Friday, October 30, 2015

Neighborhood Effects, Ecological Causation, vs. Individuals a primary... in Sampson, The Great American City

 I have been reading Sampson's Great American City. The big theme in the book is "neighborhood effects," or ecological causation. He provides a very nice account of individual choice, suggesting as do many of the economic sociologists, that the individual and their choice-profile is emergent (not his term) from the neighborhood. Terms of art include social causality, spatial logic, self-selection bias (individual selection is a neighborhood effect), structural vs. individual. He is sensible and thoughtful, and surely worth a read for any doctoral student in any field in our School. Chapter 15 provides a summary of his argument in this arena.

It may be useful to keep in mind that at least in modern quantum field theory, individuals are emergent. Namely, quantum fields are primary (even if you "see" individual particles in those Feynman diagrams), and the appearance of discrete individuals is an emergent phenomena. Put different, and here Steven Weinberg's The First Three Minutes is particularly nice, as the universe cooled down from the Big Bang, the various individual particles we now see emerged, much as the orderly crystalline structure of ice emerges as you cool down water. In the Big Bang, where time is measured in terms of the exponent of the time after the Big Bang (10^seconds), where t is a negative number (for most of what interests Weinberg, and goes as high at maybe +2 in his book, but see next paragraph) and is that time, the earlier times are too hot for individuals to emerge and be comparatively stable objects. 

As for time, that t in that last paragraph, it takes some time, say when t is about +16 or 17, that is, billions of years, for the stars to form, supernovae to explode, the heavy elements to form. The universe is something like 13.8 billion years old, I believe, and so t is now about 17+.

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