Two major concepts define the political struggle in the west today. One can be termed “globalism”, which is currently most prominently represented by the German chancellor, Angela Merkel. The other is “territorialism”, a view that the very likely Republican candidate for the US elections in November, Donald Trump, represents.

At the core of the debate is the meaning of borders: should they be porous or tightly controlled? Are they mainly an obstacle to the free and productive flow of ideas, people, goods and information and should therefore be largely dismantled? Or are massive borders welcome and indispensable as a protection against all kinds of real or perceived threats such as competition and terrorism?

For globalists such as Merkel, interconnectedness is a good thing because it is what drives progress towards more prosperity and freedom everywhere. For territorialists such as Trump, interconnectedness is mainly a threat. What is good and healthy is attributed to the natives and what is dangerous comes from outside: unfair Chinese competition, dangerous Mexican immigrants and Middle Eastern terrorists.

Globalists want to manage the cross-border streams and minimise the disruptive character of borders to maximise the gains from connected markets and societies. Of course those streams have to be managed and this is why governance cannot any more be limited to the national territory. Governments need to co-operate and set up regional and global institutions; they need to set rules and make sure that these rules are upheld. Globalists argue among themselves about how to police the wider spaces but not about the principle.

Territorialists, by contrast, don’t believe in international and transnational institutions – they believe in national strength and power. Donald Trump wants to invest in the US military so that it’s “so big and strong and so great” that “nobody’s going to mess with us”. The world outside the borders is anarchical and dangerous and the way to deal with threats is to fight them by using force. “Bomb the shit out of Isis,” Trump said. Allies are not an asset, they are a burden because they are free riders, cheating on America’s taxpayers: “We can no longer defend all of these countries,” he said, citing Japan, South Korea and Germany.

The man who may be the next US president also proposed closing off parts of the internet so terrorists could not use to recruit. The territorialist’s answer to the abuse of freedom and openness is to use force abroad and to disrupt the flow of people or information. Trump wants to build “the greatest wall that you’ve ever seen” on the US-Mexican border, to keep illegal immigrants out.

Territorialists believe they can prosper economically even while interrupting, diminishing and shutting cross-border flows. Jobs must be brought back, free trade agreement renegotiated because they are unfair to Americans. US companies such as Ford must be punished for investing abroad. Apple should build its “damned computers” in the US and not in China. Countries such as China, Japan, Mexico, Vietnam and India are “ripping us off” and need to be punished.

Trump is, rhetorically, the most aggressive politician of this sort, but he’s far from alone. US commentators have blamed the Republican party for capitulating to populists for years, allowing Trump to harvest what others have planted. And Europe has its own share of territorialists, who share many of Trump’s views. Marine Le Pen in France, leader of the Front National, stands a good chance of winning the first round of next year’s French presidential elections. Then there’s Viktor Orban, prime minister of Hungary, who rose to international prominence by making the case for “illiberal democracy” and for his determination to respond to the refugee crisis solely by building massive fences. Territorialism is a form of populism: simple, inconsistent answers to complex challenges, based on the politics of fear. Territorialists divide the world into friends and foes; they attribute everything positive to the natives and everything negative to those beyond the borders.

But the biggest problem with territorialism is not polarisation, it is that the concept is deeply flawed. Territorialists suggest that people can have their cake and eat it: disrupt globalisation and stay rich, minimise investment in international affairs and alliances and remain safe and free. They take the huge gains in prosperity, security and freedom of the last decades for granted. They fail to understand that those gains depend on massive investments of nation states in international order, and that globalisation is based on open societies and increasingly easy cross-border flows of goods, people and information. In other words, if territorialism wins, globalisation is under threat.

Merkel thinks we are indeed at a crossroads; the refugee crisis is part of a larger challenge that she describes as “our rendezvous with globalisation”. For her, the key challenge is how to keep globalisation afloat in spite of increasing geopolitical conflicts and tensions. Merkel is one of the few western leaders who has lived in a country that was unfree, poor and isolated from the west by a wall and fences secured by mines. She was 35 years old when the Berlin Wall fell in 1989. She knows what it means to be shut off from global flows, locked in a country by an insurmountable border. For Merkel, globalisation equals progress. Open spaces and increased interaction across borders are a good thing, as they unleash opportunity and secure freedom and prosperity at home. Globalisation is challenging, but on balance the gains are much bigger than the risks. Also, in a world of large economic regions such as the US and China, the space in which German politics operates cannot be limited to the German territory any more.

Open borders in Europe are “deeply in our interest”, she argues; no other country gains from those achievements “more than us” and needs them more “because of our geographical location”. But responsibilty goes beyond the shared European space: “In an open world we also have to take on more responsibility for what happens outside our European borders.” Open borders in Europe are under threat. The refugee crisis, driven by the war in Syria, is testing the Schengen system that was set up in 1995. It is unclear whether the system is going to survive this stress test and what a revival of borders means for the EU.

Governments are torn between the desire to protect the joint space created by European integration and the pressure from territorialist forces whose narrative often dominates the debate. If they want to retain the achievements of globalisation, centrist forces need to start pushing back. They need to start making a much stronger case for open borders and open societies.

Ulrich Speck is senior fellow at the Transatlantic Academy, Washington DC