The logic of God: Why metaphysical proofs still matter
The cosmos cannot be the source of its own existence. The cosmos is not a necessary being. In this regard, David Hart rightly remarks that “the contingent can only exist derivatively, receiving its existence from the Absolute.”
When Stephen Hawking and Leonard Mlodinow claim that God’s existence is no longer plausible because all things could have come forth from the quantum law of gravity, they fail to recognize, as Hart says, that the issue is “the very possibility of existence as such, not only of this universe but of all the laws and physical conditions that produced it.” It is not necessary that any finite thing, let alone a quantum law, exist. Finite things exist, but they are merely limited modes of being; they are not being as such. A quantum law, insofar as it is, must derive its being from a source.
Hawking and Mlodinow can be excused for their failure to grasp that the issue is “existence as such.” Their misunderstanding is shared by many professional philosophers. In Arguing about Gods, Graham Oppy supposes himself to be undermining Thomas Aquinas’s five ways of demonstrating God’s existence when he remarks that “it is hard to see that there is anything in Big Bang cosmology that rules out the existence of an infinite regress of changers, each changed by another.” Oppy’s point would not have bothered Aquinas at all, since Aquinas allows philosophically for an eternal universe. In fact, none of Aquinas’s five ways depends on the universe having a temporal beginning.
All too often, questions regarding “existence as such” are naively dismissed by supposing that “the physical universe is merely a brute fact” (see David Fergusson’s Creation). Finite existence, far from being a self-sufficient “brute fact,” requires explanation, since finite existence is not existence per se.
When classical Christian thinkers such as Aquinas offered philosophical demonstrations of God’s existence, did they think of them as proofs—that is, as rational arguments that strictly demonstrate that God exists? Rightly anxious to dissociate Aquinas from Cartesian or empiricist notions of “proof,” some contemporary scholars deny that he intended his five ways to be rigorous demonstrations of God’s existence. For example, in his generally excellent book responding to the new atheism, Faith and Its Critics, Fergusson remarks that Aquinas’s five ways “are less exercises in demonstration of God’s existence than a directing of the human intellect towards a mysterious limit of thought that in the Summa Theologiæ can only be further illumined by divine revelation.” Similarly, Stanley Hauerwas suggests that Aquinas’s five ways merely seek to “‘prove’ that language/reason may find itself to be insufficient to testify to the God who is the beginning and end of all that is.” Hauerwas emphasizes that “the God we worship and the world God created cannot be truthfully known without the cross.”
However, this effort to avoid the term proof is mistaken, both as a reading of Aquinas and as a broader claim. Certainly, language and reason are radically insufficient when it comes to God, since God, who is transcendent and infinite, is in an obvious sense not comprehensible by finite minds. We cannot form a concept of what God is because God, to say the least, cannot be circumscribed by a finite concept. Nor can the living God whom Christians worship be fully or adequately known without Jesus’ cross or without the ecclesial communion established by Jesus. In this regard, Roger Scruton is surely right that the God of the proofs, if the proofs were all we had, would be too impersonal.
Yet, for good reason, Aquinas does not eschew the word prove—though his proofs are metaphysical, not empiricist or Cartesian. The word prove reminds us that we are not here dealing with an experiential intuition, a gesture toward infinite mystery, or an opinion based on personal sensibility. In the Summa Theologiæ, Aquinas states, “The existence of God can be proved [probari] in five ways.” After explaining what constitutes a rationally probative demonstration from effect to cause, he observes that “the existence of God . . . can be demonstrated [demonstrari] from those of his effects which are known to us” and adds that the existence of God “can be known by natural reason,” even though “there is nothing to prevent a man, who cannot grasp a proof [demonstrationem], accepting, as a matter of faith, something which in itself is capable of being scientifically known and demonstrated.”
In making this claim about the ability of human reason to demonstrate conclusively that God exists, Aquinas is hardly alone. Rooted in such biblical passages as Wisdom 13 and Romans 1, his position is shared not only by his contemporaries and medieval predecessors but also by the leading Greek and Latin fathers of the church. Indeed, Ian Markham is quite right to insist, “From St. Paul in Romans 1, through to St. Augustine and St. Thomas, we find natural theology central. The Barthian and postmodern lack of interest in this way of thinking is a significant departure and, I would add, betrayal of the Christian tradition.”
Not only in popular science but also in contemporary humanities God is too often imagined as something like the Great Pumpkin, beyond rational discourse. For example, in Cultivating Humanity: A Classical Defense of Reform in Liberal Education, Martha Nussbaum appreciatively discusses the University of Notre Dame’s efforts to construct “a distinctively religious campus that is also a place of genuine inquiry and debate.” But her discussion of how to renew the “cultivation of humanity” in modern universities—how to nourish students’ “ability to think critically, to examine themselves, and to respect the humanity and diversity of others”—all too predictably never mentions the need for university professors and students to discuss the topic of God’s existence. Surely, however, the question of whether there is a God will be integral to answering what humanity is and what human cultivation and critical thinking involves.
Brad Kallenberg points out that the philosopher Ludwig Wittgenstein provides a reason for doubting that the demonstrations of God’s existence can make sense within a secular framework. Kallenberg summarizes Wittgenstein’s concern: “How do I know that two people mean the same when each says he believes in God? Practice gives the words their sense.” In other words, when we hear someone express belief in “God,” we do not know what kind of “God” (or “god”) is at issue. For Kallenberg, it is a mistake to suppose that “arguments about God’s existence require no special attending behaviors to get their point.” Such “special attending behaviors” include “the practice of prayer or praise.”
