Perhaps it is living half your life in Pakistan, for Pakistan is the land of the pure. Literally so: the land, stan, of the pure, pak. Perhaps that is why you have come to question the commonly held perception that purity is good and impurity is bad. For a tribe of humans newly arrived in a location never before inhabited by humans, such an outlook is perhaps sensible. Purity in a stream of water renders it fit to drink. Impurity in a piece of meat sickens those who eat it. Purity is hence to be valued and impurity to be avoided, resisted, expelled. And yet you believe the time has come to seek to reverse, at least partially, the emotional polarity of these two words, to extol impurity’s benefits and denounce purity’s harms.

The issue is, of course, personal. We are each of us composed of atoms, but equally we are composed by time. Since your time has been spent half inside Pakistan and half outside, and your outlook and attitudes shaped by this, you are in a sense half-Pakistani, which is to say, as Pakistan is the land of the pure, you are half-pure: an impossible state. You cannot exist as you are. Or rather, you must be impure. And if impurity is bad then you are bad. And to be bad is hazardous, in any society. So yes, the issue is personal, and pressing.

In the United States a politics of white purity is marching in white hoods and red baseball caps

But in Pakistan, the issue is political as well, for it affects everyone. Once purity becomes what determines the rights a human being is afforded, indeed whether they are entitled to live or not, then there is a ferocious contest to establish hierarchies of purity, and in that contest no one can win. No one can ever be sufficiently pure to be lastingly safe. In the land of the pure, no one is pure enough. No Muslim is Muslim enough. And so all are suspect. All are at risk. And many are killed by others who find their purity lacking, and many of their killers are in turn killed for the same reason. And on and on, in a chain reaction. The politics of purity is the politics of fission.

This should not be surprising. Pakistan was founded by fission, the splitting of British imperial India into two separate independent states, Muslim-majority Pakistan and Hindu-majority India. And Pakistan has experienced further fission, the splitting of its western and eastern wings into Pakistan and Bangladesh. In each case, a more complex entity was broken into what was believed would be two more internally harmonious ones. But a retreat from complexity is no guarantee of future harmony. Too often, it is accompanied by the rise of a fetish for purity, the desire to exterminate lingering traces of complexity within.

Pakistan is not unique. Rather, it is at the forefront of a global trend. All around the world, governments and would-be governments appear overwhelmed by complexity and are blindly unleashing the power of fission, championing quests for the pure. In India a politics of Hindu purity is wrenching open deep and bloody fissures in a diverse society. In Myanmar a politics of Buddhist purity is massacring and expelling the Rohingya. In the United States a politics of white purity is marching in white hoods and red baseball caps, demonising Muslims and Hispanic people, killing and brutalising black people, jeering at intellectuals, and spitting in the face of climate science.

Facebook Twitter Pinterest Neo Nazis, alt-right and white supremacists march in Charlottesville, Virginia, in August 2017. Photograph: Samuel Corum/Anadolu Agency/Getty Images

And what of Europe? Europe, too, is rekindling its love affair with purity, with signs of this deadly ardour everywhere, from the rise of the far right in Germany and Austria to the endless emergency in France to the ethno-national cracking of Ukraine and Spain.

And then there is Brexit, particularly saddening for you, since you are not just part-Pakistani, you are part-British (and part-European) as well. Brexit illustrates only too well the politics of fission and the unleashing of the forces of purity. First, or so it was said, the British took back control. But the Scottish and Northern Irish seemed not to want to take back control. So the English took back control from them. And also from Londoners, for London had long ceased to be properly English. And also from the young, addled in their thinking by the ever increasing numbers of the non-English in their midst. In some English newspapers today dissenters are called traitors. In England’s north-west frontier, which is to say Northern Ireland, a return to violence is feared. The ruling party is paralysed, riven by factionalism. No one is deemed pure enough, brazenly English enough, to govern. Judges, journalists, parliamentarians, citizens: everyone is suspect.

How Pakistani it all strikes you.

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In these pure times, you believe more impurity is desperately needed. Only impurity can save us now. But, fortunately, there are reasons for hope. Our species was built on impurity, and impurity will probably come to our rescue once again, if we let it.

Breakthroughs are likely to come from mongrelisation. From impurity. From people and ideas at risk of being suppressed

Biology is instructive here. The physical commingling of two human parents is required to produce a child. Every child is a combination of genetic material from two different sources. Every child is impure, a mix. There is a clear reason for this: it works better than the alternative. If we simply split in half to produce two humans from one, or detached a lump from our leg or from our buttock, which grew into an identical copy of us, we would all be the same. We would all be pure. But we would be much less capable of coping with the challenges of an environment that always has been, and always will be, in a state of change.

Over time, our inescapable, systemic, fundamentally human impurity gives us the capacity to do what has not been done before, to make creative leaps: in our biology, in the diseases we can resist and the foods we can digest. And in our thinking and culture and politics too. The coming together of people from different backgrounds, with different ideas, allows breakthroughs to occur. Constitutional democracy as currently practised around the world owes a great deal to America and Britain and France, but it also owes a great deal to the ancient Greeks, and to the Arabs who built on and transmitted Greek thought to a Europe where the ancient Greeks had been all but forgotten. The first aircraft was invented in America, but the physics and mathematics and engineering that made it possible came from Europe, from North Africa, from India, from China, from the collision and collection of knowledge by all of humanity.

