The widely accepted Grundaxiom of Karl Rahner's doctrine of the Trinity, "The
economic Trinity is the immanent Trinity and vice versa," functions in contemporary
theology as a means of reconciling the seemingly contradictory claims: (a) that God
has revealed the doctrine of the Trinity to the church; and (b) that he has not
disclosed this doctrine verbally in Scripture. Rahner's Grundaxiom, that is to say,
serves to legitimate theological reflection on the Trinity that does not presuppose a
pre-Enlightenment understanding of Scriptural revelation.
In our dissertation, however, we argue: (a) that Rahner's Grundaxiom does not
cohere with certain elements of Rahner's own theology; (b) that the Grundaxiom
entails conclusions inconsistent with what Rahner regards as Trinitarian orthodoxy;
and (c) that a pre-Enlightenment understanding of Scripture, by contrast, constitutes
a reasonable foundation for Rahner's ideal of Trinitarian orthodoxy. We conclude,
therefore (d) that, barring the possibility of some third foundation for the theology of
the Trinity, Rahner's doctrine of the Trinity itself presupposes a pre-Enlightenment
conception of Scriptural revelation.