I agree that whether or not we pray may make a difference in how we respond intellectually to the demonstrations of God’s existence. But the reasoning of the various demonstrations—like that of the various critiques of these demonstrations—is open to being assessed by Christian and non- Christian, theist and nontheist. They do not depend for their logic on faith or prayer.
Appreciatively summarizing Aquinas’s view, which I share, John Haldane states that “even those who do not already have an idea of God are in a position to determine that God exists simply by reflecting on the natural order”—even if such rational reflection is profoundly aided by grace and thus by prayer.
Given the importance of reasoning about God, the notion that God means solely what individuals experience it to mean—a notion that is widespread in popular spirituality today—must be rejected. Deepak Chopra claims that “‘God’ is an empty term except as it finds expression through the revelations of all the saints, prophets, and mystics of history.” If Chopra had argued simply that we need to pay attention to the saints, prophets, and mystics rather than solely to philosophers (or to theologians, for that matter), then his point would be well taken. Pascal and Newman likewise make clear that demonstrative reasoning is secondary for real human connection to God. But to say that “‘God’ is an empty term” except as experienced in divine revelations is mistaken, since God has a meaning available to reason rather than solely being available to private religious experience.
Not surprisingly, the seeming refutation of the demonstrations has caused serious problems for Christianity in the West. As Fergus Kerr has pointed out, “A main reason for the decline of churchgoing in Western Europe . . . is that people take it for granted that no such proofs are available.” For such people, belief in God is utterly irrational, a by-product of the naive simplicity of previous evolutionary stages. Roger Scruton comments that a growing number of people in the West imagine that belief in God is “a sign of emotional and intellectual immaturity.”
Julian Baggini’s work exemplifies this position. For Baggini, “belief in the supernatural is belief in what there is a lack of strong evidence to believe in.” He proposes that the acceptance of little or no evidence for a belief is what primarily differentiates believers in God from atheists. In his view, therefore, believers in God are such because they accept beliefs “that lack or are contrary to evidence, experience, or logic”: “Religious belief postulates the existence of entities which we have no good evidence to believe exist.”
Baggini points to two biblical stories about faith: Abraham’s near sacrifice of Isaac (Gen. 22) and doubting Thomas (John 20). The assumption here is that these biblical stories, shorn from their context, display believers’ commitment to irrationality in their relationship with God. Baggini imagines that he has shown that “it is disingenuous for believers to put forward arguments to support their beliefs.”
On the contrary, the knowledge that God exists is still available to all who are willing to consider what Scruton calls “the topic of contingent being” and the puzzle of “being qua being.” And as David Hart emphasizes, the true irrationality is on the side of unbelief, since it turns existence and consciousness into a surd: “It makes sense to believe in both reason and God, and it may make a kind of nonsensical sense to believe in neither, but it is ultimately contradictory to believe in one but not the other.”
Rigorously thinking through the logical consequences of his atheism, Alex Rosenberg admits that “the ‘thoughts’ in the brain can’t be about anything at all, either things inside or outside the brain. The brain doesn’t store information that way. Rather, it stores information about the world in vast sets of input/output circuits that respond appropriately to one another and to their environment.” Of course, Rosenberg is convinced that he knows quite a good deal about reality—even though his “thoughts” are no more than neural circuitry. He remarks, for example, “There is no reason to doubt atheism. What we know about physical and biological science makes the existence of God less probable than the existence of Santa Claus. And the parts of physics that rule out God are not themselves open to much doubt. There is no chance that they will be revised by anything yet to be discovered.”
This is sheer nonsense, since there is no “physical and biological science” that could ever even possibly “rule out God.” God is the infinite source of physical and biological things, but God is neither embodied nor detectable in any way by the empirical methods of scientific inquiry. Rosenberg’s remark that “parts of physics . . . rule out God” shows how widespread metaphysical ignorance has become.
The seeds for this crop of ignorance were planted long ago. As John Courtney Murray noted in 1964, “the fixed philosophical attitude today is to say that a natural theology is impossible, that it is impossible for human reason, beginning only with the data of experience, to construct a valid doctrine of God.” And there is nothing particularly new in this philosophical attitude; modern sophistry has its ancient predecessors. The biblical book of the Wisdom of Solomon describes the sad quandary experienced by persons who believed that “we were born by mere chance, and hereafter we shall be as though we had never been; because the breath in our nostrils is smoke, and reason is a spark kindled by the beating of our hearts. When it is extinguished, the body will turn to ashes, and the spirit will dissolve like empty air” (Wis. 2:2–3).
Reflecting on modern skepticism, Murray complains that despite its claim to be more rational than belief in God, skepticism “calls an arbitrary halt to the movement of the mind.” This it certainly does, not least by refusing to confront seriously the puzzle of “being qua being.”
As a Christian believer, Murray adds a further observation: “How odd of God it would have been had he made man reasonable so that, by being reasonable, man would become godless.” How odd indeed, and as Murray recognizes, God did no such thing.
This article is adapted from Matthew Levering's book Proofs of God: Classical Arguments from Tertullian to Barth, just published by Baker Academic, a division of Baker Publishing Group. © 2016. Used by permission.