EXPLANATIONS

Since 1990, John Cornwell has been directing the Science and Human Dimension Project at Jesus College, Cambridge, and has organised a series of seminal meetings on themes at the frontiers of science. The Proceedings of two of these seminars have already appeared: Nature's Imagination and Consciousness and Human Identity. This volume explores issues around causality and the nature of explanation in science. John has delved deeply into this field himself, notably with his book Power to Harm, where he covered the trial of a man on Prozac who went on the rampage, killing and maiming a number of people in his former workplace. He reminds the reader of the framing of Eli Lilly's defence around a 'nature and nurture' determinism, which was competing with the neurochemical determinism implicit in the production of the drug itself. As the joint discoverer of Prozac, Dr Ray Fuller, put it: 'behind every crooked thought there lies a crooked molecule'. In the end, the trial was foreclosed, ironically, when the defence shifted to a free will explanation and paid off the key litigants.

The word 'explanation' literally means to unfold, as David Bohm was fond of remarking. What is unfolded is enfolded or implied in the original statement in terms of an implication. So an explanation unfolds the implications of a statement, restating them in a different form. This raises a question that is not directly addressed by the authors in this volume, namely why certain explanations are preferred to others. Jung saw this in terms of the assumptions of the dominant world-view, remarking that explanations involving spirit were preferred in the Middle Ages while these days they have to be couched in terms of matter being fundamental - indeed Steven Rose insists here that all biologists have to be materialists.

The book contains 12 contributions by experts in philosophy, physics, cosmology, mathematics (John Barrow), chemistry (Peter Atkins), biology and social anthropology. This entails a variety of discourses, disciplines and viewpoints, with some contributors asking more fundamental questions than others. Peter Lipton, Professor of History and Philosophy of Science at Cambridge, opens the batting with a sophisticated piece on features of explanation and understanding. Little is left standing by the end of his analysis, where he concludes that the nature of explanation leads to the best inference. Steven Weinberg and Tian Yo Ciao tackle distinctions between description and explanations, the latter in terms of the ontology of 'primary entities' that give rise to explanations. Weinberg deconstructs the words 'fundamental', 'deduce' and 'principle', observing that only when we have a final theory will we be able to reconstruct them again. Like others in the volume, he does not think that science can ever explain any moral principle.

The Astronomer Royal Sir Martin Rees gives an overview of cosmology, reminding readers that the most challenging frontier of science is perhaps the complex rather than the very large or the very small. We find that intricate complexity has emerged from simple laws, and Rees advances three possible interpretations. He rejects Providence and Happenstance, preferring instead the idea of the multiverse, implying a horizon beyond our reach; this in turn can mean that there are galaxies beyond the range of present-day telescopes, or galaxies that are unobservable in principle - either at all or only in a remote cosmic future. An interesting implication of Rees's view is that the laws underlying the multiverse may allow variety among the universes, however strange this may seem to us from our vantage point.

The issue of anthropomorphism is vigorously tackled by David Hanke from the Plant Sciences Department in Cambridge. His premise (and problem) is that 'we persist in making (literally) sense of a world that we now know to be senseless'. Some readers, like myself, will question the categorical nature of this statement, but it is true that a consistent neo-Darwinism should have no place for teleological terms. Hanke defines teleology as 'the mental habit of supposing that objects or events have a purpose'. He traces this right back to the great man himself and the way in which Natural Selection 'slipped seamlessly into the place of the Creator: the Natural Selector as the acceptable new face of the Great Designer'. 'Selection' is itself an anthropomorphic term, as are 'fitness', 'function' and 'success'. Hanke's view is that there is no selection, only differential survival'.

His next interesting point arises from his definition of intuition as 'prejudice acquired by long usage'. Lewis Wolpert made the point in his book The Unnatural Nature of Science that many scientific theories turn out to be counter-intuitive, and yet we are inclined to favour the explanation that feels right; but 'feels right' in relation to what? The existing structure of knowledge! This is not the way in which new discoveries are made: as Proust said, we need new eyes. Hanke illustrates his point with a fascinating example from his field about the response of plants to light and darkness. Contrary to the received opinion that darkness is simply the absence of light (interesting theological overtones here), it was discovered that the plant in the dark is not in an unactivated state. Researchers found that almost as many genes were upregulated in response to a dark signal as were induced by light, and yet they refer to these as 'light-downregulated genes'! So for Hanke, teleology is a 'straightjacket for the mind'. The converse may apply in other fields, but this was beyond Hanke's scope.

There is a vintage contribution from Steven Rose, drawing heavily on his excellent book Lifelines. He advocated an epistemological pluralism relating to different levels of description, combats Steven Pinker's informational model of the brain, and supports the science of self-organisation. He also remarks that the split between developmental and molecular biology led the first to study similarities and the second differences. He ends with his own 'biological decalogue for the millennium', which forms a new and constructive point of departure for the future of biology.

Other essays ask 'what it is not like to be a brain?' (Colin McGinn) and the advance from explanation to interpretation in social anthropology (Jack Goody). Finally, Jon Turney looks at the challenges of translating technical into popular science, especially with the judicious use of metaphor. The book is a valuable contribution to the popular understanding of philosophy of science, and is written in a way that will intrigue the general reader as well as stimulate the specialist.