a) Agential Models of God’s Interaction With the World

Agential models deal explicitly with contemporary science and its philosophical implications to explore the concept of God as interacting with, but not intervening in, the world. They, in turn, include three distinct approaches, each of which has been widely developed in the theology and science literature: top-down causality, whole-part constraints, and bottom-up causality. However, most scholars insist that a combination of these approaches will be needed eventually for an adequate account of non-interventionist divine action.

i) Top-down causality. This approach focuses on the possibility of ‘top-down’ causal relations between properties and processes at higher and lower levels of complexity: the term ‘top-down’ means that processes at the higher levels effect those of lower levels. Peacocke explores models involving top-down causality in light of Big Bang cosmology: God acts on the ‘world-as-a-whole’ in order to bring about special events in nature and history, including revelation.Murphy, Clayton, Peacocke and Theo Meyering discuss divine action and the neurosciences in light of the ‘mind/brain’ problem (i.e., is the mind, which emerges from the brain, capable of effecting the brain?), relying on supervenience and holist epistemology.(See the ‘miniscience’ section below on cosmology and the neurosciences below). The challenge to this approach is to show how God’s action through top-down causality can bring about actual changes in the processes at lower levels if they are governed by classical physics.

Note: “Supervenience” can be thought of as a more technically-detailed form of top-down causality. Its roots lie in philosophical ethics where it describes the multiplicity of relations between moral and nonmoral properties. We will return to this approach below.

ii) Whole-part constraints. This approach stays within one level of complexity. ‘Whole-part constraints’ refers to the effects of the system as a whole on its parts (though these effects are transmitted entirely by efficient causes; compare with quantum ‘whole-part causality’ below). A helpful example is the Bérnard phenomenon in fluids where, beyond a critical point, individual molecules move in hexagonal ‘cells’ caused by the fluid being bounded by its container and by the effects of the container being conveyed by inter-molecular collisions throughout the fluid. Whole-part models typically draw on recent developments in non-linear, non-equilibrium thermodynamics as applied to systems open to their surrounding environment. Peacocke has used this approach to point to novelty emerging in the world. Whole-part themes become one way of viewing God as bringing about special events through God’s interaction with the whole of which these events are a part. The challenge again is that thermodynamics is part of classical physics and thus fully deterministic, making God’s non-interventionist action problematic.

Science minisummary: thermodynamics.In the 19th century, thermodynamics, the study of heat transformation and exchange, was concerned with closed systems (i.e., systems which do not exchange matter or energy with their environment). In such systems although the total amount of energy E is always conserved (the “first” law, ΔE=0), the amount of available energy inevitably decreases to zero (the “second” law); equivalently, the entropy S of the system, defined as the amount of unusable energy, increases to a maximum: ΔS>=0. During the 20th century, the field was broadened to include open systems (i.e., systems which exchanged matter and/or energy with their environment). These first included non-linear systems in which effects on the system were highly amplified, and then non-linear systems far from equilibrium in which spontaneous fluctuations were even more fully amplified. Such systems demonstrated the surprising phenomena of ‘order out of chaos’, to use Ilya Prigogine’s famous phrase: they could spontaneously move to greater forms of organization, driven always by the internal production and dissipation of entropy (i.e., ‘dissipative systems’), and though, of course, the total entropy of the open system plus its environment obeyed the second law.Two final points: 1) Whether ‘entropy’ applies to the universe as a ‘closed’ system is subject to intense debate, as we will see below. 2) Although most physicists reduce thermodynamics to dynamics, thus explaining (away) time’s (thermodynamic) arrow, Prigogine and others insist it should be the converse. In any case, non-linear, non-equilibrium thermodynamics points to at least one form of novelty and apparent openness in nature, although it still comes (pace Prigogine) under the rubric of deterministic classical dynamics, and, like chaos theory (below), rendering its portrait of novelty in terms of epistemic ignorance.

Others have drawn on chaos theory and complexity in discussing divine action.Polkinghorne has been particularly committed to arguing that chaotic phenomena point to the fundamental openness of nature, and that such openness could lead to a non-interventionist understanding of divine action.These suggestions have been picked up by Edwardsand developed in detail by Gregersen,but the appeal to chaos theory, at least in its present form, is open to severe criticisms similar to those regarding thermodynamics --- namely that it is still a part of classical physics.

Science minisummary: chaos theory.Over the past three decades, the study of chaotic systems has dramatically expanded from physics to include all the natural and even social sciences. Chaotic phenomena now include such physical and biological systems as the weather, water dripping from a faucet, bands in the rings of Saturn, oscillations in the populations of organisms, and the fluctuations of populations in complex ecosystems. In physics, though, chaotic systems are ‘classical’ in scale and thus subsumable in principle under classical mechanics with its deterministic laws of motion. Still even for the simplest systems, minute uncertainties in the initial conditions and the effect of countless interactions with other systems in nature, together with unusual characteristics in the underlying mathematics (e.g., ‘strange attractors’) make complete predictability impossible even in principle. Surprisingly, then, chaos breaks the long-standing philosophical link between determinism and predictability. Still since it is describable by deterministic equations, chaos theory supports a strictly deterministic philosophy of nature, although within subtle epistemic limits.

It is possible, however, as Polkinghorne suggests, that chaotic systems may one day be more accurately described by more complex theories, sometimes referred to as ‘holistic chaos’. The current deterministic laws would then be seen as simple approximations to holistic chaos through what Polkinghorne calls ‘downward emergence.” Finally, the new theories of holistic chaos would, hopefully, suggest an indeterministic interpretation.It is also possible that a satisfying connection will be found between chaos at the present, classical level, and quantum mechanics(sometimes referred to as ‘quantum chaology’), suggesting that the uncertainty in the initial conditions that, together with coupling to the environment, drive chaotic behavior is at least partially due to quantum indeterminism.

iii). Bottom-up causality. In this approach, God acts at a lower level of complexity to influence the processes and properties at a higher level, either acting as one among other factors or as fully determining them. This approach requires that the lower level be ontologically indeterministic for God to act in that level without intervening in its processes.

