Humanity made great progress in understanding reality by ignoring the overwhelming complexity of the universe, and focusing on small components of it in isolation from each other. Compare, for example, the ancient vision of the physical world of consisting of four elemental factors, earth, water, air and fire, to our understanding of the periodic table and the quantum mechanical factors beneath that today. We would not have got from the ancient view of the world to the modern without ignoring the overall complexity of the universe and focusing on individual components of it, in isolation from all others.
The success of this approach -- know as "reductionism' -- once lead to the belief that [....] more complex areas were merely simplified manifestations of the underlying fundamental determinants. For example, the biological processes in living organisms were thought to be merely a surface manifestation of the underlying chemical processes, and they in turn were just surface manifestations of the quantum mechanics that ruled chemical interactions. This attitude, know as "strong reductionism," argued that, ultimately all sciences could be reduced to physics.
In turn, strong reductionism implied that all large-scale systems could be understood by working up from the small-scale. In the case of economics, this implied that the behavior of the macro-economy should be derived directly from microeconomics [The method used today by neoclassical economics]
In the physical sciences a very different development occurred Poincare showed that there were limits to reductionism in 1899 [....] Reductionism still dominated the physical sciences for another seventy years, however, until these limits became apparent with the advent of the computer [....]
[T]he number-crunching power of computers enable researchers to considers systems with non-linear relations between variables [...] and they consistently observed a remarkable result; in systems where variables interact in non-linear ways, "the whole is more than the sum of its parts", and behaviors [emergent properties] will occur at the aggregate level that cannot be found at the level of the system's elementary components. [....]
Scientists then reconsidered the role of reductionism. It still had its place, but they were now aware of the fallacy in the belief that the best way to understand any systems was from the bottom up. [....The fallacy had two manifestation [....]
"The ability to reduce everything to simple laws does not imply the ability to start from those laws and reconstruct the universe. In fact, the more the elemental particle physicists tell us about the nature of the fundamental laws the less relevance they seem to have to the very real problems of the rest of science, much less to those of society
[~ Philip Anderson / More is different]
"The behavior of large and complex aggregates of elementary particles, it turns out, is not to be understood in terms of simple extrapolation of the properties of a few particles.Instead, at each level of complexity entirely new properties appear.
[~ Philip Anderson / More is different]
"Psychology is not applied biology, nor is biology applied chemistry"
[~ Philip Anderson / More is different]
The physical sciences embraced this discovery of emergent behavior, and what was first dubbed "chaos theory" and is now know as "complexity theory" is a fertile aspect of research in fields as diverse as physics and biology."
Steve Keen / Debunking Economics Ed.2 / p.205-208
