The Death and Life of Great American Cities (by Jane Jacobs) - 2
In the first part of this blurb/essay, I wrote briefly about some of the contributions that Jane Jacobs made to city/urban planning. She argued for diversity of use, short blocks, judicious planning to achieve the maximum diversity of use possible in a neighborhood. She detailed the complexity of city life, with each participant playing a part in what she labeled the ballet of neighborhood life and usage.
Thus her greatest contribution to urban planning, by far, was the emphasis on complex thinking. In other words: instead of considering each variable in turn as having an/one effect on each other variable, we should think instead of all variables not only influencing every other factor or variable, but that they a) change all the time b) influence every other variable and new ones we may not see, with the effect growing exponentially, the more variables they affect (which in turn introduce other variables, etc. An infinity helix, not just a double.)
A not-very-complex example of complex thinking follows.
Example: The Bright Company wishes to build a bank on 5th Ave. and 25th Street.
Simple One Variable Thinking: People will bank there.
Complex Thinking: There are already five banks in the neighborhood. They all open and close at the same hours. It might be better to house an all night cafe there because there are only three cafes in the adjoining ten blocks, and three of them close at nine. Thus there would be "eyes" on the street later at night, when the banks have shut down and most of the stores have closed. The neighborhood will be safer. This in turn will attract more people into the neighborhood and perhaps even during the day, making the neighborhood safer during that time period as well, and furnishing the population and density for, say, a new theater, which will in turn attract more business to inspire a new all-night restaurant and perhaps cause one of the cafes to stay open until midnight instead of nine.
In other words, Jane Jacobs actually understood the way cities work. They don't function in a vacuum. They function as living organisms which are receiving new cells and energy daily, hourly, by the minute, sloughing off old cells and creating new energies.