But even complex systems have an underlying mathematical logic to them. If there are more people that want to live in a place than there are places for those people to live, someone is going to lose that game of musical chairs. Seattle's Sightline Institute made this "Cruel Musical Chairs" video which starkly and powerfully illustrates the analogy.

If filtering is magical thinking, how is it any more magical than believing that if we stop adding more chairs, the rich—who could easily win the game of Housing Musical Chairs—will just walk away from it, leaving enough chairs (i.e. homes) for the rest of us?

3. Your City's Zoning Limits the Creation of Less-Expensive Housing

By limiting what can be built where, zoning and other land-use regulations may well restrict the total number of new homes in a given neighborhood, city, or even region to far fewer than the market would otherwise provide. Rick Jacobus, in this fantastic 2017 piece at Shelterforce, explains how this leads to the "luxury only" phenomenon by comparing developers to car manufacturers:

So no, the problem is not greed. The development industry is... behaving exactly the way we would expect any industry to respond to an artificial cap on their production volume. The same thing would happen in the auto industry: if we limited Toyota to only 100,000 cars per year, they might well choose to keep the Lexus and scrap the Camry, even though, at volume, the Camry is more profitable.

If land costs could be kept low—either by buying marginal, cheap land, or buying expensive urban land but distributing its cost over a large number of homes—developers might well find it profitable to build middle-income "Camry" housing at scale. But the first option, expansion on the suburban fringe, is fiscally ruinous for our communities, largely because of the colossal mismatch between the new public infrastructure those homes on the suburban will need and the tax actually generated by new suburban construction. And the second option, building more homes on the same amount of land, often can't happen because the zoning code says it can't.

One consequence of this is the proliferation of single-family teardowns in desirable urban neighborhoods. If the land is valuable, and all you can build on it is a single-family home, why not build a very expensive single-family home? Sightline has documented the spread of large homes in Portland that don't add any net new housing to the city, but were the most profitable thing developers were allowed to build on their lots.

This is why the proposal in Minneapolis's draft comprehensive plan to allow duplexes, triplexes, and fourplexes throughout residential neighborhoods is such a promising idea. Single-family homes in the city's toniest neighborhoods—particularly around the Chain of Lakes in its southwest corner—are already being torn down to build larger single-family homes. What if some of those were instead torn down to build triplexes or fourplexes?

These units would not be cheap, but they would be comparatively affordable, and this could have a fairly direct filtering effect. As people move into wealthy neighborhoods who might otherwise have lived in adjoining, more middle-class areas, there will be less competition for homes in those middle-class areas, and less upward price pressure.

To use the argument that newly constructed fourplexes will not be affordable to low-income residents as an argument against allowing them at all is entirely misguided.

4. Other Regulations are Driving up the Cost of Development

New development could be even cheaper if its costs were restricted to land and construction alone. But all sorts of other factors drive up the cost of development—and some of them are the result of well-meaning local regulations.

Many building codes, for example, require fire sprinklers in residential buildings. This is most common in apartment buildings, but California, Maryland, and Washington, D.C. require them in all homes. These requirements can add six figures to the cost of a project. Yet there is no epidemic of fire deaths in older buildings that are not equipped with state-of-the-art sprinkler systems. The sprinkler regulation, in isolation, is easy to defend on safety grounds; on the other hand, its cost, in the form of unbuilt housing that could have been, is harder to quantify and grapple with.