Quantum Physics and Theology

While the details of quantum theory and Christian theology play a crucial role in Polkinghorne’s argument, his real interest in this book lies not in critically aligning the substantive claims of either realm—a task he has taken up in previous writings—but in comparing the various ways in which the substantive claims of each have been motivated, generated, and critiqued. Polkinghorne’s focus, in other words, is not so much on what science and theology know but on how they come to know it. One might guess that the motivating instinct behind his approach lies near to the idea that similarities of form can stand, more firmly than connections of substance, on the ever-changing terrain of scientific knowledge.

Polkinghorne groups his 14 vignettes into three categories: heuristics, history, and concepts (chapters 2, 3, and 4). According to the basic formula by which each vignette is structured—unfortunately, the book’s three central chapters are rather formulaic—each particular feature of rational inquiry is illustrated, first with an example drawn from physics and then with an analogous example drawn from theology.

In chapter 2 Polkinghorne identifies similarities in the heuristic strategies of scientists and theologians in terms of their techniques of discovery and questioning, as well as the importance to both groups of novel experiences and critical events. He notes, for example, that the interplay of theoretical creativity and experimental constraint in science, such as one finds in Einstein’s development of his relativistic theory of gravity (i.e., general relativity), is infinitely more complex than Bacon’s early account of “accumulating and sifting” evidence for the sake of finding useful generalizations. When Einstein wrote down the equations of general relativity in 1915, he did so not after sifting through reams and reams of data but only after “years of brooding on the nature of gravity”—though the theory was subsequently confirmed in a number of empirical tests. Christological thinking, says Polkinghorne, has likewise developed in the give-and-take of experiential challenge “from below” and theoretical conceptual exploration “from above,” yielding a complex conceptual framework rooted not merely in fideistic assertion but in experientially motivated belief.

The other analogies in chapter 2 are less compelling. After noting, for example, that scientists need to learn how to ask the “right” questions, Polkinghorne insists that theologians, in their turn, need to be clear about which questions will have answers that “control adequate theological thinking in the quest to find an acceptable interpretation of the Church’s knowledge and experience of Jesus Christ.” “Acceptable” as the theological analogue of “right”? In the scientific context, asking the right questions means posing problems that are tractable, ones that afford some demonstrable purchase on the truths of the natural world. In the theological context, at least according to Polkinghorne, accept-able questions are those which confirm and clarify what the Church has previously experienced and come to believe. This way of construing what the right theological questions are appears to leave little room for submitting the Church’s proclamation to theology’s own analysis of where the actual truth of the matter lies, let alone for the conflicting views of truth that have di-vided actual denominations and individual churches across the ages.

In chapter 3 Polkinghorne steps more surefootedly through a number of interesting historical parallels. He sketches similarities that touch on the growth of conceptual understanding over time, the need for interrelated concepts to do justice to the richness of experience, the influence of the tides of fashion, the importance of genius, and the inevitability of living with unresolved problems. One of the more substantial sections of this chapter recounts the development of s-matrix theory (“s” for “scattering”) in the 1950s and 1960s, which was initially regarded by many as a way out of the mathematical conundrums associated with the then dominant “field theory” approach to quantum physics. The s-matrix approach appeared to allow physicists to set aside the complexities of field theory in favor of a leaner approach that simply linked “before” and “after” states of quantum events. Eventually, however, s-matrix theory became so complicated that it, too, was abandoned, even as other developments led to a revival of the field theory approach. Polkinghorne connects the fortunes of s-matrix theory to theology by masterfully summarizing (in less than five pages!) the fluctuating emphasis placed on the historical figure of Jesus of Nazareth in the history of modern christological thought. In Polkinghorne’s revisionist account, Rudolf Bultmann becomes an s-matrix theologian who lamentably viewed historical detail as irrelevant to christological reflection. But just  as quantum physicists have returned to field theory after the collapse of s-matrix theory, theologians after Bultmann have returned to the question of the historical Jesus. So go the tides of quantum and christological fashion.

In chapter 4 Polkinghorne moves to the conceptual level, exploring similarities across science and theology in terms of the emergence of theories, the unavoidability of conceptual indefiniteness, the use of conceptual toy models, the possibility of major conceptual revision, and the quest for unified overarching conceptual frame-works. Here, as in chapter 3, the analogies are both compelling and provocative. Polkinghorne introduces his discussion of conceptual indefiniteness by exploring the paradox of wave-particle duality within quantum field theory. The resolution to this paradox relies on a property of quantum systems called “particle number.” If this property is definite (i.e., some number or other), then a system will behave in particle-like ways. If, however, this property is indefinite (i.e., no particular particle number, or more technically a “superposition” of such numbers—which is licit according to the rules of quantum theory), then the system will behave in a wave-like manner. The catch is that this resolution comes at a significant cost: one must agree not to ascribe definite particle numbers to certain quantum systems; or as Polkinghorne puts it, “no greater clarity should be sought than reality permits.” Turning to theology, Polkinghorne notes that many of the early churches—again, he simply says “the Church”—rejected the christological solutions proposed by Apollinarius and Nestorius, embracing instead the more nuanced but less transparent Chalcedonian formulation. Far from judging this to be an irrational retreat into mystery, Polkinghorne finds theology’s acceptance of indefiniteness on this issue a rational posture not wholly foreign to those who have learned to think in the idiom of quantum physics.

