自己組織化論による都市群システムのモデルとその応用

システム概念の再定義

抄録

After the“quantitative revolution”of human geography in the 1950's, new concepts, such as the concepts of“system”, “model”, and“space”, were introduced into the field of human geography. The concepts of“model”and“space”were later reconceptualised by both humanistic and radical geographers, and it is important that these enriched concepts should be reintroduced into the field of quantitative geography. The concept of “system”, however, had not been properly reconsidered until the recent development of the“self-organization”viewpoint, which is formulated in the work of I. Prigogine (in his theory of“dissipative structure”) and H. Haken (in his discussion of“synergetics”).
The purpose of this paper is to review and evaluate models of interurban systems from the self-organization viewpoint. According to H. Couclelis, there are three kinds of systems: mechanistic, equilibratory, and evolutionary. A“self-organizing”system can be thought of as evolutional or as an internally regulated system, and has the following characteristics: it is an open system, it is influenced by both determinate and stochastic variables, it has multiple equilibrium states, it is influenced by non-linear feedbacks, and it follows its own local rationality. Undoubtedly, the introduction of these new concepts into the field of human geography will greatly expand geographers'“understanding”of the traditional frameworks.
The self-organization viewpoint has developed along with the trend of using a “mathematics of discontinuity”, which has focused on difficult problems such as chaos, catastrophes, fractals, and synergetics. Catastrophe theory, whose applications to human geography have been reviewed in the work of A. G. Wilson, attempts to explain sudden changes in a system's structure (of equilibrium) which result from gradual changes in certain conditions or parameters. Chaos theory focuses on unstable and unpredictable actions, such as oscillation, periodicity, and chaos, which result from non-linear, self-reflexive, determinate equations, and has been used in researching the instability of spatial systems. Fractal theory, which attempts to map out self-similar images, directly challenges the traditional Newtonian“mathematics of continuity”, and has been applied to the field of geographical morphology, including topography, meteorology, and urban morphology. The mathematics used in all three of these theories is extremely exploratory and pedagogical but is much more simple when used in the field of human geography. Synergetics, which is closely related to the self-organization viewpoint, is much more complex.
“Complexity”, however, implies not simply“complicatedness”but also an increasing degree of organization. Synergetics might also be thought of as the working out of the three competing and/or cooperating logics of non-linearity, reflexivity, and externality. P. M. Allen and M. Sanglier of the Brussel school, in applying the“self-organization” viewpoint, constructed an extremely complex model of urban systems. They considered the following socio-scientific issues:
(1) logistic growth of employment rates and residential populations;
(2) economic base and non-base activities;
(3) distance-decay attractiveness of central functions;
(4) internal and external economies.
These issues have been treated, to a greater or lesser extent, by several different models. The traditional Lowry-type urban model has treated the second and third of these issues, and has also considered feedback loops relating to urban processes. Most of the Lowry model's formulations, however, have been based on linear relationships.