Does diversity mean everywhere has to be the same?

As I’ve discussed before, what proponents of this view don’t get is that while big cities provide greater diversity (and are rightly lauded for it), they also provide more opportunities for specialisation (see Are bigger cities less diverse?).

This is the key insight:

• You are more likely to find people who fit closely with your opinions, tastes and idiosyncrasies in a big city like Melbourne than in a smaller place like (say) Geelong…

• But the consequence is that once having found like-minded people, you’re also more likely to spend most of your time with them and ignore the lesser matches you’d tolerate in a smaller place.

Wellesley College researcher Angela Bahns and colleagues found students at smaller universities have a greater diversity of friends – in terms of lifestyles and opinions on issues such as abortion – than students at larger institutions. They subsequently compared big cities like New York with small ones like Iowa City and came up with similar results.

This is the “similarity-attraction effect”:

It influences everything from whom we date and hire to where we choose to live. The bigger the pond, the more likely we are—consciously or not—to swim around until we find a group of like and like-minded people.

Geographical concentrations of newly-arrived migrants are one manifestation of this effect at the aggregate level. So are families with children; they generally like to be near other families because there are benefits e.g. sharing child care, coordinating social activities around children. Singles like to co-locate too e.g. more opportunities to meet-up, fewer families objecting to noise.

In most cases this isn’t something to fear; it’s how the diversity dividend of big cities works – more diverse at the bigger scale but more specialised at the smaller scale.

The idea that all buildings, neighbourhoods or suburbs should have much the same demographic profile – that any significant deviation is a deficiency – misunderstands what humans want and how cities work to deliver benefits to their residents.

Cities are and always have been “spiky”; barring the invention of teleportation they always will be. That’s obvious in the lumpy way jobs are distributed spatially but it’s also true of other activities that benefit from co-location.

More singles and couples want to live in an apartment complex like the proposed Nylex development I discussed yesterday because they’re the ones who place the highest value on the benefits of the location and are more tolerant of the restrictions it necessarily imposes. Families with children mostly see better value elsewhere, perhaps a terrace or townhouse.

This clustering of like-minded people for mutual benefit (agglomeration economies!) is generally a good thing, but there’s one very important caveat; geographical concentrations of socio-economically disadvantaged residents are problematic because agglomeration can also amplify negative forces (see Does place matter for the life prospects of children?).

However there’s no compelling underlying logic or morality that legitimises planners trying to design in diversity of household types at the micro-scale in places like the inner city. And it’s of doubtful utility anyway; larger apartments in desirable locations are more expensive and mostly get taken by well-heeled singles and couples rather than families with children.

Planners would be better advised focussing on increasing opportunities for low to moderate income households of all types and sizes to gain access to affordable dwellings. One way to do that is to increase the supply of housing across the metropolitan area so that it matches demand.