Viewed piecemeal, the individual fragments of a jigsaw puzzle don't mean a great deal. Only when painstakingly assembled to complete the picture do the tiny bits make sense.

In many ways, science is not unlike a jigsaw. Experiments yield detailed results but often they are so specific as to be of little or no general application or meaning.

The results of any single study often only gain true meaning when placed in the context of the whole picture. Stepping back to take in the big picture, in other words, is crucial to understanding.

But how do you get the big picture without having individual parts to assemble? This is where the so-called western scientific method - which aims through experiment, observation and deduction to produce reliable explanations of natural phenomena - comes into its own.

Science is good at reducing a complex problem to its constituent parts. Reductionism, as it's known, makes an unwieldy problem a lot less unwieldy to study.

[S]tereotypically, reductionists are those white-coated folk bending over equipment-strewn benches in sterile laboratories. They are not without their detractors - often people such as ecologists and ethologists, who generally prefer to treat their subjects as whole, integrated systems. Reductionism, for many of them, is a dirty word. To some extent, the divide between reductionists and holists is not unlike that between the practitioners of orthodox and alternative medicine.

Does one work better than the other? Which approach yields that elusive Holy Grail,"the truth"? That the answers are far from clear suggests that the questions may be partly to blame. For a start, what do we mean by"better" and, more importantly, by"truth"?

Without waxing too philosophical, both better and truth are relative terms. In particular, they relate to the level or scale of understanding we seek.

Take the common or garden leaf, for example. Regarded merely as the lateral outgrowth on the stem of a plant, a leaf may be described in terms of its colour, shape, texture or smell. It could also be considered in terms of its potential applications, such as in cooking or herbal remedies. Taking another tack, leaves may be thought of as the primary organs of photosynthesis - as plants' or trees' solar panels, if you like. Biochemists, meanwhile, may want to understand leaves at a chemical or molecular level, and so on.

The point is that no one approach is necessarily better than another and none will provide a once-and-for-all true account of leafiness. Each level of understanding may be appropriate in its own right. More importantly, we can only fully appreciate leaves by standing back and taking in the big picture. To do that, however, many mainstream scientists believe they need to take lots of small, precise pictures - in much the same way that the number and detail of individual pixels determine the clarity and definition of a TV screen.

In their quest for ever greater knowledge, such scientists have increasingly specialised, a trend showing no immediate sign of abating.

But there is another move afoot....