Since I am scheduled to present on this topic for one of my classes at UD, I thought that I would revisit Marion’s take on St. Thomas as reflected in his article, “Thomas Aquinas and Onto-theo-logy.”
In this article, Marion retracts a good deal of his former criticism of St. Thomas as found in God Without Being. Specifically, he withdraws his former claims that Aquinas’ naming God ipsum esse¬ makes an idol out of being, and that Aquinas is guilty of onto-theo-logy. So what is meant by onto-theo-logy? According to Heidegger onto-theo-logy characterizes the Western metaphysical tradition and is expressed as an attempt by philosophy to use conceptual systems in order to control and master Being (as well as God). Marion is sympathetic to Heidegger’s critique, yet he sees Heidegger making an idol out of Being. For the purposes of this article, Marion highlights three foundations at work in onto-theo-logy.
First, there is the Gründung, i.e., “the conceptual foundation of entity as such by being.” Whatever serves as the conceptual foundation—be it “God” or whatever—must be inscribed within the domain of metaphysics. That is, it itself must become thinkable as an entity (or according to a [univocal] concept of entity). To illustrate his point, Marion turns to one of the ways (there are other ways as well) in which Descartes exemplifies this Gründung. In Descartes, being is defined on the basis of thought. Consequently, being grounds entities conceptually, “to be is to think or to be thought” (esse est cogitari aut cogitare). All entities, including the “first” or “highest” rely on this foundation through being (p. 41), and all entities including the “highest” or “first” are thought according to a (univocal) concept of being. In sum, the first characteristic of onto-theo-logy amounts to inscribing God (as subject or object) within the domain of metaphysics and making God subject to a univocal concept of being.
Second, we have the Begründung. That is, “the foundation of entities by the supreme entity according to efficient causality.” Here we have a reciprocal grounding between the “first entity” and all other entities. That is, there is a reciprocal grounding between whatever serves as the “first entity” (e.g., Pure Act) and all other beings, and this grounding reciprocally perfects/establishes both the first entity and all other entities. E.g., according to Aristotle, beings “are” to the extent that they are in act. The “Unmoved mover” of Aristotle’s system is of course “Pure Act.” Here we find a kind of mutual “grounding” principle. That is, the Unmoved mover is not only the final cause toward which all beings move, but is established in a preeminent way by the (same) principle by which beings “are,” viz., by the principle of actuality (“to be is to be in act”). This principle founds the Unmoved mover as highest being, that is, as Pure Act, just as it establishes all other beings in so far as they are. Or returning to Marion’s Cartesian example, the ego as preeminent being thinks itself as res cogitans and therefore grounds its own existence. Likewise, it also “grounds in reason” the other entities “which are, only insofar as they are thought by it” (pp. 42-43). In sum, the “God” (or highest being) functions as the (efficient) causal foundation for all entities. This founding relationship is reciprocal, i.e., the “God” grounds beings and beings ground/establish God.
Third, there is the self-grounding of the ground or the causa sui. That is, “the foundation of the conceptual foundation by the efficient foundation” (p. 42). The preeminent being is defined by its function as causa sui. Here you have a supreme being that “grounds by grounding itself through itself” (p. 42). In other words, the conceptual foundation is grounded in the (efficient) causal foundation, which in the case of our Cartesian example is the ego or res cogitans. In sum, the “God” founds itself, just as it founds all other beings.
In the next post, we shall see how (according to Marion) Thomas escapes all three characteristics of onto-theo-logy.
 As found in in Mystics: Presence and Aporia eds Michael Kessler and Christian Sheppard, (Chicago: Univ. of Chicago, 2003), pp. 38-74.