4
R. Camagni et al.
The main inspiration for most of the work of our research group originates from a
paper presented in 1984 at the Second World Congress of the RSAI (Camagni et al.
1986). This period was characterized by booming scientific creativity with groundbreaking works in fields such as the economics of urban size (Alonso 1971), city
systems and urban hierarchy (Beckmann 1958), spatial interaction models (Wilson
1970) and the associated dynamic versions (Harris and Wilson 1978), complex systems, mathematical ecology and self-organization modelling (Prigogine and Stengers
1984; Allen and Sanglier 1981). Camagni et al. (1986) is a theoretical and methodological work, although it has also been supported by empirical verification through
a computer simulation. In this work, all these traditionally separated research fields
were somewhat merged. Also, the paper added a crucial dimension, i.e. Schumpeterian innovation declined in spatial terms. The result was an eclectic, supply-side
self-organization model simulating the dynamics of an urban system (SOUDY).
The logical structure of the model paved the way for a few theoretical hypotheses
which, on the one hand, improved existing models and theories on urban structure
and growth, and, on the other hand, suggested new directions for further theoretical
advances and empirical validations. In what follows, we will deal with two major
fields of analysis in detail, using the SOUDY model as a guiding light.
2 On Optimal City Size
In the early 1970s, urban economics frequently dealt with the identification of an
optimal city size, whereby the distance between benefits and costs is maximized. In
particular, urban size optimality may be defined in terms of (i) minimum city size
(corresponding to the size at which average benefits begin to outvalue costs); (ii)
cost minimization (where, with benefits remaining constant, costs are minimized);
(iii) per capita optimal city size (i.e. city size associated to the maximum vertical
distance between average benefits and costs, usually interpreted as the optimal size
for dwellers); (iv) benefits maximization; (v) socially desirable optimal city size,
corresponding to the golden rule where marginal costs equal marginal benefits. This
condition is usually interpreted as the view of the rational national planner; and (vi)
maximum city size, corresponding to the largest city size whereby average costs
equal average benefits (Alonso 1971).
Yet, since the late 1970s research on optimal city size received relatively little
attention. Richardson first criticized the optimal city size theory, arguing that since
cities do not perform the same functions, they differ in terms of both costs and
benefits. This difference logically makes it impossible for cities to share the same
optimal size. Later on, Henderson (1985) questioned the validity of the optimal city
size theory, claiming that each city is characterized by a specific production function.
In fact, the same critique was also discussed by Alonso (1971), acknowledging that
an optimal size should be sought for each city. The logical consequence would be a
unique optimal city size for each individual city.
R. Camagni et al.
The main inspiration for most of the work of our research group originates from a
paper presented in 1984 at the Second World Congress of the RSAI (Camagni et al.
1986). This period was characterized by booming scientific creativity with groundbreaking works in fields such as the economics of urban size (Alonso 1971), city
systems and urban hierarchy (Beckmann 1958), spatial interaction models (Wilson
1970) and the associated dynamic versions (Harris and Wilson 1978), complex systems, mathematical ecology and self-organization modelling (Prigogine and Stengers
1984; Allen and Sanglier 1981). Camagni et al. (1986) is a theoretical and methodological work, although it has also been supported by empirical verification through
a computer simulation. In this work, all these traditionally separated research fields
were somewhat merged. Also, the paper added a crucial dimension, i.e. Schumpeterian innovation declined in spatial terms. The result was an eclectic, supply-side
self-organization model simulating the dynamics of an urban system (SOUDY).
The logical structure of the model paved the way for a few theoretical hypotheses
which, on the one hand, improved existing models and theories on urban structure
and growth, and, on the other hand, suggested new directions for further theoretical
advances and empirical validations. In what follows, we will deal with two major
fields of analysis in detail, using the SOUDY model as a guiding light.
2 On Optimal City Size
In the early 1970s, urban economics frequently dealt with the identification of an
optimal city size, whereby the distance between benefits and costs is maximized. In
particular, urban size optimality may be defined in terms of (i) minimum city size
(corresponding to the size at which average benefits begin to outvalue costs); (ii)
cost minimization (where, with benefits remaining constant, costs are minimized);
(iii) per capita optimal city size (i.e. city size associated to the maximum vertical
distance between average benefits and costs, usually interpreted as the optimal size
for dwellers); (iv) benefits maximization; (v) socially desirable optimal city size,
corresponding to the golden rule where marginal costs equal marginal benefits. This
condition is usually interpreted as the view of the rational national planner; and (vi)
maximum city size, corresponding to the largest city size whereby average costs
equal average benefits (Alonso 1971).
Yet, since the late 1970s research on optimal city size received relatively little
attention. Richardson first criticized the optimal city size theory, arguing that since
cities do not perform the same functions, they differ in terms of both costs and
benefits. This difference logically makes it impossible for cities to share the same
optimal size. Later on, Henderson (1985) questioned the validity of the optimal city
size theory, claiming that each city is characterized by a specific production function.
In fact, the same critique was also discussed by Alonso (1971), acknowledging that
an optimal size should be sought for each city. The logical consequence would be a
unique optimal city size for each individual city.