How compelling is Polkinghorne’s argument that analogies such as these collectively demonstrate the homologous nature of the truth-seeking strategies used by scientists and theologians? At one level, the argument is quite compelling indeed. Polkinghorne shows clearly how Christian theologians’ investigations into the nature of God throughout the centuries have at numerous points taken much the same form and leveraged many of the same rational resources as scientists’ investigations of the natural world. His decision to begin each of the 14 vignettes with an example from science and then turn to the theological analogue could leave readers with the impression that theological rationality is merely analogous to the real rationality of science, but the overall structure and tone of the book suggest rather that Polkinghorne is simply willing to let the theological ego take a hit for the sake of convincing scientists that they should not “set aside too hastily the insights [of theology] that are worthy of their careful attention.” But there is a deeper issue at  stake here. In the end, Polkinghorne hopes to convince his readers not merely that the-ology is a truth-seeking endeavor but that it is a truth-finding endeavor as well. His rhetoric consistently reinforces the idea that theologians actually know about God in much the same way that scientists know about the world. While he acknowledges that theology cannot appeal to testability as science does, he insists that theology’s own grounding in divine revelation need not entail “unchallengeable propositions mysteriously conveyed for the unquestioning acceptance of believers.” It is difficult to know how seriously to take this claim, especially when Polkinghorne’s explanation of what revelation does entail turns out to be a phenomenological account of its importance rather than an alternative epistemological account of its reception. Moreover, only a few pages later one encounters the claim that valid interpretations of spiritual encounters depend ultimately upon our “trusting acceptance” of God.

At root, then, Polkinghorne’s discussion of revelation leaves one with a sense of the incongruity of the basic epistemological frameworks of science and theology. The case he builds through-out the book for the overarching similarity between scientific and theological rationality hovers awkwardly over this fact. Were he to nuance his view of science as a “linear process in which knowledge increases monotonically” or soften his claim that “orthodoxy” lies within what has been “perceived by the Church to be in accord with fundamental scriptural and ecclesial testimony,” his argument would carry greater force. But because he refuses  either of these paths, the incongruity stands as an unresolved tension within his own perspective.

In the final chapter of the book Polkinghorne takes up the larger task of explaining the origin of the epistemic homologies he has previously identified. Drawing a further analogy, this time from evolutionary biology, he notes two distinct possibilities. When biologists find homologous features in different species they typically hypothesize either a common evolutionary lineage or the production of similarly adaptive structures via independent evolutionary pathways (so-called “convergent evolution”). Polkinghorne suggests that in the present context the appropriate analogue of ap-pealing to a common ancestor would be the thesis that “modern science owes religion a relationship of friendly gratitude since the latter historically provided the intellectual matrix that brought the former to birth.” He then suggests that the appropriate analogue of recognizing convergent evolution would be to affirm the divine Logos as the “fundamental source of the rational order of creation.” Although only the second of these approaches is explicitly theological, he clearly means for both to cast Christianity in a positive light.

The chief difficulty with this account of the homologous character of the truth-seeking strategies of science and theology is that it ignores a third possibility, namely, that a deeper appreciation of humanity’s common set of evolutionarily shaped cognitive resources would lead one to expect that our efforts to answer difficult questions would take similar shape, regard-less of the questions being asked. The emergence of similar heuristic, historical, and conceptual patterns across different traditions of inquiry, say the evolutionary psychologists, should come as no surprise given our common evolutionary history. But then the relevant backdrop for Polkinghorne’s larger argument is not just at the microscale of the rise of modern science in the context of Euro-pean Christendom or at the macroscale of a cosmos imbued with the divinely ordering Logos, but also at the mesoscale of the development of cognition over the course of the evolution of life on Earth. While it is perhaps not necessary to think of this “middle” account as undermining the other two, acknowledging the possibility of such an account does at least raise the question of whether the homologies between the truth-seeking inquiry of theology and science have any real bearing on theology’s status as a truth-finding enterprise. Polkinghorne’s finely crafted and provocative little book brings this important question to the fore and invites further reflection.