The revival of cities in medieval Europe: An application of catastrophe theory

In early medieval times, a great change came over Europe. One of its most noticeable aspects was the growth of cities which had been static or declining for centuries. This paper discusses the possibility that the growth was due to the fact that trade was gradually becoming easier. Using the notions of catastrophe theory, it is shown that even a slow improvement in communications could result in a sudden change in the nature of the system, with regions that had previously been unspecialized and self-contained changing over to active concentration on manufacturing or farming. The resulting improvement in living standard could explain the increase in total population which happened concurrently with the growth of the cities. A different explanation is also discussed: cities may have originally grown in response to the pressure of an independently increasing population. It is shown that in this case the growth patterns would be different, making it possible to test which of the two explanations is incorrect.