The distinction between 'refugees', 'asylum-seekers' and 'economic migrants' is becoming harder to sustain. All are seeking shelter against violence, whether political or economic. The woman who dies in childbirth for want of basic medical care, a child who perishes from avoidable sickness, are no less dead than someone persecuted for belonging to a minority ethnic group or for holding the wrong political opinions.

The tragic cargo of 58 dead Chinese migrants which reached Dover in Britain last June is emblematic of the unfreedom of the free-market ideology which is supposed to govern our lives. The British Government and press were swift to condemn the trade in human misery, but showed little inclination to do anything about the production of human misery. Who can believe that a global system which claims to benefit humanity can grant greater freedoms to goods and money than to flesh and blood?

We are all, and always have been, economic migrants - a status intensified since the beginnings of industrial society. Survivors of the Irish famine who found their way into Liverpool cellars before the long journey to America; the violent abduction of slaves; the shipping of pauper apprentices from the workhouses of southern England to the mills of Yorkshire: the story of economic migrants is our story in the North also. And not only in the past. Even in our time we have been evicted from familiar patterns of livelihood, scattered from the old industries and sent to make our accommodation with the nebulous but compelling necessities of the 'new economy', with its novel mutations of servitude - even when this means abandoning all that we have loved in exchange for places where we remain perpetual strangers. Sometimes, it seems, all humanity has been set in motion, a restless one-way journey away from rootedness, identity, self-reliance.

Migrants are conspicuous in almost every country in the world with their archaic country manners and their peasant responses not yet adapted to the altered rhythms of industrial society. From ruined forests and bleak monocultural plantations they have come to live in subterranean rooms that never see sunlight - in the slums of São Paulo and Nova Iguaçu, in basements that fill with stagnant green water in the rains. Faces from the High Andes stare impassively above sandwich boards like playing cards, advertising the services of pawnbrokers and moneylenders on the streets of Lima and Rio de Janeiro. They arrive at bus stations after 36 hours in a battered bus, and there they recognize with gratitude the faces of compatriots who promise them lodging and a job and then disappear with their money or belongings. A couple sits on an abandoned sofa in the centre of Manila, the man in baseball cap and trousers tied with string, the woman in a grubby, pink, quilted dressing gown; on their faces the mental confusion of the uprooted. They remind us of the upheavals of the early industrial period. In England and Wales in 1780 there were 40 lunatic asylums; by the 1840s there were 400.

They shelter in boxes under the cement motorways of American cities. They stand on the railway termini of Europe beside a cardboard case or tin trunk, hugging shabby coats against an unfamiliar climate, a precious slip of paper in their hand with a scribbled contact in the poorer parts of Vienna or Frankfurt, where trams rattle past tenements that serve as punitive barracks for transients. They lodge near the station in Rome, six beds in a single room, the feral smell of lone men on lumpy mattresses, unshaven chins, badly nourished by makeshift meals and the thin consolation of porn magazines and remittances home to Tirana, Karachi or Colombo. The International Monetary Fund (IMF) may recognize the $65 billion they send in remittances, but it cannot count the cost of severed relationships, the absence of fathers, the spaces where loved flesh and blood should be. They stand in exile, in canvas shoes and creased plastic, on the edge of a world to which they will never belong - although one day, they hope, their children may call this harsh landscape home.

They can be glimpsed in the fortresses of Jeddah and Doha; Filipino, Vietnamese, Nepali faces, a smudge behind the security grilles of Knightsbridge and the Parc Monceau. Sometimes captive, they sleep with mice and cockroaches in the warmth of restaurant kitchens. They share sub-lets in public housing, four bunk-beds on a carpetless floor. They rattle their pails and mops in the wintry Northern dawn, cleaning expanses of ceramic floor, marble and glass, dusting the leafs of giant indoor plants that grew wild at home. They must put away their certificates and degrees and forget what they know. Their wallets hold letters falling apart at the folds from having been read and re-read, the photographs of children they would no longer recognize.

