Hoping distant cousins will kiss

As a student scientist and a Church of England ordinand I should perhaps have felt a conflict between my studies and my religion. I never did - thanks in large part to C. A. Coulson, a mathematical physicist and a leading lay member of the Methodist church, who introduced me to the mysteries of quantum theory. His 1958 McNair lectures, published as Science and Christian Belief, gave intellectual confidence to a whole generation of scientist-Christians.

John Polkinghorne is the best known and most prolific of Coulson's successors, Christians from the top of the scientific community who have witnessed to the compatibility of science and religion in the face of the aggressive scientific atheism preached by Stephen Hawking, Richard Dawkins and others. But where Coulson simply demonstrated that science was not inherently hostile to religious faith, Polkinghorne goes further and actually engages in technical theological issues such as the two natures of Christ.

The alleged conflict between science and religion depends on two assumptions. First, that both disciplines aim to provide a descriptive account of the way the world is, and secondly that their two pictures are incompatible. Polkinghorne halves his chances of successfully challenging the conflict when he endorses - indeed positively champions - the first of these assumptions. Other theologians and philosophers of science may be drawn by the siren voices of postmodernism; he will have none of it. Lashing himself to the mast of the good ship "critical realism", he stoutly refuses to deny his basic belief "that the advance of science is concerned not just with our ability to manipulate the physical world, but with our capacity to gain knowledge of its actual nature".

Polkinghorne's commitment to scientific realism has its counterpart in his theology, which is also "critical realist". He describes the scientific and theological methods as having a "cousinly relationship": neither gives unmediated access to things-in-themselves (the critiques of Hume and Kant are acknowledged) but both yield true, albeit partial information about the way the world is. What most strikes him is the "many-levelled character of human encounter with reality" - especially its moral and aesthetic dimensions - and he finds its "best explanation" in theism.

The gratuitous dogmatism of anti-religious writers such as Dawkins is easily exposed by Polkinghorne's criticism. Less convincing is his own positive contribution. A modified version of natural theology, "insightful, rather than logically demonstrative", it will hardly bear the weight required of it. Not only does it fail to produce by itself a recognisably Christian deity (of which more later), it also turns out to be less "scientific" in its method than the author implies.

Just how distant are the "cousins" is shown up when specific cases are discussed. The chosen topics are, on the science side, the (almost inevitable) particle/wave duality of light and, representing theology, the divine/human duality of Christ. Polkinghorne discerns five stages in the development of quantum theory that are paralleled in the development of Chalcedonian Christology. How significant these parallels really are is open to question, but even if they are acknowledged, there remains an unbridgeable gap between the two cases. Particle/wave duality is an empirical observation that demands a theoretical explanation. Christ's human/divine duality is a theoretical requirement demanded by a particular understanding of Christ's role as the Saviour. There is no real comparison between the two dualities.

The hidden factor here is the place of revelation in the theological enterprise. In many ways the whole debate over science and religion is an aspect of an older battle between natural and revealed theology. As their names imply, natural science and natural theology have a shared starting point in the observation of nature, rather than in revealed or a priori truths. It follows that in many ways they have more in common with each other than either has with revelation.

This problem is barely mentioned in the book under review, but it emerges starkly in a report of the Doctrine Commission of the Church of England, We Believe in God (1987). This document also compares the methods of science and theology, and demonstrates the ultimate gulf between them. In places the report speaks positively of the similarities between science and theology, declaring that, "What theologians offer are much more like scientific 'models' than literal descriptions." And later on: "Like the hypotheses used by scientists . . . the models used in the Bible to describe God are valid up to a certain point of experience and understanding, but (in theory, at least) they are corrigible . . ." Those parentheses give the game away. The truth of the matter is set out in the report's first chapter, which admits: "We are concerned . . . with an ultimate Reality which we believe to exist, and to which we claim to have privileged access through the Scriptures and tradition preserved for us by the Church."

It may appear unfair to quote against an author a document in whose writing he played no part. The question is too important to ignore, however, and the report does make clear how theology is actually practised within the church of which Polkinghorne is an ordained minister. More than this, Polkinghorne himself makes it clear that when physicists such as Hawking and Paul Davies speak of "the mind of God", this is a concept that by itself falls a long way short of "the God and Father of Our Lord Jesus Christ". He also quite deliberately distances himself even from other scientist-theologians (he names Ian Barbour and Arthur Peacocke) where he feels that they are inclined in various subtle ways to subordinate theology to science. He, by contrast, "while wishing to ensure that theological understanding is consistent with what science tells us about the structure and history of the physical world, will insist that theology is as entitled as science to retain those categories which its experience has demanded that it shall use, however counterintuitive they may be".

He gives as an example of such theological categories the incarnational terms in which Jesus Christ is understood by Christians. We have already seen how his claimed parallel between scientific and theological method broke down in this case. It would be restored, to some extent at least, if the human/divine duality that I labelled a theoretical requirement were redesignated a revealed truth, comparable to - indeed more certain than - the empirically observed particle/wave duality of light. That is presumably how the Doctrine Commission would view the matter, involving as it does the "claim to privileged access to an ultimate Reality". In the absence of any further evidence, we must assume that this is also Polkinghorne's view, and it is one that sits awkwardly with the claim to a "cousinly relationship" between science and theology.

I actually go along with much more of what Polkinghorne says than this review so far might imply. The difficulties arise from his being wedded to realism.

For instance, when he writes, "I believe that nuclear matter is made up of quarks which are not only unseen but which are also invisible in principle. . . . A similar conviction grounds my belief in the invisible reality of God," I accept the parallel. But in my case the same logical steps lead to opposite conclusions - because the starting point is different. For me, invisible subatomic particles are first and foremost hypothetical constructs. Whether entities that correspond to them "really exist" is beside the point. Their value - their reality if you like - lies in their practical usefulness to theoretical physicists. In a similar way, the reality of the invisible triune God is to be found in the "godly, righteous and sober lives" of faithful Christians who are guided and inspired by the story of the One who "died for our sins and rose for our justification".

So long as we cling to realism - even critical realism - Polkinghorne's project of a theology and a science that share essentially similar methods will founder upon the rock of revealed theological truths that have no parallel in science. By contrast, from a standpoint that sees both science and theology as disciplines that are constructive rather than descriptive, the absolute claims of revelation will be undermined. Then the way will be open for to us all to share the fruits of the inspired, but not infallible, insights of scientist and theologian alike.

The Revd Anthony Freeman is managing editor, Journal of Consciousness Studies.