What links the results of the Catalonia elections last week with the row in Britain over the proposed new blue passport? The one is the latest expression of the polarised character of electorates, the other of the way that the most arbitrary, irrelevant issues can become the focus of intense political controversy. Neither polarisation nor conflicts over arbitrary issues is new. But both have become defining features of our times.

Nations today seem divided down the middle on critical issues – whether Catalonia over independence, Britain over Brexit or America over Donald Trump. This is not just a western phenomenon. A week ago, Cyril Ramaphosa won the election for the ANC leadership by the narrowest of margins – 2,440 votes to his opponent Nkosazana Dlamini-Zuma’s 2,261. Earlier this year, the referendum called by the Turkish president, Recep Tayyip Erdoğan, to extend his powers approved the measures by 51% to 49%. Every electorate seems divided and uncertain.

Many see in such polarised nations societies that no longer possess a sense of common values and so have little material with which to bind themselves together. The consequences, many fear, are more unstable societies with governments that lack authority among large sections of the electorate and a political system open to exploitation by extremists, especially far-right extremists.

From a historical perspective, though, contemporary polarisation does not seem particularly acute. Go back a generation. Is Britain more polarised now than it was in 1984, at the height of the miners’ strike? Today, newspapers might describe judges, of whose decisions they disapprove, as “enemies of the people”. Then, it was government ministers who called striking miners “the enemy within”. The full force of the state – from the police to propaganda – was mobilised to crush the strike, leading to mass invasions of mining communities, bloody confrontations, as at Orgreave, tens of thousands arrested and a Britain far more divided and embittered than it is today.

Or, as fractious as America is today under Trump, is the nation more divided than it was in the mid-1960s, when its major cities were in flames as black protesters confronted a deeply racist state, and when anti-Vietnam protests so inflamed the authorities that National Guardsmen gunned down student protesters at Kent State University?

It is a myth to imagine that societies in the past had an undisputed vision of the common good that bound them together. Societies have always been fractured and fractious and values always contested. What is different today lies not in the way we look at our commonalities, but in the way we look upon our differences.

Politics is, by definition, divisive. It divides society along ideological grounds and demands that people take sides on fundamental issues. In the past, the political divisions by which people made sense of the world, and positioned themselves in it, were defined primarily by left and right. Today, as the left/right divide has eroded, so political frameworks are often shaped less by ideology than by identity. People find their place in the world today less through categories such as “liberal” or “conservative” or “socialist” or “communist” than ones such as “Scottish” or “European” or “Muslim” or “white”. Even when people talk of being “liberal” or “conservative”, or a “Brexiter” or “Remainer”, they are often talking as much of cultural identities as of political viewpoints.

The shallowness of political debate and attachments means both that almost anything can become “political” and that almost nothing is. The most trivial of matters – the colour of one’s passport – can suddenly seem ideologically significant, while politically profound issues – the meaning of sovereignty, for instance, and how it is best expressed – are barely touched upon in public. Symbolism has become almost as important as policy. This lends to contemporary politics an almost arbitrary character.

It was the case that old-style political attachments to left and right were often tribal in form. I might vote Labour because my family always had or because that’s what one did round here. But such tribalism was not arbitrary and meaningless. The left/right divide expressed fundamentally different views of the world and of attitudes to issues such as inequality or trade union power. Tribalism was given meaning by these wider political attachments.

Today, in the absence of wider social struggles or political attachments, tribalism has become an end in itself. Labels such as Remainer or Brexiter are less a means of linking oneself to wider struggles than of hunkering down and refusing to engage. Why bother engaging when, for many Brexiters, Remainers are unpatriotic, even traitors, and enemies of the people, while, for many Remainers, Brexiters are uneducated, bigoted, xenophobes?

Politics may be divisive. But it rests also upon a willingness to have a public dialogue and debate, a readiness both to listen to others and to scrutinise our beliefs, an openness to accommodate others and to change ourselves. It is such willingness and readiness and openness that has faded in recent years.

The very idea of politics as an act of deliberation, by which people with different desires and starting positions must work something out, has become devalued. There are, naturally, limits to political deliberation. Politics is about contesting power and there are times when the contradictions between the political visions embodied by different ideologies cannot be deliberated away but have to be confronted directly. So it was with the miners’ strike. The Thatcher government sought confrontation with the miners because it recognised trade union power as an obstacle to its economic and social policies. The miners confronted Thatcher’s pit-closure programme because it spoke to a larger attack on working-class communities that needed resisting. The eventual defeat of the miners, and of other trade union struggles, opened the way for a much more aggressively atomised society that helped snap social bonds and hollow out civic life.

Social struggles are not only about confronting power, but a means of shaping values and ideals. Such struggles enable people to reach out beyond their own identities and give meaning to civic solidarity. It is through such social struggles that we can define what common goals or common values should be. Without such struggles, we can neither work through differences nor shape what we hold in common.

Social divides today seem more intractable because they have become disconnected from social movements. Symbolism has come to take the place of real change. And there is the irony: it is not that societies are too polarised, but that they are not polarised enough. Societies have become divided, but without the possibility of real social change.