In the wake of the Totenschiffs (Ships of Death) drifting around the world with their cargoes of perishable humanity, it has recently become thinkable to discuss renewed immigration into Europe. The words 'labour shortage', 'skills deficit', 'bottlenecks' have been heard for the first time in a generation. It is also suggested that we need 'new blood' to help look after an ageing population.

The idea is, in part, a recognition of the impossibility of insulating national entities against the consequences of globalization. Such 'economic migrants', however, are not the unskilled, the uprooted, those displaced from subsistence farms, the development refugees and the slum-dwellers denied a livelihood in the carceral suburbs of Africa and Asia. Europe is not going to open its doors to them. At least, not officially.

Those required are the labour élite of the Third World, educated at great expense by their governments, the computer programmers, the doctors and nurses, the engineers and social workers - precisely those most desperately needed by their own or other poor countries in the world.

But there is another story which may not be publicly told. Waves of economic migrants have always been necessary to 'dampen inflationary pressures' - a tendency which the US is more prepared to recognize than Europe. The six-million-or-so illegal immigrants in the US, many working at levels of bare survival, serve to lower wages and check inflation. Their illegal status is redeemed by economic legitimacy - an equation as yet apparently too advanced for a Europe preoccupied with racisms old and new.

So the official ideology remains. Money and goods - and some vital personnel - are unstoppable in the perpetuum mobile of globalization. But poor people must stay at home. Only the cream of the skilled may be filtered through to sustain the growing wealth of Europe. Those who manage to evade the restrictions to cross closed frontiers - in leaky boats that do not sink off Brindisi or Bari, in suffocating container trucks via Hungary and Romania, stowed away in ships, aircraft or trains - may be absorbed into an industrial anonymity which will permit them to do their bit for inflationary pressures here. We may be sure that only the most determined will actually evade the obstacles. In other words, the prohibition on economic migrants is actually a form of triage which will ensure a passage only to the most resourceful. In this stringent test the unfortunate 58 Chinese in Dover were clearly not the fittest.

This is why the hysteria engendered by the discovery of the new slave trade is hypocrisy. The humanitarian genuflexion to the fate of a cargo of dead - and therefore unproductive - human labour is quite absent when people perish of want, poverty and malnutrition in their own country, even though the institutions of enforcement are the manipulators of their destiny also.

And this illuminates the relationship between what is called the 'developing world' and the West. If globalization has set the peoples of the world in movement, it is because their economies are being compelled into the pattern familiar to us. Only theirs is a caricature of the freedoms we had at our disposal. Their people do not have the great empty spaces, evacuated by centuries of genocide, racism and land-grabbing. They have nowhere to send their surplus populations. They are implementing imperial economic policies without the economic hinterland to support them. They have seen the dispossession of self-reliance, the ruin of subsistence, the export-driven necessity of offering the labour of their peoples at the cheapest rate that survival allows - and sometimes even cheaper.

Here is the epic contradiction in the barriers to movements of humanity. The necessities of globalization did not begin with them, but they bear its consequences. To preserve the people of privilege from the suffering of those whose ruined lives have made such a significant contribution to their well-being: this is the function of 'economic migrants' whose mobility must be disallowed but whose passage through the closed frontiers of the lands of plenty is essential for the control of wage-inflation and the perpetuation of economic success.

Migrants, sometimes traumatized and disoriented, driven to despair and crying their rage on windy street-corners, the preachers of apocalypse outside the Underground stations, the mangled casualties of unchosen mobility, hardened, embittered by abuse and humiliation - we should recognize ourselves in them because they reflect our own often thwarted search for an elusive peace in a violent and unstable system. They embody the migrations forced upon us over the generations. Just as we imagine we have found a moment of calm and prosperity, when we can breathe freely and bring up a new generation, everything is swept away and we are moved on. Our own journeyings are also away from security, self-reliance, belonging.

We should pay more attention to the fate of migrants, for they are our own past made flesh-and-blood. They are, after all, not bogus asylum-seekers or illegal immigrants, but victims of bogus market forces and coercive ideologies of absent global freedoms.