Jane Jacobs was a champion of the neighborhood and enemy of the car. In the last half of the twentieth century, highway systems literally sliced apart neighborhoods, diverted traffic around cities and away from downtown districts. City planning increasingly centered on cars, until Jacobs urged us to "look, listen, linger and think" in neighborhoods - in other words, to remember what we had forgotten while we were driving our cars: neighborhoods are pretty cool places to be.
Today's ecological pressures seem to be pressing for increasing density in cities, and taller buildings mean fewer neighborhoods. As I walk the streets of Toronto, I see the change all around me. Half a dozen such structures have sprung up within sight of the University of Toronto campus, each tearing down a medium-density neighborhood and replacing it with a twenty-story condominium.
"We are wedging ourselves between a rock and a hard place: between the pleasures of medium-density living (Greenwich Village, Park Slope, Toronto’s Annex) and the ecological necessity of even more density," explains Andrew Blum. He goes on to cite historian William Cronon: "idealizing a distant wilderness too often means not idealizing the environment in which we actually live." Blum's point is that "thinking of cities this way means seeing their density and grit not as the destruction of the environment but as part of its preservation."
The key is to bring together these two apparently discordant senses of "environment": the ecological and the social. Cities need to be proactive and encourage development of mixed-use structures that support inclusion in neighborhoods. I shouldn't think it difficult to reserve the first floor of a condominium for neighborhood shops--a baker, grocer, laundromat, pub, gym, or barber, all accessible from out of doors.
Related: maps of Toronto's high rises and an urban design contest called thinkToronto on spacing.ca.