The people of Berlin love an argument. They also, at least since the Berlin Airlift, feel very strongly about their airports. So it's no surprise that the popular referendum on Germany's September 24 national election day about whether Tegel Airport should stay open has become the focus of heated attention as a comparatively tepid campaign for the chancellery draws to a close.

The referendum is non-binding because it doesn't task Berliners with voting on a specific proposed law. Instead, denizens of the capital are being asked whether to "demand that the Berlin Senate give up its closure intentions and take all measures necessary to ensure the indefinite operation of the airport."

The referendum has divided the city. Many residents appreciate the relatively central convenience of Tegel, which has served as the Berlin's main airport since the late 1960s, and fear that the new Berlin-Brandenburg Airport, which is years behind schedule and billions of euros over budget, won't be adequate for needs of Germany's largest city. Those who live near Tegel and environmental activists say that the agreement to close the airport as soon as Berlin-Brandenburg, known as BER, is operational is already a done deal and that the idea of a major airport in the middle of an urban area is outmoded.

Political parties have adopted Tegel as a centerpiece of their campaigns. The small-government, business-friendly Free Democrats (FDP) used the issue as a springboard to get back into the city's parliament in local elections last year and are pushing it hard again, while the Greens are heading the charge against the airport.

A dead horse or costly replications?

The pro-Tegel fraction, which is leading in the public opinion polls with 55 percent support, is portraying the referendum as a chance for the electorate to correct a mistake made by the city's Social Democratic-Green-Left Party coalition government. The FDP argues that BER, which was planned more than a decade ago, is too small because original projections about Berlin's growth as a metropolis and tourist magnet were far too pessimistic. Ordinary citizens, they say, know better.

"People in Berlin are lot more pragmatic than the governing parties, which first need to get down off the dead horse that is the one-airport concept," Helmut Metzner, the operative manager of the FDP's Berlin chapter, told DW.

The pro-Tegel fraction also contends that having more than one airport would offer the German capital extra flexibility in case of severe weather damage, terrorist attacks or similar disruptions. That's "nonsense," Berlin's Green party chairman Werner Graf told DW, pointing out that "you can't land in two airports at once."

The anti-Tegel faction says that a single airport strategy is more economical.

"Maintaining multiple airports also costs money," Graf says. "You need two fire stations, two towers, twice as many air traffic controllers and a lot more personnel."

The other main argument for closing Tegel is to spare the nerves of the 300,000 people who live in the vicinity.

"These people have to put up with 500 flights every day and 185,000 starts and landings every year," Graf says. "In all the other cities you might fly to - Munich, Paris or London - the city airports are further away than BER will be."

Referenda concrete and general

Amidst the debate over Tegel Airport itself is another argument about the role played by direct-democratic referenda within Berlin and Germany's representative-democratic parliamentary system. Tegel opponents claim that this referendum will have no teeth because even if the yes vote wins, there are no legal and legislative mechanisms to overturn the shut-down of the airport.

"I have nothing at all against letting the people have their say," Graf says. "The question is whether you're taking people for a ride or doing it seriously. Ultimately, the issue isn't this simple. If people decide something it has to be concrete. That's not the case with the Tegel referendum."

The pro-Tegel side acknowledges that Sunday's vote is non-binding but says that an expression of popular preference will be useful.

"A strong yes vote with, say, 800,000 supporters would be a signal to the city government, which itself only got around 800,000 votes in the last local election," Metzner says. "They may imagine themselves as heroes, but they're probably not heroic enough to ignore such a strong vote by citizens. You can't withstand that politically."

Are popular referenda inherently populist?

Popular referenda are generally only permitted in Germany at the state level. But there is a vigorous movement calling for direct democracy at the national level as well.

Indeed, all of Germany's major political parties except Angela's Merkel's conservative Christian Democrats (CDU) support the idea of national popular referenda. The far-right populist Alternative for Germany (AfD) even features it prominently in its party platform, and its Berlin chapter, like the FDP, supports keeping Tegel open.

But Oliver Wiedmann, spokesman for the direct-democracy advocacy group Mehr Demokratie, says that when it comes to the Tegel referendum, local authorities, who have a reputation for being error-prone when it comes to airports, didn't handle the issue well.

"What went a bit wrong was that the legal question of whether the referendum can even be put into practice should have been settled at the start," Wiedmann told DW. "It's an unsatisfactory situation for voters. Can it be put into practice or not? No one knows. If it isn't, the result will be frustration and that will negatively reflect on the instrument [of popular referenda] itself."