Some time ago, I wrote briefly about Jane Jacobs and her The Death and Life of Great American Cities. I found it in a list of recommendations from Andrew Gelman, which makes me want to go back and review the other books on his list that I haven't read.
I liked three things in particular about this book:
- her lessons about cities
- her detailed and interesting descriptions of her observations
- her very early use of ideas of complex adaptive systems
The first was simple: I had never really thought about the functions sidewalks and side streets play, and I had never thought about how a mix of uses during the day plays into keeping a city safe. I had not understood why some recommendations for urban renewal seemed to work so poorly nor what might be done about it. She made all that clear. I'll trust what she says, for I don't live in a city environment to be able to experience it first-hand.
The second was more important to me. Her book was, in a way, one long series of low-level observations, coupled closely with reasonable and reasoned inferences she would draw from those observations. She never got far away from the observations, so it seemed easy to verify her thinking. Using the ladder of abstraction metaphor, she seemed to stay on the lower rungs, and that made her thinking and her arguments more powerful.
The third surprised me. I didn't really expect an early 1960s book about city planning to dive into complexity theory, but she did it at the end of the book, after building up a remarkable story, and she did it in a way that was quite approachable. If you're curious, you can see an excerpt from "The kind of problem a city is," the last chapter of her book, at Katarxis No. 3.
If I took away lessons from this experience, they would include:
- Attend to outliers as well as central tendencies; attend to diversity as well as averages.
- Make sure inferences are based on observations, and make the chain to the observations as short and as transparent as reasonable.
- Explore new ideas and new theories, for some of them make help make better sense of observations. This admittedly may cause tension with the previous lesson.
- Be interesting, which comes in large measure from being interested.
I like to give links to other sources you can explore, but there are so many options in this case. P.J. Tayor published Jane Jacobs (1916-2006): An Appreciation in Environment and Planning A. Jacobs gave credit to Warren Weaver in her work on complexity; you can read the part of his work she references in The Rockefeller Annual Report, 1958 (start on page 23 of the PDF). I recommend this highly. If you liked Weaver's article and want to read more about making sense of complex situations in the social sciences, F.A. von Hayek's Nobel Memorial Lecture The Pretence of Knowledge might well belong on your reading list.
But, more than anything, read Jacob's The Death and Life of Great American Cities. It's worth it.