The history of humanity is a history of conflict. For all of recorded history, tribe has fought tribe, kingdom has fought kingdom, empire has fought empire.
Perhaps the greatest continuity of history is the desire of humans to harm other humans, differentiated by skin colour, beliefs, or language. Right across the world, people have sought to identify themselves with a group they were born into, and accepted unflinchingly the idea that the group perceived as different is by extension an enemy. Thus Spaniard fought Inca, Japanese fought Korean, Catholic fought Protestant. Rather than seek to understand and coexist with the other, these groups sought to attack difference.
The ideas underpinning the demonization of difference, that great precondition of genocide and conflict, have names. Racism. Tribalism. Ethno-nationalism. For the groups established by these ideologies to be meaningful, they must exclude people. They exclude not on the basis of a chosen characteristic, but an unchosen one.
In humanity's apparent need to self-identify, positive characteristics are acquired by 'us'. By extension, 'they' acquire negative characteristics, reaffirming our own identity. The colonist, therefore, became intelligent, paternal and civilised whilst the colonised became stupid, childlike and savage.
From the demonization of difference, it is a small step to genocide and war. It becomes easy to blame ones problems on a group of people who are excluded from the public arena, and are therefore denied a right of reply. To seek to harm that group is only to step from thought to action.
Because the demonized characteristics are imagined and not real, education is the antidote. By exposing the fundamental humanity underlying difference, prejudice and the problems it causes can be attacked at their root.
Our personalities and values may be wildly different, says the nationalist, but we are fundamentally similar as we are both British, so that difference may be tolerated. Within the national or tribal community, difference is not a threat because the perceived similarity is greater. All it takes is to show that the scope of similarity is global and not national to break down the arbitrary unity of the tribe or the nation, which in reality is the greatest source of disunity known to mankind.
Yet we have the chance to change this. We have been presented with the hammers to demolish the Berlin walls of nationhood, tribe and race. Mass media, Facebook, BBC World News - these products of globalisation are making difference more accessible. They are the tools of a global education.
When famine strikes Ethiopia, I know about it. When a tsunami devastates the Bangladeshi coast, I see the effects on my TV screen. When a Korean invents a popular dance, people in Cuba may watch and emulate it. And the result, for many, is empathy. For the first time in human history, all wealthy governments have foreign aid budgets. Aid spending is miniscule compared to the capacity of rich to help poor, but rich countries feel obliged to give nonetheless. Many choose to donate to help people whom they will never actually meet. An insufficient but increasing number are concerned about the consequences of genocides for people thousands of miles away.
As a human race, we may take two paths. The first is to embrace the seedlings of a common human conscience. To take this path is to scrap national education systems, and instead teach our children the history of the world's people. It is to campaign for foreign languages to be taught in schools. It is to stand against racism and embrace diversity. This path rejects the artificial barriers which divide us. This is the path to peace.
The other path is to withdraw from a world in which resources are increasingly scarce, to say 'I would rather eat cake than let the whole world eat bread'. It is to discriminate on the unchosen factor of location of birth, to say "why should my money be used to help Somalis eat when it could make 'my own people' rich? " It is to reproduce the zero-sum game of country v country, tribe v tribe, people v people.
Globalisation offers us the chance to embrace a universal human community. It entails a moral minimum of the most basic conditions of coexistence: that we care about one another's survival and seek solutions not through violence but through discussion at the table of brotherhood. Within that community, diversity can flourish. Which path is it to be: isolation and conflict, or engagement and peace? Only we can decide. But the conditions of our century - greater interconnectedness and a global public sphere - give us a historically unprecedented opportunity. I urge you to embrace it, so say yes to difference today and we can be united in that affirmation.