A number of scholars have focused on quantum mechanics as indicative of an indeterministic ontology at the subatomic level, and from there have discussed a non-interventionist view of objective, special divine action. A number of important but technical distinctions about divine action in this context (and others) surface in the literature:i) If specific quantum events occur without a sufficient natural cause, one can think of God as acting to bring them about, either by acting in, through and together with the processes of nature (i.e., ‘mediated’ divine action) or unilaterally (i.e., ‘unmediated’ divine action). ii) God may be thought of as acting directly at the quantum level (i.e., these acts of God are ‘basic’ acts), but the ‘objective, special events’ we attribute to God at the macroscopic level are in this interpretation the indirect result of them as they ‘percolate’ up the levels of complexity and ‘size’. iii) This approach to divine action does not imply a ‘God of the gaps,’nor that God is reduced to a natural cause; moreover, God’s actions, though objective, would be hidden from scientific methods.iv) Finally, one may argue that God acts with nature in every quantum event or only in some.

These arguments prove particularly fruitful in discussing God’s action in evolution, where genetic mutations are at their core a quantum process (see Part 2, C, 2 below). Those who have explored this approach to non-interventionist special divine action include Karl Heimand William Pollardin the 1950s, Mary Hesseand Donald MacKayin the 1970s, and recently and in detail by Nancey Murphy,Tom Tracy, George Ellis, Mark W. Worthing,Christopher F. Mooney,Phil Clayton and me.It has been criticized by a number of scholars including Peacocke,Polkinghorne, and Saunders. The challenge here includes the fact that quantum physics can be given a compelling interpretation in terms of ontological determinism (eg., David Bohm), making the case for indeterminism far from settled. In addition, quantum physics raises tremendously complex, and as yet unsettled, philosophical and technical problems including: the measurement problem / collapse of the wave-function (how and when does a quantum event ‘occur’ and lead to macroscopic effects?) and non-locality / non-separability (why do once interacting, now vastly separated, particles continue to act in some ways as though they remained part of a single system?) and the challenge to classical ontology and critical realism (how does one speak of the ontology of quantum processes?). Future research in theology and science should address these questions with rigorous detail if progress is to be achieved in the problem of divine action in light of science.

Science minisummary: Quantum mechanics.The empirical basis for quantum physics lies in such phenomena as blackbody radiation, the photoelectric effect, the specific heats of solids, the stability of the structure and the emission spectrum of atoms, all of which remained unexplainable in terms of classical physics. In 1901, Max Planck solved the blackbody problem by proposing that energy is quantized: it is available in discrete, not continuous, amounts. The quantization of light as ‘photons’ by Einstein in 1905 explained the photoelectric effect as well as the specific heat two years later. In 1913 Niels Bohr predicted the emission spectrum for hydrogen with a simple ‘planetary’ model of the atom in which the angular momentum of the orbiting electron, and thus the size of its orbits, are quantized. In 1924, Louis de Broglie attributed wave-like behavior to particles as the converse of energy quantization. Based on this idea, Erwin Schrödinger developed the wave equation which has proved to be foundational for quantum mechanics, Werner Heisenberg announced the uncertainty principle (and an alternative, but mathematically, equivalent formulation to that of Schrödinger), Wolfgang Pauli discovered the exclusion principle; by the end of the decade (nonrelativistic) quantum mechanics was basically complete.

Conceptual problems: Still, almost a century later, major conceptual problems persist in interpreting quantum mechanics:

---the Schrödinger equation propagates continuously in time but ‘collapses’ discontinuously in a process not described by the Schrödinger equation when a particle interacts with a classical system (often called ‘the measurement problem’);

---the Schrödinger equation describes the propagation of the wave function ψ but this is a complex variablewhose squared value ψ² represents information about the quantum system;

---a composite quantum system displays a holistic character entirely unlike classical composite systems (what can be called ‘whole-part causality’ as distinct from ‘whole-part constraints’): once interacting, now vastly separated, particles continue to act in some ways as though they remained part of a single system, as underscored by the “EPR” paradox in the 1930s and Bell’s theorem in the 1960s and now referred to as ‘non-locality’ and ‘non-separability’;

---’chance’ in quantum mechanics (i.e., quantum statistics) is not only strikingly different from classical chance (as in the familiar ‘bell curve’), it actually gives rise, in a ‘bottom-up’ way, to the basic features of the classical world, including the impenetrability of matter.

Philosophical issues: Quantum mechanics can be interpreted philosophically in a variety of conflicting ways, and so far we know of no experimental basis for choosing definitively between them. These include ontological indeterminism (Heisenberg), ontological determinism (Einstein, David Bohm --- as stressed recently by Jim Cushing), or many worlds (Everett); as involving consciousness (Von Neumann, Eugene Wigner, Roger Penrose), non-standard logic (Gribb), or consistent histories (Bob Griffiths, Chris Clarke).It is particularly important to note that Bohm’s approach assumes an underlying, deterministic ontology; the implications of his approach for a philosohy of nature and for theology have received some attention.It is also important to recognize that all of these interpretations challenge classical ontology, with its core concepts of waves, particles and locality, as well as a critical realist philosophy of nature. In any case, quantum mechanics, at least compared to the other sciences surveyed here, can plausibly be said to offer the strongest reasons for expecting that the ontology of nature at the lowest levels at least is indeterministic.

Contributed by: Dr. Robert Russell