(Top photo: @Nigel_Farage / Twitter)

Them and Us; Us and Them. How do you define an "Us" and how do you relate to a "Them"? Here lies the whole of politics.

Beneath all the apparently cold-light-of-day rational deliberations people convince themselves they make over this or that policy, this or that pledge, politics primarily concerns relation to groups: groups that have different structures, goals and lifespans, different norms of codified and policed behaviour, different scope for transformation from within, different modes of relating to outsiders. It is your "Us" – however that's defined – that you believe is the driving force for the actions of your political representatives, the entity they are (supposed to be) serving. And it's these often unconscious dynamics of group belonging that feed – and are in turn fed by – the fantasy life and imagined coherence of groups, wherever they fall on the political spectrum: all degrees of conservative, all shades of the liberal-left.

Us and Them. Rarely has the political atmosphere seemed so acrimonious, so adversarial, but then nothing divides quite like a referendum: Yes or No, In or Out, Them or Us. If the aftermath of the Brexit vote wasn't enough to illustrate the prevailing political polarisation of left and right, then each week the Trump phenomenon jimmies open America's bitter division a little further.

Beyond the social media echo chambers, public airwaves have become hard-edged and feverish. Compassion is stigmatised as "virtue signalling" by conflict-addicted agitators, while taking offence at the gleeful shit-stirring of these deeply miserable contrarians makes you an oversensitive "snowflake". Listen to the misanthropic Katie Hopkins, or the dead-eyed self-confessed sociopath Milo Yiannopoulos, and you realise that for these people happiness is a zero-sum game: triggering "lefties" is the only way a tiny droplet of serotonin can find its way along those dusty neural pathways.

But that's where we're at, so distant from rapprochement that the idea has been floated in some corners – and not entirely in jest – that we turn our uneasy post-Brexit togetherness into fully-fledged separation. Ideological apartheid. And while there may be one or two tiny logistical problems with such a solution, the idea does nevertheless provoke an interesting thought-experiment: what would happen if Brexiteers and Remainers – or GOP conservatives and liberals, for that matter – got divorced? Which community – right-wing or left, to partition them overly schematically – would be more content in their respective "utopia"?

Or perhaps the division isn't so schematic. Perhaps the segregation has always existed – the left from Mars, the right from Venus – shaping or prompting our opinions and values before we're even aware that they're "ours'" At least, that's the premise of a growing body of research in the fields of political psychology, neuroscience and evolutionary anthropology, which suggests there may be – not quite irreconcilable differences, but certainly a biological basis for the divergent political outlooks of right and left-wingers.

A 2003 paper from the journal Psychological Bulletin, "Political Conservatism as Motivated Social Cognition", claims that the key personality variable predicting political conservatism was death anxiety. A more recent paper by political scientists at the University of Nebraska, since expanded into a book, was able to demonstrate, using eye-tracking technology and devices measuring skin conductance (sweating as a sign of physiological and psychological arousal), that conservatives have a much greater focus than liberals on negative stimuli, or a "negativity bias". Confronted by emotively varied photo collages, conservatives locked more quickly and dwelled for longer on threatening or disgusting "aversive" images (faeces, spiders, gaping wounds). Liberals, by contrast, were drawn to "appetitive" images (bunnies, smiling kids, sunsets). Tomayto, tomahta.

"The emotional tenor of right-wing causes exerts a stronger immediate pull, the alarmist headlines of the Mail and Express speaking less to the brain's reasoning centres than shouting at the ancient, reptilian brain."

What's telling here is that despite their aversive physiological responses, right-wingers still devote more time and attention toward the object of their disgust. It thus follows that their inflexibility toward people who deviate from "norms" (gays, minority races and religions, atypical gender roles) is expressed with such fervour because they are obsessively intolerant of things they find divergent and objectionable. They fixate.

French philosophers Gilles Deleuze and Félix Guattari coined a novel term for how this fixation on threats and anxiety-provoking negative stimuli drives the dynamics of group-formation and shapes perception. They called it "fascism-paranoia" (where paranoia is to the psyche as fascism is to politics). The constant sense of being assailed by dangerous or persecuting agents from outside the group goes hand in heterosexual hand with the obsessive monitoring of who forms part of the "Us", and what they get up to. It's both hyper-vigilant and thoroughly prescriptive, an active process of enforcing conformity to an identity ideal – "this is what a 'true Muslim' or 'true Christian' does"; "this is what being British is" – rather than finding those supposedly inherent traits in the flesh. It's a making-the-same. And difference or deviation flickers on the purified identity grid as threat.

