This year marks the 60th anniversary of the signing of the Treaty of Rome, the foundation stone of the European Union. In those first years of post-war Europe, political leaders shared a vision of a unified continent built on a shared set of liberal values of tolerance, inclusion and integration, and a drive never to return to the inward-looking nationalism that created so much bloodshed on the European continent.

This expansive vision of the EU’s founders is at risk today. Europe is seeing a return of populist nationalism and a strengthening of narrow, exclusionary identities. This has manifested itself in anti-immigrant sentiments and in direct repudiations of EU integration such as Brexit, the UK vote to leave the union. The failing of the original vision risks fragmenting the continent once again, returning to the borders and barriers of the past.

In many ways, this wave of anti-EU and nationalist sentiments stems from a lack of a strong common European identity. The push in the UK to leave the EU arose because many British people do not feel European; they did not feel they shared a common identity with the Poles and Romanians who came to work in their country. The inability to promote social integration alongside political integration has been perhaps the greatest failing of the European project.

It is important that strengthening European identity does not require abandoning national identity, which is a central part of many people’s sense of self, any more than identifying with a national polity requires giving up local sources of identity. Greater European cohesion does not come at the expense of weakening nation states, but rather strengthens them, by giving them more power to act together on the world stage.

Promoting European identity is challenging for a number of reasons. Creating a shared sense of identity on a continent with a multitude of different languages poses significant practical problems. Europe as a whole is also a religiously and culturally diverse region. These challenges also have the potential, however, to be Europe’s greatest sources of strength. By accommodating and incorporating diversity, any European identity must of necessity be inclusive and expansive; it must be cosmopolitan, repudiating xenophobia and celebrating difference. A robust sense of European identity would undoubtedly have helped in how European countries handle the integration of migrants.

What, then, does a European identity consist in? This is a difficult question: too nebulous a definition risks the charge that being European means standing for nothing in particular. Many people have attempted to promote European identity through a shared philosophical, artistic and scientific tradition on the continent. This is largely the strategy of the EU itself, which chose Beethoven’s Ode to Joy as its anthem and which celebrates figures Leonardo da Vinci, Desiderius Erasmus, and John Locke as heroes of a shared European heritage. It is a shared heritage in these thinkers and creators, and a shared belief in their values, that makes us European.

But while this idea is commendable, this attempt to ground identity in “high” culture lacks popular resonance, making European identity seem instead to be something elitist and exclusionary. This ideal of European identity needs to be augmented by a popular source of European identity. Such popular expressions of European identity already exist, albeit to a very limited extent: The Eurovision Song Contest and the UEFA Champion’s League soccer tournament are two annual examples where people from different countries come together (and compete) under a shared sense of being European.

The signatories to the Treaty of Rome had witnessed a Europe ravaged by deprivation, war and genocide. They envisaged a future where people all over the continent would stand together under a shared sense of being European, and where the prospect of war in Europe was unthinkable. This vision now seems dangerously fragile. The barriers to a common European identity need to be removed, so that we can ensure peace and security for all people on the continent.