Preface
Polkinghorne explains the book’s central thesis: science and theology share significant “cousinly relationships” in their truth-seeking methods, contrary to the common view that they are chalk and cheese. He rejects “quantum hype”—facile transfers of quantum paradox to other disciplines—and instead employs paired discussions, each feature illustrated first by physics then by theology. He hopes theologians will engage more seriously with science and scientists will recognize theology’s rational scrupulosity. The book is dedicated to his late wife Ruth.
Chapter 1: The Search for Truth
Critical Realism in Science and Theology
Both science and theology are truth-seeking enterprises grounded in critical realism—acknowledging epistemic precariousness while claiming genuine access to truth. Polkinghorne draws on Michael Polanyi’s “personal knowledge” to show science involves skilled judgement within a community, not mechanical rules. Both disciplines require hermeneutic circles linking encounter with interpretation, though theology’s circle is more complex due to its diachronic, revelatory, and existential character.
Four Differences Between Theology and Science
Theology differs from science in four ways: its diachronic character (insight spread across centuries, requiring dialogue with the past); God’s initiative in revelation (versus the scientist’s initiative in experiment); the fragmentation of world faiths (versus science’s near-universal assent); and the existential demands of religious belief (versus the more detached character of scientific conviction). These differences make the defence of critical realism more subtle in theology but do not undermine it.
Five Points of Cousinly Relationship
Polkinghorne outlines five parallels between the development of quantum physics and Christology: (1) enforced radical revision (wave/particle duality and divine/human language about Jesus); (2) periods of unresolved confusion (1900–1925 physics; the NT without systematic theology); (3) new synthesis and understanding (quantum theory; Trinitarian and Chalcedonian formulations); (4) continued wrestling with unsolved problems (the measurement problem; apophatic limits of theological language); (5) deeper implications (the EPR effect; Moltmann’s crucified God and theodicy).
Chapter 2: Comparative Heuristics
Techniques of Discovery: Experience and Understanding
Physics advances through creative interplay between experiment and theory—Einstein’s general relativity validated by Mercury’s perihelion, string theory’s current speculative phase lacking experimental discipline. Theology has “Christology from below” (grounded in historical evidence) and “from above” (conceptual coherence using philosophical tools). Neither discipline progresses through pure empiricism or pure speculation; both require disciplined interaction between assessed experience and imaginative interpretation.
Defining the Problem: Critical Questions
Quark theory succeeded by asking two sharp questions in sequence: first taxonomic order among particles, then the structural reality of quarks confirmed by deep inelastic scattering despite quarks never being observed in isolation. Christology asks three critical questions: Was Jesus resurrected? Why did the first Christians use divine language about him? What was the basis for their experience of transforming power? Functional or inspirational Christology fails to answer these; only incarnational understanding does justice to the New Testament witness.
Expanding Horizons: New Regimes
Phase transitions—such as superconductivity discovered by Kamerlingh Onnes in 1911—demonstrate that new physical regimes require new concepts while underlying laws remain consistent. Miracles, particularly the resurrection, are theological analogues: a new regime requiring new understanding, not a capricious “celestial conjurer” trick. The resurrection is best understood as a “sign” opening a window into deeper divine reality, analogous to superconductivity revealing deeper structure beyond Ohm’s law.
Critical Events of Particular Significance
Compton scattering in 1923 clinched the particle-like behaviour of light, dispelling all doubt. The resurrection is the analogous critical event for Christology. Polkinghorne examines the evidence: the enigmatic character of the appearance stories (difficulty of recognition, strange silence of Scripture, absence of future-hope themes), the empty tomb (women as witnesses despite their legal unreliability, the absence of secondary burial), the shift of the Lord’s Day to Sunday, and the transformation of frightened deserters into bold proclaimers.
