Among the many viral videos that followed the attempted referendum in Catalonia, one of the most striking showed a hardened international footballer, Gerard Piqué, in tears before the cameras.

Piqué, who plays at centre-back for Barcelona and the Spanish national team, vigorously defended the right to vote; he recalled the dark years of the Franco dictatorship, and lamented the return of police brutality during the referendum. It was widely assumed that he voted in favour of an independent Catalonia. Yet within 48 hours, Piqué was training with the Spanish national team alongside his madridista – Real Madrid – team-mates. The apparent paradox was echoed in the chants directed against Piqué during training sessions, which – politely translated – informed him that “Spain is your nation” while telling him to “go back to your country”.

It is a paradox deeply embedded in Iberian history. In regions such as Catalonia, Galicia, and the Basque country, simultaneous and competing loyalties have often made for uneasy bedfellows (and team-mates). Spanish politicians invoke the word “democracy” with a frequency that suggests deep-rooted uncertainty about its longevity and stability. But Piqué’s call for dialogue suggests that these tensions could be contained and controlled. The independence movement, he claimed, was like the outburst of an 18-year-old threatening to leave home. “If you talk to him,” he suggested, “maybe he won’t leave.”

Piqué’s metaphor downplays the role of parents in provoking teenage outbursts. Back in 2010, in response to a case brought by the then-opposition People’s party, the Spanish constitutional court ruled many articles in the Catalan statute of autonomy unconstitutional. Yet in at least one respect he was right: the crisis has until recently fed on a desire for justice and self-assertion that is more widespread than the aspiration for a total rupture. This is reflected in the vacillations of the current Catalan leadership – President Carles Puigdemont, who speaks for a conservative nationalist base, has so far refrained from making a unilateral declaration of independence, holding his cards close to his chest in advance of Tuesday’s pivotal meeting of the Catalan parliament.

The court of international opinion is the only arena outside Catalonia in which Madrid is currently losing

Some members of the unwieldy nationalist coalition are holding out for independence. But the pugilistic posturing of nationalists on both sides has polarised a Catalan population that has been generally inclined to productive resolutions of political and economic grievances. The rise of Ada Colau, the Barcelona mayor who is closely allied to Pablo Iglesias and other leaders of the Podemos party, points to Catalans’ frustration at the brutal effects of the austerity policies pursued by corrupt oligarchies in Madrid and Barcelona after 2008, but also to their willingness to support a politician working within a national left movement.

“Escombrem-los!” (“Sweep them away!”) read the slogan on one pre-referendum poster, showing a Catalan woman brushing a panicked circus of cartoon villains into the Mediterranean: prime minister and former prime minister Mariano Rajoy and José Maria Aznar; King Felipe VI; Cardinal Antonio Cañizares; and a cluster of corrupt regional politicians. “Drain the swamp,” it might have read, if Barcelona were located on the same mythical terrain as Washington. But on neither side of the Atlantic is nationalism an effective response either to the immediate social crisis or its underlying problem: the emaciation of the welfare state and the precarious economic condition of the working class.

Any search for a resolution must start with the national dialogue that many prominent Catalans – and others – have called for. But this is unlikely to be generated spontaneously by the principal parties involved. Throughout the crisis, Rajoy has exacerbated tensions, forcing the hand of his Catalan opponents in what looks suspiciously like the pursuit of electoral advantage. Meanwhile, the signals sent by Saturday’s white-shirted, pro-dialogue demonstrations have been scrambled by protests in favour of national unity, culminating in yesterday’s massive anti-independence demonstration in Barcelona. While many of the unity demonstrators are motivated by high-minded ideals, the mobilisation of fierce nationalist sentiments has also awakened civic violence, and will take months, if not years, to reverse.

International intervention will therefore be critical in reducing tensions and stabilising Spain. The court of international opinion is the only arena outside Catalonia in which the government in Madrid is currently losing. Diplomatic pressure should be applied on Rajoy to recognise the Catalonian government as a legitimate interlocutor, and to move more decisively away from any semblance of adherence to a Francoist ideal of unity. Progressive forces in the Spanish Socialist party should be encouraged to speak out in favour of dialogue, and against the destabilisation of democracy in Spain by any party, including the central government.

Dialogue must go beyond the current binary debate. It should explore a variety of potential relationships between Catalonia and the central state government, and embrace the possibility of constitutional reform. It might contemplate a second referendum, requiring a two-thirds super-majority, to be held in late 2018.

Meanwhile, the Catalan and Spanish governments alike should lose no time in reversing the economic and social policies that have inflicted suffering on the Catalan working class. All parties must acknowledge that the brutalisation of civilian populations, whether through direct police action or even greater economic austerity, will further undermine Spanish democracy.

• Simon Doubleday is a professor of history at Hofstra University, in New York. He is the author of several books on Spanish history, including The Wise King