If science is about reductionism, how come we are drowning in a sea of data? asks Sara Abdulla

It is the marvel of the universe that, with a limited number of elementary particles, we have ended up with countless galaxies and highly organised, living, breathing, desiring organisms. For millennia, humanity has tried to explain this wonder. Since the Greeks that quest for explanation has had as its holy grail a Theory of Everything - the notion that we can explain the world in terms of universal principles governing its ultimate constituents.

Although our ideas about what those ultimate constituents might be has changed considerably over the years - the Greeks considered earth, air, fire and water to be the basic building blocks - science has always been based practically, if too philosophically, on "reductionism", the doctrine that any complex system can be understood in terms of its isolated components.

But is the difference between a living and a non-living thing purely illusory? Could we reconstruct a person from liver to love and predict their every thought and action if our inventory of their constituent elements were complete enough?

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If that is the aim, we are in for a long wait. Though advances in genetics, structural biology and biochemistry have transformed our understanding of cellular processes at the molecular level they have also brought home just how awesomely intricate living organisms really are. From Socrates and Plato through Kant to Ernest Nagel, Richard Lewontin and Alan Garfinkel there have been many philosophers who foresaw that, as Nagel puts it "the reduction of biology to physicochemistry is inherently impossible". But their quiet reason went unheeded because, for the most part, as Lewis Wolpert of University College London, says "It works!" Now that biologists are standing waist-deep in data, and are little wiser for it, disillusionment has set in. Ten years ago John Maddox, then the editor of Nature, the premier science magazine, began an editorial entitled "Finding the Wood Among the Trees" with the question: "Is molecular biology running into a dead end?''. "Is there a danger,'' he went on to ask, "that the accumulation of data will get so far ahead of its assimilation into a conceptual framework that the data will eventually prove an encumbrance?'' A decade down the line nothing has stemmed the relentless flood of information and no one has answered the question: what are we going to do with it all?

Chairing a meeting of biologists and philosophers of science at the Ciba Foundation in London this week, Wolpert, himself an evangelical reductionist ("science is reductionism, to me the cell is just complicated chemistry"), championed the pragmatic approach. "It's not about reductionism or antireductionism - it's about reduction to what works. The trick is to reduce to the most appropriate, useful and suitable level that is still consistent with all the others," he said.

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But moving between those "levels" can be problematic. Steven Rose, professor of biologyat the Open University whose book Lifelines: Beyond Reductionism will be published by Penguin in September, believes there is "a translation problem". "We talk about the molecule in one language and the organism in another and mistakenly assume that one is the primary language and one the secondary". Rose feels this leads to an impoverished, blinkered, "pecking order" of scientific explanation, especially in psychology and sociobiology where it can result in "victim-blaming and a distraction from the real tasks that both science and society require".

Some methodological reductionism is essential to research. As Ernest Nagel jokes in The Structure of Science, "a stone and a cat dropped from a height exhibit behaviours which receive a common formulation in the laws of physics." But no amount of subtle structural chemistry has enabled us to predict protein folding. Nagel points out that the problems arise when we lose sight of the fact that biology, unlike any of the other sciences, is in the business of understanding the function of a system as well as its form.

Sara Abdulla is science writer-in-residence at the Ciba foundation, where a conference on "The Limits of Reductionism in Biology" took place this week.