Analytic philosophical theology on the Trinity has focused primarily on the “logical” problem of the Trinity, the problem of how the Father, the Son, and the Holy Spirit—construed as three really existing, really distinct divine entities—can also be exactly one God (Cartwright 1987). The Church’s first two ecumenical councils defined the orthodox terminology now used to state the doctrine, but the councils did not attempt a philosophical solution to the logical problem. In the traditional terminology, the Father, Son, and Spirit are three distinct divine persons (personae in Latin; hypostases in Greek) who share a single divine nature (substantia in Latin; ousia in Greek; see Tanner 1990: 5, 24, 28). The logical problem then becomes the problem of how three divine persons (whatever we mean by “persons”) can instantiate a single divine nature (whatever we mean by “nature”) while remaining numerically distinct.