A common aspect of the modern scientific method is to break problems into fundamental constituent parts and study how, precisely, they fit together.

This utilization of analysis happens at both a literal and metaphorical level: particle physics search for the ultimate physical particles of nature that make up all others, while they simultaneously seek out an underlying framework of principles that govern all interactions of matter.

This type of approach is typically known as reductionism. The problem, however, is that different people mean very different things by that word.

To some, the word reductionist conjures up images of an inflexible, hierarchical autocrat using fancy highfalutin' prose to justify some phoney pre-eminence of her research agenda.

Some of this suspicion is understandable. From the perspective of a population biologist or meteorologist, the oft-quoted sexy pronouncements of theoretical physicists, with their "theories of everything written on a T-shirt," sounds a lot like hubris and inappropriately trivializes what they do as merely "derivative."

Much of this is, of course, just silly. No reasonable physicist would ever suggest that there aren't a bevy of interesting and exciting unanswered questions in all fields of scientific endeavour. But beneath the self-serving rhetoric and hurt feelings, there are some truly deep questions at the heart of this issue.

Steven Weinberg, the Nobel Prize winning physicist often (falsely, I think) described as an "arch-reductionist," states in his book Dreams of a Final Theory that in his view, elementary particle physics is more fundamental than other branches of physics not because it is "more mathematically profound or that it is more needed for progress in other fields or anything else, but only that it is closer to the point of convergence of all our arrows of explanation."

By this, Weinberg means that the underlying principles that govern elementary particle physics are fundamental in that any other branch of physics that involves collections of these particles must assume these laws and principles as key building blocks.

Weinberg uses an analogy of a lynch mob to stress this point. We can derive laws about how mobs behave, he says, "but if we ask for an explanation of why such laws hold, we would not be very happy to be told that the laws are fundamental, without explanation in terms of anything else. Rather, we would seek a reductionist explanation precisely in terms of the psychology of individual humans."

In this way, Weinberg concludes that all reasonable people are really reductionists at heart and that any attempts to formally distinguish themselves from the reductionist tag are merely confused, relying on a false definition.

But some reasonable people disagree. In particular, there are those who feel strongly that fundamentally new concepts somehow emerge at different levels of our experience. (Weinberg, too, believes this, but the question, as always, is where precisely to draw the line between levels.)

Philip Anderson, another Nobel Prize winning physicist, states: "At each stage, entirely new laws, concepts and generalizations are necessary, requiring inspiration and creativity to just as great a degree as the previous one. Psychology is not applied biology, nor is biology applied chemistry."

There is much to be said for this view. To take an extreme example, it's hard to imagine that whatever revolutionary discovery comes out of cosmology will ever tell us anything meaningful about the origin of life, say, or the best way forward on the joint removal of international trade barriers.

But the difficulty with splitting things up into separate levels is that there must be some clear way of distinguishing them -- a way of defining, if not predicting, when one level starts and another stops.

This is the ultimate dream of the complexity theorists, researchers who utilize chaos theory and other techniques to try and discover a meta-theory of nature somehow justifying precisely how these separate levels with their consequent emergent laws arise.

It is a rather ambitious dream, to say the least -- perhaps not surprisingly, the results have not, so far, been overwhelmingly positive. Many now believe that such an all-inclusive framework is simply untenable.

Still progress rapidly continues throughout many fields separated by barriers we may never fully understand.

But as long as we all continue to ask "why?" and push the limits of each existing framework of understanding, we will continue to drive our knowledge further along the road of discovery.