Chapter 3: Lessons from History
Growing Recognition of Deeper Significance
In physics, Planck’s quantum hypothesis and Bohr’s model evolved through successive refinements into full quantum theory by 1925–26, demonstrating coherent growth in conceptual understanding. Christology followed a parallel trajectory: Jesus’ own self-understanding (Abba, Christ, Son of Man)—none intrinsically divine—developed through the early Church’s use of “Lord” and Old Testament imagery (second Adam, Wisdom, Logos in John’s Prologue), culminating in the Chalcedonian definition. Both fields discovered significance far greater than originally apparent.
Collateral Developments: Waves and Spirit
The concept of waves evolved from directly perceptible sea and sound waves, through Maxwell’s electromagnetic waves and the discredited luminiferous aether (abolished by Einstein’s special relativity), to Schrödinger’s abstract probability waves—an indispensable concept whose realistic interpretation matured beyond naive reification. The concept of Spirit followed a parallel arc: from Genesis’ ruach hovering over chaos, through prophetic bestowal, Pentecost, Paul’s diverse gifts and personal intercession, John’s Paraclete, to the fourth-century recognition of the Holy Spirit as the Third Person of the Trinity. Both concepts were preserved while their interpretation grew subtler.
Tides of Fashion
Relativistic quantum theory cycled through popularity and neglect: Dirac’s initial discoveries, infinities crisis, S-matrix theory as a leaner alternative, and gauge theory’s eventual resurgence. Christology followed a parallel arc: the first quest (Reimarus, Strauss), then rejection (Kähler, Schweitzer’s devastating critique showing liberal lives of Jesus reflected their authors’ era), Bultmann’s demythologisation, and the new quest’s return to historical foundations. Both disciplines had to return from fashionable substitutes to their foundational roots.
The Role of Genius
Exceptional individuals at propitious moments shaped both fields irrevocably. Heisenberg, Schrödinger, and Dirac each brought distinctive perspectives to quantum theory in the mid-1920s, founding the discipline through sheer creative insight. Analogously, Paul, John, and the writer to the Hebrews provided the deepest theological reflections in Christianity’s first generation, establishing conceptual frameworks that shaped all subsequent thought. Both cases demonstrate irreducible dependence on gifted minds seizing their moment.
Living with Unresolved Perplexities
Neither quantum physics nor theology has resolved its deepest problems. Physics lives with the measurement problem, difficulties combining quantum theory with general relativity (string theory’s untestable speculations), and quantum-chaos incompatibility. Theology faces the problem of evil: the free-will defence addresses moral evil, while the free-process defence suggests physical evil is the shadow side of a creation allowed to “make itself.” Most profoundly, the Christian God is the crucified God—a fellow sufferer, not a detached spectator. Both disciplines must live constructively with unresolved perplexity.
Chapter 4: Conceptual Exploration
Progressive Theoretical Development: From Models to Theory
Physics uses phenomenological models (Bohr’s atom, nuclear “cloudy crystal ball” model) that are eventually replaced by deeper unified theories (quantum field theory, QCD). Sometimes progress comes through radical conceptual re-evaluation, as with Einstein’s relativity. Christology follows the same pattern: adoptionism (God adopting a worthy man) proved inadequate; kenotic Christology (Philippians 2) and Irenaeus’s argument that salvation requires both true divinity and true humanity pushed understanding deeper. The New Testament titles are like phenomenological models; Nicene homoousios and Chalcedon’s “two natures in one person” are like fundamental theory—though Polkinghorne concedes Chalcedon resembles pre-1925 physics, holding paradox without full theoretical resolution. Apophatic theology and Baillie’s “central paradox” of grace and free will mirror physics’ acceptance of irreducible mystery.
Indefiniteness: A Cloud of Unknowing
Quantum field theory resolved wave/particle duality through ontological flexibility: indefinite particle number in wave-like states allows entities to be neither simply waves nor simply particles. Theology can take heart from this. Chalcedon’s less specifically articulated formula accepts a degree of mysterious indefiniteness analogous to quantum indefiniteness—refusing to reduce Christ’s person to a neat logical scheme just as quantum theory refuses to force entities into classical categories.
