From complexity to reductionism and back to complexity

Edward O. Wilson in his Consilience describes the two fundamental steps of science to understand Nature. First, you need to break down the processes into simple blocks. That is reductionism. Then you need to build back the complexity of the system. "To dissect a phenomenon into its elements, [...] is consilience by reduction. To reconstitute it, and especially to predict with knowledge gained by reduction how nature assembled it in the first place, is consilience by synthesis. That is the two-step procedure by which natural scientists generally work: top down across two or three levels of organization at a time by analysis, then bottom up across the same levels by synthesis" (Chapter 5).

"The greatest challenge today, not just in cell biology and ecology but in all of science, is the accurate and complete description of complex systems. Scientists have broken down many kinds of systems. They think they know most of the elements and forces. The next task is to reassemble them, at least in mathematical models that capture the key properties of the entire ensembles. Success in this enterprise will be measured by the power researchers acquire to predict emergent phenomena when passing from general to more specific levels of organization. That in simplest terms is the great challenge of scientific holism" (Chapter 5).

There is also an order of complexity. From "simple" to more complex, we find: physics, followed by biology, followed by sociology, with the arts closing the chain. "[T]he opposite journey from physics to end points, is extremely problematic. As the distance away from physics increases, the options allowed by the antecedent disciplines increase exponentially. Biology is almost unimaginably more complex than physics, and the arts equivalently more complex than biology. To stay on course all the way seems impossible. And worse, we cannot know before departure whether the complete journey we have imagined even exits" (Chapter 5).

"The profane word now having been spoken on hallowed ground, a quick disclaimer is in order. While it is true that science advances by reducing phenomena to their working elements -by dissecting brains into neurons, for example, and neurons into molecules- it does not aim to diminish the integrity of the whole. On the contrary, synthesis of the elements to re-create their original assembly is the other half of scientific procedure. In fact, it is the ultimate goal of science" (Chapter 10).

Such disclaimer should lessen the critics of reductionism. Reductionism is a fundamental stage that we need to go through to understand Nature. We have barely started to reconstruct the parts. Patience.