Of course, there's an evolutionary explanation for conservatives' heightened awareness of – and obsessive vigilance for – threat: it keeps the tribe safe, not only from predators and rivals, but also disease. However, as anthropologist Avi Tuschman argues, this breeding strategy (turned political disposition) is also disadvantageous, inasmuch as it also prevents new proteins entering the gene pool. And yet, if "appetitive" liberalism correlates to a more "advanced" evolutionary strategy, why is "aversive" right-wing populism on the march? The answer – beyond the perception of existential threat – is that this political struggle isn't symmetrical.

First, consider, schematically, the two groups' general nature. Left-wing groups are situational, often based on social class (which can in theory change) or adherence to causes. They are mortal, provisional, finite and inclusive, since membership is an act of choice not an accident of birth. Right-wing groups derive more from (supposedly) essential, non-negotiable, "eternal" or "immortal" identity categories – race, nation, creed – that are inherently exclusive.

Second, consider the primary emotions and values driving these groups: on the left, convivial outreach building toward "social justice". On the right, suspicion of threat leading to continually renewed order and security. Bridges and walls. The emotional tenor of right-wing causes exerts a stronger immediate pull, the alarmist headlines of the Mail and Express speaking less to the brain's reasoning centres than shouting at the ancient, reptilian brain. It takes years to build trust and solidarity, moments to destroy it.

Some antifascists attacking a fascist in Brighton (Photo: Henry Langston)

The resurgence of nationalism epitomises how these asymmetries provide a perennial obstacle for the left. Take Brexit. The allure of the facile, anxiety-quelling slogan "Take Back Control" had no equivalent on the Remain side ("They may be neoliberal technocrats, but reform is better than retreat" couldn't fit on the bus). The left struggles to mobilise code-red emotions. For Leave, Brussels (and immigration) was the threat, patriotism the palliative. For Remain, working-class nationalism is tantamount to acting against what your objective, rational class interests ought to lead you to do. It suggests you'd rather live under bad laws made by your fellow countrymen than good laws made by foreigners.

Nevertheless, the main problem with fascism-paranoia's heavy-handed imposition of internal order, so as to ward off threats and reduce anxiety – and here is the crux of our thought-experiment – is that it doesn't actually reduce anxiety at all. It generates more of it. For the more you huddle together under an abstract identity banner – the more you patrol the borders and enforce the obedient embodiment of that identity – the more you will inevitably see danger and deviation everywhere. It's contagious. And it creates ever decreasing circles of trust.

First, the "Us" is "Americans". But who's truly American? So "Us" becomes "Christian Americans". But that includes blacks, so it's "White Christian Americans". But that maybe includes the globalist libtard traitors. Eventually you withdraw further, and the Enemy becomes the neighbouring state – "Fuck Michigan!" says an American patriot in Ohio – then the next city, the next suburb... It's permanent psychic war.

Of course, the irony is that while the left are characterised as timorous snowflakes, right-wing behaviour is largely conditioned by insecurity, much of which derives from the convulsive late-capitalist transformation of traditional social roles – be that through post-industrialisation, or through feminism enabling women to bypass male "ownership" of their reproductive organs, which Tuschman suggests is the prime motivation for the conservative propensity to create homogenous groups.

Can the right ever be truly happy? Anecdotal evidence suggests not, for on the day Parliament voted to trigger Article 50 – the day his life's work was effectively secured – Nigel Farage tweeted a list of the 114 MPs who voted against, saying they were "enemies of democracy". And the further right on the political spectrum you go, the greater the compulsion to find something to rail against (the most versatile of all these bogeymen being "cultural Marxism").

So are these irreconcilable differences, or do we give it one last post-Brexit, post-Trump shot at marriage counselling? Perhaps a greater understanding on both sides of the "threat stimuli" – left-wingers acknowledging existential dangers, however amplified, and that truly pluralist societies cannot simply be willed into existence; right-wingers recognising that their anxieties may be cognitive bias – could provide some let up.