Bar-YamChap8.pdf
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8.4.1 Human intuition—language and complexity The first method for estimation of complexity—the use of human intuition and language—is the least controlled/scientific method of obtaining an estimate of the complexity of a system. This approach,in its most basic form,is precisely what was asked in Question 8.2.1. We ask someone what they believe the complexity of the system is. It is assumed that the person we ask is somewhat knowledgeable about the system and also about the problem of describing systems. Even though it appears highly arbitrary, we should not dismiss this approach too readily because human beings are designed to understand complex systems. It could be argued that much of our development is directed toward enabling us to construct predictive models of various parts of the environment in which we live. The complexity of a system is directly related to the amount of study we need in order to master or predict the behavior of a system. It is not accidental that this is the fundamental objective of science—behavior prediction. We are quite used to using the word “complexity”in a qualitative manner and even in a comparative fashion—this is more complex or less complex than something else. What is missing is the quantitative definition. In order for someone to give a quantitative estimate of the complexity of a system,it is necessary to provide a definition of complexity that can be readily understood. One useful and intuitive definition of complexity is the amount of information necessary to describe the behavior of a system. The information can be quantified in terms of representations people are familiar with—the amount of text/the number of pages /the number of books. This can be sufficient to cause a person to build a rough mental model of the system description, which is much more sophisticated than many explicit representations that might be constructed. There is an inherent limitation in this approach mentioned more generally above—a human being cannot directly estimate the complexity of an organism of similar or greater complexity than a human being. In particular, we cannot use this approach directly to estimate the complexity of human beings. Thus we will focus on simpler animals first. For example, we could ask the question in the following way: How much text is necessary to describe the behavior of a frog? We might emphasize for clarification that we are not interested in comparative frogology, or molecular frogology. We are just interested in a description of the behavior of a frog. To gain additional confidence in this approach, we may go to the library and find descriptions that are provided in books. Superficially, we find that there are entire books devoted to a particular t ype of insect (mosquito, ant, butterfly), as there are books devoted to the tiger or the ape. However, there is a qualitative difference between these books. The books on insects are devoted to comparative descriptions, where various types of, e.g., mosquitoes, from around the world, their physiology, and/or their evolutionary history are described. Tens to hundreds of types are compared in a single book. Exceptional behaviors or examples are highlighted. The amount of text devoted to the behavior of a par ticular t ype of mosquito could be readily contained in less than a single chapter. On the other hand,a book devoted to tigers may describe only behavior (e.g., not physiology), and one devoted to apes
# 29412 Cust: AddisonWesley Au: Bar-Yam Title: Dynamics Complex Systems
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