Facebook Twitter Pinterest ‘The coming together of people from different backgrounds, with different ideas, allows breakthroughs to occur ... think of jazz.’ Photograph: Frank Driggs Collection/Getty Images

Think of jazz. Of Asia and Africa’s influence on European cuisine – and vice versa. Of the Moors on Don Quixote. Of the foreign-born on Silicon Valley. Of the green revolution. Of cutting-edge research in medicine. These are not victories of purity, designed by cutoff, like-minded people of similar appearance and narrowly shared ancestry. These are what can be achieved when humanity mixes.

Climate change. Mass migration. Rampant inequality. None of the most pressing and daunting problems today facing humanity have simple answers. As a species, we require creative new approaches, yet-to-be-imagined leaps forward. But while we might not yet know what the solutions to these challenges are, we should already suspect from where the breakthroughs are most likely to come. They are likely to come from mongrelisation. From profound impurity. From people and ideas at risk of being suppressed and marginalised in our purity-obsessed age.

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We are all impure. But because many of us deny our impurity, those who are most obviously impure among us require allies. And one of their most important allies is literature. Writing. Reading. When, sitting alone, we read a book, something profoundly strange occurs. We are by ourselves. We are only ourselves. And yet we contain within us the thoughts of another person, the writer. We become something bizarre. Something manifestly impure. A being with the thoughts of two beings inside it.

A reader, in the moment of reading, experiences a pooling of consciousness that blurs the painstakingly constructed boundaries of the unitary self. The very possibility of reading, the fact that it can occur, that a human being can experience this, the thoughts of another in the same physical place, that place so deep within, where the reader’s own thoughts reside – and furthermore that the reader is drawn to this experience, seeks for it, desires it – reminds us that the impure is fundamental to what we are, and calls out to us, powerfully, like the sea calls out to an organism that has evolved to live on the land, and yet recreates the sea inside itself, forms a watery womb, every time it conceives a child.

A reader experiences a pooling of consciousness that blurs the painstakingly constructed boundaries of the unitary self

Writing and reading are, as sex is, a commingling. Literature is the practice of the impure. Written words might articulate demands and justifications for purity, but the fact that such words are written and read means they are, by their very nature, impure – prudes perhaps, but inescapably engaged in an orgy. Writing cannot help but remind us of the power of impurity, even when some written words claim the opposite.

So yes, writing is among the most important allies of the impure, which is to say it is on the side of the mixing upon which our future ability to thrive as a species depends, and on the side of the mongrelisation that has produced each of us individuals; a mongrelisation that, if acknowledged, allows us to accept ourselves as the messy, fertile, multifaceted composites we actually are, rather than the frozen, sterile, monochromatic entities we are told to pretend to be.

(For you, of course, possibly more obviously a mongrel than many others, writing has become a way of life, the way of your life, because it was not clear to you that a life such as yours had a way without it.)

But writers are easily identified as agents of impurity. And so it does not surprise you, and should surprise none of us, that the forces of purity have identified writing and writers as in need of suppression.

These suppressions do not occur in a vacuum. For each, there is a context. Individual impurities are cited as harmful. As offensive to a set of beliefs, or to a desired cohesion, or to an economic future, or to the wellbeing of a younger generation. And then a mode of suppression is selected: a legal one, such as libel laws in Britain or lèse-majesté laws in Thailand or national security and official secrecy laws in America; or an extra-legal one, such as kidnapping by a drug cartel in Mexico, or a religious proclamation by a cleric in Pakistan, or the bullet fired by an assassin, anywhere, everywhere.

Facebook Twitter Pinterest Houses of Rohingyas burning in Myanmar, in September 2017. Photograph: NurPhoto/Getty Images

Such suppression almost never presents itself as an attempt to end free speech in general. Rather, it focuses on the specific. Not the herd, but the lamb. Not the school, but the sardine. On this one particular case of impurity, which has gone too far, and can now, should now, be picked off, swallowed up, in a mighty gulp, never to be heard from or seen again.

Because of this merciless specificity, a scattering occurs, even among those who seek to defend the impure who are writers. You have often observed this tendency. It manifests itself in a focus on the threats to those impurities that we like, to the forms of speech we ourselves tend to value. For many in Europe, for example, this is the threat of violent Muslims against speech perceived as anti-Islam. But while this threat is real and dangerous (albeit encountered much more by writers in Asia and Africa than in Europe), it is not the only threat. Indeed it is not the largest nor the most significant one, in terms of the numbers of writers it affects and the aggregate amount of harm that befalls them. Around the world the dangers writers face come from criminals, from the powerful in their societies, and from their own governments, far more often than from Muslim terrorists.

To focus only on one form of suppression, then, while ignoring the others, runs the risk of seeking to harness indignation as a weapon, rather than as a shield. Of failing to value the impurity of writing, and instead opening a new front in the battle of one purity against another.

When we celebrate writers for their bravery, it is also worth asking if there are writers whose bravery consists, in part, of standing up not to others but to us. Standing up not to the monsters without, about whom we speak so often, but to the monsters within, which we prefer not to notice. Writers who undermine our cherished nations, militaries, borders, races, clans, beliefs.

For there are many kinds of heroes, or rather many uses for them. There are those heroes who inspire. But there are heroes, too, who remind us of our own potential for villainy, impure mirrors who reflect back at us the false purities we hide. Such writers may go unsung, understandably. But when they go unprotected, we risk losing with them the possibility for the best within us, that redemptive impurity we shall badly need in the times to come.