The best argument to be made for closing the notorious Rikers Island is that it’s hard to get to, isolated and thus a logistical problem for getting defendants to court as well as families visiting their loved ones. Of course, that was also its primary benefit, as it kept prisoners isolated. Not only was it harder to escape from an island, but it meant you didn’t have a jail next door.

Nobody wants a jail next door.

But the cries for closing Rikers have now reached the promise stage.

Mayor Bill de Blasio on Wednesday unveiled his long-awaited plan to close the troubled jail and open or expand slammers in four boroughs to house the extra inmates.

Gov. Andrew Cuomo quickly rushed out his own report warning that Rikers has become so violent under Hizzoner’s watch that the state may have to step in and speed up the shutdown — kicking off yet another round of sniping between the two rivals.

There is a disconnect in reasoning here that few seem to consider. If the problem is violence, then is closing Rikers the solution? Do the walls there beat people? Are the bars in Rikers cells more violent than the bars at the Tombs?

Rikers Island isn’t “toxic.” The system is replete with symbols of failure, but failure happens at the hands of those whose job it is to make the system work. Renaming Rikers for Browder wouldn’t save Kalief. Giving it back to the sea gulls won’t prevent kids held in jail for years for lack of the ability to make bail.

And this symbolic suggestion that closing Rikers will change anything is why nothing that matters ever changes. There are real problems, lots of real problems, and they won’t get fixed by pushing a fantasy.

But it’s a lot easier to pretend a physical plant is the problem than the actual problems are the problems. And so the scheme to close Rikers is now in full bloom. But if not Rikers, then where?

he city wants to build an entirely new jail on the site of the NYPD’s Bronx tow pound in Mott Haven, reopen the shuttered Queens Detention Center in Kew Gardens and expand still-operating Manhattan and Brooklyn detention centers.

“We can now move ahead with creating a borough-based jail system that’s smaller, safer and fairer,” de Blasio crowed, announcing that he has secured the support of key City Council members for the scheme.

Placing detained pre-trial defendants in facilities closer to home has its logistical benefits, although “safer and fairer” makes no sense at all. Jails are only as safe as the people running them make them. As for “fair,” the word has no relationship to jail under any circumstances. Mayor de Blasio is just testing to see if you’ll fall for the Nigerian 419 scam.

The four sites together will provide space for 5,000 more inmates, even though there are currently 9,000 prisoners on Rikers — but de Blasio claims he can reduce the population in the coming years through bail reform, quicker trials, lowering crime and reducing recidivism.

These are lofty goals, and achievable, although not by de Blasio, who persists in having his army bust turnstyle jumpers and pot smokers, prosecutors seek bail and criminal court judges rubber stamp needless numbers. If he could reduce the jail population, why isn’t he doing it now? For the same reason he won’t do it later. The PBA won’t love him enough.

Yet, there remains another aspect of this fantasy that is somehow lost in the mix. What of the correctional officers now working on the Rock? If it’s not the walls of Rikers that cause violence, might it be the guards who allow, if not foster, it? Is the plan that these same violent screws will suddenly turn into compassionate bowls of empathetic jello when reassigned to the new borough-based jails? Isn’t that how it works?

Certainly it’s not the guards who are responsible for violence, torture, in city jails. It’s the walls, the ceilings, the bars of Rikers. Get rid of the walls and everything will magically be better. If this doesn’t strike you as a sound belief, then what part of closing Rikers will fix the violence?

But there remains another issue surrounding this fantasy scheme. If Rikers is isolated, the tow pound in Mott Haven is outer Siberia. Yet, it’s a good choice for the same reason Rikers was a good choice. It’s far away from the nice people. Nice people don’t want jails near where they live, near their children. They don’t want nasty people in their neighborhoods. They don’t want the families of nasty people hanging out while they walk their kids to private schools.

Can you blame them? The property values will plummet. There will be the threat of crime, if not the reality, and certainly the unpleasantness of having to see, hear, be exposed to New York City’s riff raff.

And jail neighbors say they’re dreading the scandal-scarred lockup’s problems being outsourced to their neighborhoods.

“A man [on a corrections bus] once shouted some really vulgar language to me and my daughter. It was gross and unnerving,” said Boerum Hill mom Megan Marcy, 34, who lives near the Brooklyn complex.

“If expanding means more of that. I’m definitely not looking forward to it.”

But if not Rikers, where they are isolated on their own island, they have to be somewhere. And there’s nowhere in the City where people don’t live, and somebody will have to suffer the indignities of being around these “criminals.” So where?

For all its progressivism, the deeply passionate concern for social justice and tolerance of the downtrodden, why not a jail on Park Avenue? Maybe Sutton Place? Some of the fancy addresses, where the people who take limos to galas to support good causes reside.

If Mayor de Blasio or Governor Andy really want to make a dent in the problems they raise, build a jail on Park Avenue and wait for the cries to end cash bail, to stop the arrests of thousands of black kids for petty offenses that are only deemed a problem because Park Avenue matrons don’t want their windows broken. As I said, the lofty goals are achievable, but not without the will to make them happen. Put a jail on Park Avenue and watch the bold solutions take flight.