Murphy’s work also touches on the grace/nature, reason/faith debate. The way she construes it, Gilson’s notion of ‘Christian philosophy’ lies in a “third domain”, as von Balthasar terms it. This “third domain” lies somewhere between philosophy and theology, it is neither ‘purely natural’ nor entirely theological. Thus the arguments for God’s existence are not pure philosophical arguments as has often been argued and which many contemporary theologians such as John Milbank take objection to. But neither are they merely ‘probabilistic’ arguments designed primarily for believers to give them a reasonable account of their belief in God, nor do they depend on an original intuition that God exists as Milbank would have it. As Murphy puts it: “A Christian philosopher is neither solely a Christian (‘graced’) nor solely a natural philosopher: she is standing on the ground which she knows to be grace and her interlocutor may not.” Thus the fact that nature is always and everywhere ‘graced’ (as de Lubac argues) does not preclude the possibility of engaging nonbelievers in debate and arguing for God’s existence in terms that do not immediately appeal to the supernatural.
The Spanish philosopher Xavier Zubiri is also brought in here to buttress this point. He claims that human beings are always ‘religated’, which signifies “a religious placement, provoking an awareness of the awkwardness of the human position within the cosmos.” (202). Zubiri made the case for a religious priority over secularity and the ‘religated’ sense of humanity’s existence as the catalyst for the growth of the sciences, including mathematics, grammar, anatomy and so on. It is because of humanity’s religious dimension, that these sciences have de facto arisen in history. Analogously, the proofs for God’s existence arise because of humanity’s ‘religation’ but they do not depend on a supernatural starting point for their validity. Non-believers may not know they stand on ‘graced ground’, but this does not mean we need to insist to them that this is the case; to do so would be manifestly self-defeating. There is no reason why Milbank should insist on the proofs not being demonstrative on the grounds of our graced nature. They can still be offered to nonbelievers who do not know that they stand on ground which is ‘already graced’. As Murphy puts it “Milbank seems to divest the natural desire for heaven of its great humanistic potency when he wields it against discursive argument for God’s existence.” (204) Hence de Lubac’s assertion of a ‘natural desire’ for the supernatural ought to retain it’s full paradoxical nature and not be construed as ruling out ‘natural’, discursive arguments for God’s existence. They may only arise because man is graced and tends towards the supernatural, but this does not thereby render them ‘unnatural’ and unfit for use as arguments with which to engage those who remain oblivious to the ubiquity of grace in our world.