Toys of Thought: Thought Experiments
Einstein’s thought experiments against Bohr clarified quantum principles through conceptual pressure rather than laboratory work. Theology employs eschatological pictures (Revelation 21–22) as thought experiments exploring the coherence of Christian hope—not literal maps or timetables, but disciplined imaginative probes of whether faith’s promises are internally consistent.
Major Revision: Determinism and Divine Temporality
Physical determinism has been overturned by quantum theory and chaos theory, disproving the clockwork universe and opening conceptual space for ontological openness consistent with divine action and human agency. Polkinghorne parallels this with a major theological revision: the classical atemporal view of God (Boethius, Aquinas, Calvin) is being revised toward dipolar views where God genuinely engages with temporal process. Three considerations support this: science reveals a world of true becoming; scripture depicts God involved in history; and divine love requires immanence in time, not merely distant sovereignty.
Grand Unified Theories: GUT and the Trinity
Physics pursued unity from Galileo’s identification of celestial and terrestrial physics, through Newton’s universal gravity and Maxwell’s electromagnetism, to Weinberg-Salam electroweak theory and the ongoing quest for grand unification (string theory’s speculative reach remains untested). Trinitarian theology pursued analogous unification: the economic Trinity (God known as Father above, Son alongside, Spirit within) led to the immanent Trinity. Modalism and tritheism were rejected; Greek Fathers developed perichoresis and the subtle hypostasis-ousia distinction. Crucially, both fields discovered deep relationality: the Trinity’s “God is love” and physics’ entanglement and spacetime-matter coupling confirm reality is fundamentally relational. Polkinghorne concludes that the true “Theory of Everything” is trinitarian theology.
Chapter 5: Cousins
Biological Homologies as Analogy
Polkinghorne opens by drawing on comparative anatomy: biological homologies are explained either by common ancestry or by convergent evolution toward structures that are both advantageous and accessible. Simon Conway Morris’s work on convergent evolution—where eyes, for instance, evolved independently multiple times—suggests that the possibility-space of viable structures may be more constrained than assumed. He uses this dual explanation as an analogical lens for the cousinly kinship between science and theology.
Common Ancestry: Science Born from Christian Thought
The first explanation traces modern science to its birthplace within medieval Christian intellectual culture. The doctrine of creation—a freely created yet orderly world—encouraged the expectation of deep, discoverable order that required observation and experiment, not pure reason alone. This theory-experiment synthesis, pioneered by Galileo, drove the scientific revolution. Early scientists like Galileo and Newton saw no conflict between the “two books” of Scripture and Nature. The parting of ways came in the mid-18th century when triumphalist claims for the sufficiency of scientific method alone displaced theology, though notable scientists like Faraday, Maxwell, and Kelvin remained devout.
Deep Underlying Forms: The Logos Doctrine
The second explanation appeals to the Logos doctrine as the deep structure linking science and theology. John’s Gospel identifies the Word (Logos)—through whom all things were made—with the incarnate Christ. Colossians 1:16–17 identifies Christ as the one through whom all things are created and in whom they cohere. The Logos also enlightens everyone (John 1:9), which Polkinghorne connects to the philosophical endorsement of critical realism. The cousinly relationships explored throughout the book derive from the universe being a true cosmos created through the divine Word.
Implications and Conclusion
Because the cosmos originates in the divine Logos, religious believers should welcome all truth including scientific truth, and scientists pursuing understanding to its fullest will find themselves drawn toward religious belief—the search for the Logos. Polkinghorne concludes that the cousinly relationships between science and theology find their “most profound understanding in terms of that true Theory of Everything which is trinitarian theology.” The deep rational order and relationality manifest in the physical world reflect the character of the trinitarian God whose deepest reality is perichoretic love.