René Descartes (31 March 1596 – 11 February 1650) philosopher and mathematician extraordinaire’s natural theology is worth reflecting on. Some have wanted to argue that Descartes’ methodological skepticism, where he doubted to the point where he thought he could doubt no further (cogito ergo sum), served as the basis for the modern turn-to-the-subject rationalism we experienced in the English Enlightenment and French Renaissance. But this can be contested, and has been. That notwithstanding what I want to briefly survey in this post is indeed Descartes’ natural theology. What is interesting to me about his style of natural theology was that he was attempting, in dualistic fashion, to on the one hand think as a Christian (when it came to his personal salvation), and on the other hand think as a critical philosopher as if he could think himself (critically so) to the base of all ‘being’ without reference to a Christian metaphysical framework; that he could achieve this purely as a rational exercise in philosophical reflection.
Étienne Gilson offers some excellent coverage on Descartes in this regard, so I wanted to share a snippet of that with you here. Gilson writes:
We are not beginning to see why, and in what sense, the metaphysics of Descartes was a decisive moment in the evolution of natural theology. Evolution, however, is not always synonymous with progress; and this time it was destined to be a regress. I am not arguing here on the dogmatic assumption that the God of Saint Thomas is the true God. What I am trying to make clear is the objective fact that, even as a philosophical supreme cause, the God of Descartes was a stillborn God. He could not possibly live because, as Descartes had conceived him, he was the God of Christianity reduced to the condition of philosophical principle, in short, an infelicitous hybrid of religious faith and of rational thought. The most striking characteristic of such a God was that his creative function had integrally absorbed his essence. Hence, the name that was hereafter going to be his truest name: no longer “He who is” but rather “The Author of Nature.” Assuredly, the God of Christianity had always been the Author of Nature, but he had always been infinitely more than that, whereas, after Descartes, he was destined progressively to become nothing else than that. Descartes himself was too good a Christian to consider Nature as a particular god; but, strangely enough, it never occurred to him that to reduce the Christian God himself to no more than the supreme cause of Nature was to do identically the same thing. Metaphysical conclusions so necessarily follow from their principles that Descartes himself reached at once what were to be the ultimate conclusions of his eighteenth-century disciples when wrote the following sentence: “By Nature, considered in general, I am now understanding nothing else than either God, or the order and the disposition established by God in created things.”
We know Baruch Spinoza, a contemporary of Descartes, went further with Descartes’ project and radicalized to the point that indeed for Spinoza a pantheist conclusion would be arrived at on some of the very premises produced by Descartes’ own thought processes.
Whether or not Descartes ought to be implicated in the modern-turn, to one degree or another, what is rather clear (at least to me) is that his ‘naturalism’ coheres well some of the later rationalisms that would indeed develop. What these things highlight for me once again is that attempting to think God based purely upon natural/rationalist reflection does not produce the God revealed in Jesus Christ. Some might argue (and do) that inherent to fallen nature there remains a residue of God waiting to be discovered and plundered for the purposes of providing details about who God is (categorically) in such a way that the Revelation of Godself can be pollinated for the edification of the Church and Christians.
But I constantly ask: why? Why as Christians, those who know the voice of our Shepherd, indeed those who are only paying attention to his voice because we have his Spirit, do we need to rely upon the philosophers (of any age) to fill in the gaps or provide the bedrock foundations (like immutability, infinity, omnipotence, etc.) for the Christian to genuinely articulate a theological grammar for explicating who God is? Descartes provides an excellent example of someone who made this attempt, and failed.
What differentiates Descartes from Aristotle? One thing is that Descartes actually had a Christian theological grammar in place as a Christian even before he charted out to think first principles as a philosopher; and even still he ended up thinking a god from negative reflection upon creation. Aristotle didn’t have the advantage of Descartes, maybe some would say this actually was an advantage for Aristotle; in the sense that his discursivity was of a more pure type; that his reflections were actually taking formation in a genuine process of discovery, in regard to arriving at actual infinity and pure being. Either way, and once again, why the need to trek this path? The response from the proponents is: because the ecclesial tradition walked this path, that the church developed these patterns of theological grammar, this sacra doctrina by appealing to figures like Plato, Aristotle, et al. But this itself is an appeal to a ‘natural theology,’ it’s an appeal to reading God’s providence off of the face of the history of church doctrinal development; as if: just because patterns of “orthodox” doctrine have developed in certain lines of trajectory, and have come to dominate the “mind of the church,” that this must be God’s stamp of approval on the ‘way’ that the orthodox doctrine has indeed developed.
But to appeal to church tradition and its development as if God has thus so seen to this in a providential way is only to presume upon the very premise under contest: i.e. natural theology. Why should we commit ourselves to a circle of reasoning like this? It’s as if God’s Self-revelation in Jesus Christ is not enough; that it does not provide a robust enough explication and exegesis of who God is for his church. What if God were to want to correct certain trajectories in his church; even big trajectories that we call tradition? I mean are there even means to challenge certain trends or trajectories (such as natural theology) in the Church, in the sacra doctrina?
I’m pretty sure the Reformed think so. And yet what counts as the dominant voice in Reformed theology (i.e. the aspect of Reformed theology that is being retrieved) affirms natural theology (not all, but many). Indeed, the movement in Reformed theology, think of Mike Allen and Scott Swain as two young and prominent voices, are constantly arguing for and appealing to a catholic Reformed faith; a faith that is fully contingent upon a common cored commitment to and affirmation of the tradition of the church (particularly as that entails theology proper and Christology and its attending loci). But what if the tradition has component parts in it that undercut the possibility for its own regulation and even contradiction? In other words, what if commitment to natural theology (and an analogia entis as a subset) itself quenches the possibility for self-reformation and re-trajectorizing even within the solid boundaries set by the so called ecumenical creeds? How does a genuine theology of the Word have space to do its reformative work (semper reformanda) at a theological ontological/epistemological level if a prior commitment to a natural theology as a prius is allowed to say what a genuine knowledge of the living God looks like or not; and this prior to meeting God in the New Covenant of his blood in Jesus Christ? What happens when natural theology is the baptizer of Jesus; what kind of Jesus do we encounter in these waters; and as such, what kind of God do we come into union with if natural theology is his preamble to the world rather than the risen Christ?
 Étienne Gilson, God And Philosophy (New Haven: Yale University Press, 1955), 88-90.