
As far as I know, no theologians have protested or argued against Tanner’s modalism. Why not? Because she’s very much in the mainstream on this topic. As far as I can see, the main difference between her metaphysics of the Trinity and most others in the Latin or mainstream tradition is that she doesn’t shy away from the word “mode”.