In my recent paper on the Trinity (discussed by Dale and I here and here) I distinguish two ways a thing can meet sufficient conditions of personhood. One way is to behave, function, or perform in such a way as to meet those conditions. So if a robot or group, for example, became morally responsible or rational in virtue of function alone, it would thereby become a person—a functional person. The other way is just to have the right kind of intrinsic nature. Regardless of function, you, me, fetuses, and comatose patients are persons in virtue of our intrinsic natures. We are intrinsicist persons. I made use of this distinction to defend a variety of Social Trinitarianism: The Father, Son, and Spirit are intrinsicist persons, whereas the group they constitute is a functional person. But the distinction admits of other new varieties of Trinitarianism as well. Here are two:
1. Semi-Social variant: The Father and Son are intrinsicist persons, whereas the Spirit is a functional person (this variant was first suggested to me by Todd Jefferson). I say this is a “semi-Social” variant because Social Trinitarianism is ordinarily understood to be the view that all three divine persons are what I’m calling intrinsicist persons. But on this variant, the Holy Spirit is not that kind of person. Interestingly, this variant might well be suggestive to those who think the Biblical data are less than clear about the Spirit’s “full” personhood (i.e., intrinsicist personhood) as compared to the Father and Son. Maybe we can interpret this as meaning the Father and Son are clearly intrinsicist persons, whereas if the Spirit is a person at all, the Spirit would be a person in a different sense. The Spirit is rather dynamic, often identified primarily with the performance of specific functions (convicting, sanctifying, inspiring). But the Spirit is also praised and prayed to, affording treatment as a person. We might then have an intrinsicist Binity of Father and Son with the Spirit as the bond between them, a bond dynamic enough so as to functionally meet conditions of personhood on its own.
2. Non-Social variant: In his paper “Simplicity or Priority,” Gregory Fowler floats the following view: The Father, Son, and Spirit are persons who depend on and are “functional parts” of the one God who is also a person. He defines a “functional part” as “a proper part of a living thing such that being the sort of proper part it is involves performing a certain function in a living thing.” [in Kvanvig (ed.), Oxford Studies in Philosophy of Religion Vol. 6, p. 127]. A heart, for example, would be a functional part of you. Fowler does not say how such a view would avoid the Quaternity worry, but the distinction between intrinsicist persons and functional persons provides a ready way: God would be one intrinsicist person that grounds three functional persons, the Father, Son, and Spirit. The first functional part could be that part of God whose function corresponds to the economic activities associated with the Father, the second with those associated with the Son, and third with those of the Spirit. Each functional part, having its own unique function in the life of God and in the lives of God’s people, would qualify as distinct functional persons.
I am not here considering what objections there might be to these variants of Trinitarianism. But it does seem that the distinction between intrinsicist and functional persons can be fruitfully applied to the doctrine of the Trinity in more ways than one. So one prize of having functional persons is having more theories of the Trinity to work out!