Let me just pull this quote out of the broader context from which it is taken in order to preserve this definition in online form for future reference; if for no one else but me (and keep reading, because at the end of the quote I go off on a tangent in regard to Steve Holmes’ recent book on the Trinity and Thomas Torrance’s following definition of ‘onto-relational’). This definition is so important to understand in regard to grasping Thomas Torrance’s theological project that it is hard to overemphasize it. If Torrance has a metaphysic (which I think he does), then this is it in brief. The following quote from Torrance comes from within a broader context where he is discussing Clerk Maxwell’s approach to science. Torrance argues that Maxwell’s approach comes from a Patristic based conception of relationality and persons-in-relation against the mechanical paradigm of things that dominated the universities and sciences during Maxwell’s era (and we could say still does in many sectors of the sciences: Just think of someone like Richard Dawkins). While Torrance is describing Clerk Maxwell’s approach he provides a definition for what became quite definitive for himself; what became definitive at a metaphysical and even physical level for Torrance was what he called onto-relations. Here is how TF Torrance defines what onto-relations entail:
… It will be sufficient to recall that it was due to the development of relational thinking about the activity of God in creation and incarnation that enabled Christian theology to overcome the static container notion of space, and it was out of this relational thinking that there came the concept of person, unknown in the world before Christianity, in accordance with which it was held that the relations between persons are of constitutive importance for they enter into what persons really are as persons. Thus an onto-relational way of understanding persons in community rejected an atomistic way of thinking of them as self-sufficient, independent, separated individuals who may be organised into a society only through their external relations with one another–the very notion into which John Locke disastrously carried European socio-political thought under the impact of Newtonian atomism and action at a distance….
Recently I read Steve Holmes’ book on the Trinity, in that book he critiques Barth and Dorner, in particular, of introducing an existentialist understanding of person into Trinitarian theology. He argued that the result of this had nothing to do with the way ‘person’ was conceived of for the Patristic framers of ecumenical Trinitarian theology. Whether or not I fully agree with Holmes on this point (which I don’t fully), what would have been of great benefit, would have been if Holmes attempted to engage with Thomas Torrance as an interlocutor on the conception of ‘person’; to engage with TF Torrance’s onto-relational understanding of relationship not only between the Divine Monarxia, but subsequently at an theological anthropological level. I think Torrance offers something from a modern theological landscape, retrieved somewhat from the Patristic period, that would challenge the idea that modern theology should be totally junked in regard to a Trinitarian theology. Torrance stands out as someone, with his category of ‘onto-relational’, that indicates that the modern project has not been a complete waste when it comes to articulating afresh categories for thinking Trinitarian theology.
And we could and should argue that Torrance’s proposal is modern insofar as it draws directly off of the work of Einstein and Clerk Maxwell (among other moderns). The unique thing with Torrance is that he hagiographically ties these modern concepts back into the Patristic paradigm more stridently than someone like Barth does. Nevertheless, Torrance is still largely a modern theologian who seeks to be one in ressourcement.
 Thomas F. Torrance, Christian Theology & Scientific Culture (Belfast: Christian Journals Limited, 1980), 50.