D. C. Mikulecky

Professor of Physiology

Medical College of Virginia Commonwealth University


Why are complex systems different from simple mechanisms?

I submit that in the answer to this question is the essence of what we mean by complexity. The complex system possesses something that the machine or the simple mechanism does not. It is the truth or falseness of that assertion which is at the heart of complexity. If there is no "something" complexity becomes a synonym for complicated and we have nothing more to say.

On the other hand, it seems clear that the existence of that something is obvious. There is an ontology associated with the term "complexity".

If this is so, then there is a problem. One major response to these writings has been that the word "complexity" as used here, does not correspond to others usage of the word. That is the very point of all this! If this usage of the word is not what others mean by complexity, then what is the ontology behind the other meanings and how does this one differ?

The essence of the ontology of complexity is in the existence of something that is lost as the system is reduced to its parts. Otherwise, the whole is merely the sum of its parts, but the whole may be a more complicated arrangement of the parts. The idea complexity connotes is that when the whole exists; it is now the parts arranged in a more complicated way and this new arrangement gives rise to something real that the whole possesses.

I also assert that this can be formalized. Call this set of properties that arise out of the complicated arrangement functional components. These functional components only have meaning in the context of the whole system. Once they are "removed" from that context, they lose their meaning. In this sense, the functional components are a kind of semantics arising out of the syntax provided by the parts of the system. In this sense we have a nice analogy with language as a complex system.

This poses a challenge for anyone who wishes to say that complexity is something else. They would seem to need to establish a separate ontology and distinguish between what is being formalized here and their alternative. So far, none of the other notions of complexity have dealt with this. Until the "something" can be identified, I would wonder if they were not merely new forms of reductionist mechanisms that are so complicated that they need to be singled out. If that is what they are, why not call them complicated machines? If that is not what they are, then they must fall into the same category as what we are calling complex.


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