Will New York City Mayor Bill de Blasio be able to reach across the affordability gap? Mario Tama/Getty Images

Behold the power of assonance!

The debate over a New York zoning deal that allows luxury developments to build separate entrances for the tenants in “market-rate” apartments and those in “affordable” units has garnered what is now weeks of coverage, despite a relative paucity of new events to push the narrative forward. The law, or variance in the law, such as it is, still stands. The buildings being built in this fashion are still being built. The number of new buildings going up with the same format, while likely noteworthy, has not really been noted.

But what the story does have is a really good bit of shorthand that captures the metaphysical reality of the physical realty; a concept, offensive on its own, that speaks to a broader offense; a metaphor poised to become metonymy.

What this story has is the “poor door.”

That is not meant as a criticism — not of the catch phrase nor its power. The practice, however — that’s a different story.

Now seemingly recognized as unpalatable by all but one-percenters, real estate developers and willfully ignorant contrarians, the poor door leads to a discussion of the bigger purpose of urban housing policy and the broader meaning of worth.

One can see the arguments, whether made crassly by developers who argue anyone who gets to live in a nice neighborhood at a discount price should jump for joy, or with more nuance by those who favor market-based approaches to the housing shortage: Separate entrances are part of the package of incentives — make that concessions — government extends to the private sector in exchange for needed units of affordable shelter, and it’s less bad than the alternatives.

The obvious alternative is no housing at all. The 55 rental apartments to be built behind the poor door at 40 Riverside Boulevard (the development that sparked the most recent debate) are 55 units, the argument goes, that otherwise would never exist.

But those units come at a price to the city, and only part of it is the consternation of most of its residents. The luxury high rise is substantially bigger than would have been allowed without the variance allotted in exchange for the affordable apartments. Developers also get a very healthy tax break for their beneficent troubles.

That’s not nothing — and as has been pointed out, the money lost in tax revenue to the city could pay for more than 55 units in a less tony part of town.

But that is the alternative that conjures up the foreboding image that hangs over all discussions of so-called affordable housing: The poverty-dense complexes of mid-century urban renewal — Cabrini-Green, Pruitt-Igoe, the Robert Taylor Homes — which represented a failure on multiple levels: