Who belongs, and who decides? Demography as a problem for political philosophy
Falling fertility and ageing in rich societies, and migration across every border, force an old question back open: who makes up a political community, and who gets to decide? A reading through Arendt, Carens, Walzer, Miller, Pogge and Parfit.
Demography looks like the most settled of the sciences: births, deaths, the age pyramid, a curve projected out to 2100, a matter of arithmetic best left to statisticians. Yet behind the tables sits one of the oldest questions in political philosophy, and it is not a technical one. Aristotle, setting out the right size of the polis in the Politics, and Plato, fixing his ideal city at 5,040 households in the Laws, were doing demography. They were also asking who the citizens were, and how many of them there ought to be. The question has not aged. Who makes up a political community? Who counts, and after how long, as one of its members? And — a harder matter the ancients could pose but not resolve — how many people ought there to be at all?
None of this is abstract. Migration decides elections across much of Europe; border policy is a running source of constitutional conflict in the United States; in East Asia, populations ageing and shrinking faster than any in recorded peacetime are forcing governments to rethink assumptions a century old. Political philosophy spent much of the twentieth century reasoning about justice inside a closed society with a settled membership. John Rawls built A Theory of Justice (1971) on precisely that premise: a society one enters only by birth and leaves only by death. Demography is the fact that breaks the premise, and breaks it in more than one direction.
There is the question of who may cross a border and on what terms — the ethics of immigration proper. There is the prior question of who is entitled to decide, a puzzle democracies cannot settle from inside their own rules. And there is a third, which the Oxford philosopher Derek Parfit made genuinely difficult: when a policy shapes not only how people live but which people come to exist, and how many, what is being weighed? Take them in turn.
Start with who decides, because it comes before the others and is the least discussed. A democracy is government by the people — but which people? Majority rule tells you how a bounded group should reach decisions; it says nothing about how the boundary is drawn in the first place. You cannot put the question of membership to a democratic vote without first knowing who is entitled to vote in it, which is the very thing in dispute.
Robert Dahl noticed the gap in the 1970s, remarking that the problem of who legitimately makes up 'the people' had been "almost totally neglected by all the great political philosophers who write about democracy". Frederick Whelan gave it a name in a 1983 essay, 'Democratic Theory and the Boundary Problem', and argued that it generates a regress with no democratic exit: any rule for fixing the electorate must itself be authorised by some prior body whose composition was never democratically fixed. Robert Goodin has pressed the opposite horn — an 'all-affected-interests' principle, on which anyone whose life a decision touches should have a say — but that threatens to dissolve the nation into the planet, since a British budget or an American tariff reaches people in Lagos and Dhaka who hold no vote in London or Washington.
The German Society for Philosophy has launched a working group on philosophy and National Socialism, conceding that the subject has no settled place in research or teaching. In Beijing, sixty scholars debated how to build a 'Chinese autonomous philosophical knowledge system', a phrase that belongs to Xi Jinping. And a sociologist's book on reproduction in Palestine/Israel reaches a philosophy audience.
The boundary problem is not a curiosity. Every act of inclusion and exclusion a state performs — every naturalisation rule, every deportation, every grant or refusal of a passport — rests on an authority that democratic theory cannot itself supply. The decision is made; it is simply not made democratically, because it cannot be. Much of the heat in argument about migration is the heat of this unacknowledged gap.
Hannah Arendt saw the sharpest edge of the problem from the inside. In the ninth chapter of The Origins of Totalitarianism (1951), 'The Decline of the Nation-State and the End of the Rights of Man', she studied the stateless of interwar Europe — people stripped of nationality who found that the 'rights of man', supposedly owed to human beings as such, protected them not at all once no state would claim them. Her conclusion has not lost its force: the first right, the one that makes the others operative, is what she called "the right to have rights" — the right to belong to some political community at all. Lose that, and you do not fall back on a floor of universal human dignity; you fall through it.
This is why, for Arendt, the figure of the refugee exposes something the language of humanitarian aid conceals. A person who crosses a border fleeing persecution has lost not merely a home but a standing — the membership that turns an abstract bearer of rights into someone whose rights a particular authority is bound to honour. Seyla Benhabib, who received the Karl Jaspers Prize this year, has spent two decades reworking the paradox into a theory of migration, pairing it with Kant's thin 'right of hospitality' to argue that democracies owe outsiders at least a hearing even when they owe them no admission. The paradox remains unresolved, which is the point: a right that depends on membership cannot be guaranteed by appeal to a humanity standing outside all membership.
The strongest argument that borders should be far more open belongs to Joseph Carens, who made it first in a 1987 essay, 'Aliens and Citizens: The Case for Open Borders', and at book length in The Ethics of Immigration (2013). Carens takes the egalitarian commitments liberal democracies already profess and turns them outward. His memorable line is that "citizenship in Western liberal democracies is the modern equivalent of feudal privilege — an inherited status that greatly enhances one's life chances". We abolished the hereditary estates of the old regime because we judged it unjust that prospects should be fixed by the accident of one's birth. Yet the place one happens to be born remains the single largest determinant of a life's chances, and we defend it with fences.
Carens runs the argument through Rawls's own machinery. Behind a veil of ignorance, not knowing whether you would be born a citizen of a wealthy state or a labourer outside its gates, you would — he contends — adopt "the perspective of the alien who wants to immigrate" and count freedom of movement among the basic liberties. From that premise he concludes that "borders should generally be open and that people should normally be free to leave their country of origin and settle in another", subject only to the limits that already bind citizens.
Thomas Pogge sharpens the intuition into a charge. In World Poverty and Human Rights (2002) he argues that the affluent world is not merely failing to help the global poor but is actively implicated in their condition, through a shared institutional order it designs and from which it benefits. The duty at stake is then negative, a duty not to harm, which is harder to shrug off than any duty of charity. If the distribution of citizenships is one of the arrangements through which advantage is hoarded, an immigration regime is not a neutral act of self-protection but part of the machinery that produces the inequality. One need not accept the whole indictment to feel its pressure.
Against this stands an equally serious tradition, which has to be stated at full strength. Michael Walzer set the terms in Spheres of Justice (1983). "The primary good that we distribute to one another," he wrote, "is membership in some human community" — before any distribution of wealth or office, a community decides who shares in the distributing. From this he drew a conclusion liberal cosmopolitans find hard to swallow: "Admission and exclusion are at the core of communal independence. They suggest the deepest meaning of self-determination." A community unable to shape who joins it cannot, on this view, remain the community it is.
David Miller has given the position its most careful recent defence, in Strangers in Our Midst (2016). Miller is no nationalist of the blood-and-soil kind; he begins from a 'weak cosmopolitanism' on which all human beings merit equal consideration. He argues, nonetheless, that a people's right to control its borders follows from its right to self-determination: immigration alters the composition of the very body whose decisions are supposed to bind it, and, more contentiously, the social trust on which welfare states depend can be eroded by rapid change in the population. This does not licence closed doors. States have a duty to admit refugees, he holds, "as long as doing so does not carry a disproportionate cost for them"; it is economic migration that remains largely at a community's discretion. And once people are admitted they are owed full and equal membership, which is why he treats integration requirements and tests of civic knowledge as fair conditions rather than insults.
Will Kymlicka complicates the choice between these camps. In Multicultural Citizenship (1995) he argued that individual freedom is exercised against the background of a "societal culture" — a shared language and institutions that give a person's options meaning — so that justice can require protecting such cultures rather than dissolving them. He distinguished the claims of national minorities, which may warrant self-government, from those of immigrant groups, whose fair terms he saw as 'polyethnic' rights of accommodation within a society they have chosen to join, not a right to reconstitute it — granting the communitarians their point about cultural membership while denying that it must be ethnically closed. Philippe Van Parijs extends the thought to language: in Linguistic Justice for Europe and the World (2011) he defends a 'linguistic territoriality principle', the right of a community to protect its public language within its own territory, even while arguing for English as a global lingua franca and for redistribution across borders. Belonging, on both accounts, comes in a thin civic form and a thicker cultural one, and much of the quarrel over migration is a quarrel over which of them a state may insist on.
Here the philosophy meets a fact neither camp can wish away. The United Nations' World Population Prospects 2024 puts the global fertility rate at 2.3 live births per woman, down from 3.3 in 1990 and closing on the replacement level of 2.1; more than half the world's countries and areas are already below it. World population, around 8.2 billion in 2024, is now projected to peak at roughly 10.3 billion in the mid-2080s and then decline — the UN assigns an 80 per cent probability to a peak within this century. In 63 countries and areas, home to more than a quarter of humanity, the peak is already past.
The leading edge is in East Asia. South Korea's fertility rate fell to 0.721 in 2023, the lowest ever recorded for a sizeable nation, before edging up to 0.748 in 2024 — barely a third of replacement. Japan recorded 686,061 births in 2024, below 700,000 for the first time and a ninth consecutive record low, with a fertility rate of 1.15. A society reproducing at those rates faces a shrinking workforce supporting a growing body of the old, and the obvious arithmetical remedy is immigration — the very thing Japan and South Korea, among the world's most reluctant recipients of migrants, have been least willing to accept even as their numbers fall. Germany has tried the opposite, easing skilled migration and citizenship rules in the name of demographic necessity; its recent elections show how fragile the licence for that bargain can be.
A striking feature of the debate is how little of humanity actually migrates. On UN figures there were about 304 million international migrants in 2024, close to double the 154 million of 1990 — yet still only 3.7 per cent of the world's people, the great majority of whom live and die in their country of birth. Migration is, for most of the planet, a contested idea rather than a lived experience, and an unequal one: the freedom to move expands for citizens of rich states and contracts for the poor, so that mobility is itself a form of the inequality Carens and Pogge describe. The politics runs hot out of all proportion to the numbers, one reason the subject keeps testing the limits of democratic norms.
The last question is the strangest, and demography poses it most directly. Fertility, climate and pension policy all turn on judgements about future people, who have a peculiar standing: their identities, and whether they exist at all, depend on the very choices we are trying to assess. Parfit made the difficulty precise in Reasons and Persons (Clarendon Press, 1984). His 'non-identity problem' observes that a policy which seems to harm 'future generations' often brings into being the particular individuals who live under it; those people cannot complain of having been made worse off, since the alternative was not a better life for them but no life at all. Ordinary moral reasoning, built around identifiable people helped or harmed, loses its grip.
Worse follows when we ask whether a larger population or a smaller one is better. If what matters is the total quantity of good lives, Parfit showed, we are driven towards what he christened the Repugnant Conclusion: that "for any possible population of at least ten billion people, all with a very high quality of life, there must be some much larger imaginable population whose existence, if other things are equal, would be better, even though its members have lives that are barely worth living". Almost no one accepts this, and four decades of effort have failed to produce a population ethics that avoids it without some equally unwelcome result. When a government frets about a 'birth dearth' and sets out to raise fertility, or an environmentalist argues for fewer people, each is making a claim about how many lives there ought to be — a claim the best work on the subject suggests we do not know how to ground.
This is where the three threads draw together. The boundary problem asked who is entitled to decide the membership of a political community; Arendt showed what befalls those left outside every such community; Parfit's puzzles extend the question across time, to the unborn, who cannot be consulted and whose existence is itself the stake. A state setting immigration quotas, a couple deciding whether to have a child, a parliament designing a pension system for 2080 are all answering the question the Politics and the Laws first raised: who shall there be, how many, and on whose authority.
No camp holds all the cards. The cosmopolitans are right that the birthright lottery is hard to justify to anyone who takes equality seriously; the communitarians are right that self-government without any control over membership is a hollow thing, and that a politics which refuses to speak to the human attachment to place and people tends to hand that language to its ugliest claimants — a point Michael Sandel has pressed against his own liberal tradition. What demography has done is remove the comfort of treating these as questions for another time. The numbers are in, the populations are already turning, and the oldest question in political philosophy is being answered every day — by border guards and registrars rather than philosophers, and mostly without anyone noticing it was a question at all.
Dundee has suspended its single honours philosophy degree and approved a philosophy-and-AI programme instead; Hertfordshire has stopped recruiting; Kingston's research centre has left the university altogether. Meanwhile the labs hire, Floridi speaks of a 'haemorrhage' and the Fed's table is quoted as vindication. An audit of what the year has actually established.
This afternoon in New York, under the French presidency, the Security Council holds its first meeting devoted to the possibility that frontier AI systems slip out of human control. The briefers are Yoshua Bengio and the chief executives of OpenAI, Anthropic and Hugging Face. Whether the Council is the right room is itself in dispute.
.jpg?width=500 "Kant")
Comments
0Loading comments…