McCall opens his book on the Trinity, as any good analytic theologian might do; by setting up the dialogical landscape (or lack thereof) that has inhered (or not) between constructive/dialectic theologians (which is where I am coming from), and McCall's camp, the analytic/philosophic theologians. He introduces his book this way to be clear about one of his intentions for writing this book, and for writing it in the way he does; one of the reasons he is writing this book is to bridge the chasm that is in place between the constructive/dialectic theologian and the analytic. With this context understood, let me quote some of the sentiment that McCall thinks would be good for Systematic Theology in general (it is something that repels me, just to give you a heads up):
[...] The theologians need --- sometimes desperately need --- the kind of assistance that might be found in the analytic toolkit. The theologian R. R. Reno sees this clearly, and he sounds a clarion call for theologians to employ the conceptual tools offered by the analytic tradition. As he sees things, analytic methodology bears a close resemblance to scholasticism, and he thinks contemporary theology could use a good does of it. He says that although the "overwhelming majority of theologians today sift through Heideggar and his philosophical children and grandchildren to try and find useable material," this impulse is fundamentally "misguided." Reno concludes that analytic philosophy might be an important ally for theology, and this is "because analytic philosophy is unequivocally and fundamentally a force for the strengthening of truth, not its weakening. [emphasis mine] [Thomas H. McCall, Which Trinity? Whose Monotheism?, 4-5]
Without wanting to be too foreboding, and wanting to give McCall a fair reading; let me just assert up front that exactly what contemporary theology does not need is a good dose of scholasticism! If what Tom means by this is that contemporary theology needs to constructively retrieve the substance metaphysics that classical theism hath bequeathed to us in Christian Theology through the seminal kind of work in this direction provided by the Thomist synthesis with Aristotelian categories and Christian Theology; then I object! I think this is what Reno means, and thus what McCall thinks is clarion.
What we need is an onto-relational metaphysic (or some such nomenclature) that emphasizes a Trinitarian theology that is given shape by an understanding of a personal God who has his being as a Subject-in-Being distinctiveness. In other words, we don't need to work from philosophical categories, like substance metaphysics offers up, that primarily think of God through monadic (unitary) categories. It is this ground that Federal Calvinism (amongst other developments within the Christian theological tradition) has developed; which has given us a God who must relate to his creation through impersonal decrees and Law-like precision.
So, four and five pages in; I object, Tom McCall! We'll see where you lead me ...
