If the Sixers want to build a downtown arena, they and the city have to answer some questions first

Here is what we know about the plan, put forth by the 76ers’ managing partners, to build an NBA arena at 10th and Market Streets. We know that the partners are estimating, for now, that the arena will cost $1.3 billion to construct. We know that the partners are promising, for now, to fund its construction without any city dollars. We know that the plan calls for the arena to be completed by 2031, the same year that the Sixers’ lease with the Wells Fargo Center expires.

» READ MORE: Sixers fans, players and local residents react to proposed $1.3 billion arena in Philly’s Center City

Here is what we don’t know: We don’t know what we don’t know. The arena, theoretically, would open nine years from now. Nine years is a long time. The Sixers, the city, the country, and the world will change in profound ways over that period, and right now, we have absolutely no idea how.

Go back nine years, to 2013. How many people, when asked to name the person who would most affect our political life and discourse over the subsequent decade, would have said Donald Trump? How many, when asked what sort of event might cause the most damage and upheaval to our fragile global balance, would have said they were most fearful of a novel virus? Take an example that’s less significant but more to the point: In 2013, how many Philadelphians even knew who Joel Embiid was? Today, he’s the primary reason the Sixers are popular enough that they might consider building their own basketball palace.

Anyone who likes the idea of a downtown arena is probably picturing the city as it is now and the Sixers as they are now: a team with a superstar in Embiid, a budding star with an endearing personality in Tyrese Maxey, and a chance, if everything goes right, to win a championship — a team that draws and holds the interest of a wide swath of people in the region. That same description would have fit another franchise back in 2013: the Flyers. And remember: 2031 is just the year that the arena is supposed to open. By then, Maxey will be turning 31. Embiid is unlikely to be on the roster anymore. And Bronny James may already be wearing an NBA championship ring or two on his hand.

The critic and author Chuck Klosterman gets at the heart of this idea in But What If We’re Wrong? It’s a smart book that suggests we ought to be more intellectually humble about the predictions we make. “When you gaze into the haze of tomorrow,” Klosterman writes, “everything is an assumption.” We try to envision the future based on the present, and that exercise is inherently fraught. We’re bound to be wrong. Crime in Philly is bad now, so don’t build the arena and Crime in Philly is bad now, but the arena will make things better and safer are opposite sides of the same coin of mystery and uncertainty.

» READ MORE: If Sixers leave Wells Fargo Center for new arena, Philly will be an outlier among sports towns

The status quo won’t last. It never does, and we’re kidding ourselves if we think we know how it will change. All we can do is ask the questions that seem most pertinent and relevant in the here and now. So let’s ask a few of them, and let’s hope the Sixers’ leadership, the city’s leadership, and the city’s residents are asking them, too.

In their previous arena/development proposal, at Penn’s Landing, the Sixers also said they would not use any city or state funding. But they did ask for $700 million in tax breaks. Under this new plan — as author Neil deMause already has raised — will managing partner Josh Harris and his team pay their full share of wage, property, and sales taxes?

What is the counterevidence that the Sixers might offer to the preponderance of research and literature that shows there’s little to no economic benefit to municipalities from building stadiums and arenas? Why should anyone think this trend will have reversed itself by 2031?

The rise of remote work allows more people more freedom to live anywhere they choose; they’re no longer necessarily yoked to a certain neighborhood or region because of a morning commute. So how populated will Philadelphia be in 2031 and beyond? Will the Fashion District necessarily be a thriving hub of restaurants, bars, businesses, and foot traffic?

Will an arena at 10th and Market be as accessible to suburban Sixers fans — and suburban Sixers fans’ dollars — as the Wells Fargo Center and the rest of the South Philadelphia stadium complex are?

» READ MORE: The Sixers aren’t the first team to eye Center City. Here’s why it didn’t work for the Phillies.

When the Eagles built Lincoln Financial Field, they decided not to equip it with any kind of dome or roof. They considered it too costly an investment, and as team president Don Smolenski told me in February 2018, they were fearful of public criticism “for making it ‘too corporate’ to be for Philadelphia.” But as an open-air stadium in the sometimes-frigid, sometimes-sweltering Northeast, the Linc is limited in the non-Eagles events it can accommodate. It would be stunning, for instance, for Philadelphia to host a Super Bowl. What features would keep the Sixers’ new arena fresh and versatile and prevent it from lapsing into obsolescence 10 years after it opens? Twenty years? Thirty?

Nine years ago, the Sixers were a lousy team, and they were about to embark on The Process, which would ensure they would remain a lousy team for another several years. What if, come 2031, they’re lousy again? How many Philadelphians and basketball fans will be so eager and excited to open a new arena then?

» READ MORE: Chinatown coalition calls Sixers arena proposal a threat to their neighborhood’s identity