In their thoughtful responses to my essay, Nils Gilman, Michael Costigan and Ulrich Beck agree with me about the naïveté of "the new cosmopolitanism" that leads thinkers like George Monbiot and Daniele Archibugi to support a "world parliament." Instead, in different ways they make the argument that the nation-state is losing authority and capacity to non-national entities and forces. As distinct from the new cosmopolitanism, which calls for the nation-state to be weakened from above by new layers of supra-national political authority, this account of the erosion of the nation-state from below and beside might be described as "the new medievalism."

Gilman and Costigan point to "transnational criminal organizations" like drug smugglers and "transnational financiers." But neither drug smuggling nor international financial flows are evidence that the US and similar countries are losing their capacity to police their borders and their economies.

Drug use and drug smuggling on a large scale are tolerated in the US as a matter of informal policy, notwithstanding the letter of the law, because most Americans have judged that the cost of effective suppression would be too great. Since other countries effectively crack down on smugglers of similar drugs, the problem is with the culture and politics of Latin American states, not our policy. And if we were to legalize drugs, it should be because it's in our interest, not a foreign country's.

The global deregulation of finance and industrial outsourcing, far from being imposed on a weakening nation-state, have been enthusiastically promoted under Democratic and Republican administrations alike for decades. Critics of these policies may argue that they serve special interests that have captured the government, at the expense of the public interest. But there is no doubt that the US possesses the institutional capacity to encourage or compel the "insourcing" of manufacturing, as China does, or to adopt capital controls, of the kind that Brazil has recently used, if a domestic political consensus were to coalesce in support of those policies.

Like Gilman and Costigan, Beck agrees with me that political world federalism is naïve. He uses the term "cosmopolitanization" as a synonym for what is usually described as "globalization" -- that is, an alleged over-arching pattern of social transformation driven by increasing economic integration and immigration, among other trends.

In asserting the power of cosmopolitanization (or globalization), Beck relies on anecdotes rather than evidence and treats marginal phenomena as though they represented new norms. For example, he writes: "Long-distance love and global families are no longer marginal phenomena; they have long since taken up a position at the heart of the 'majority society.' The global other is in our midst and acquires here a literal, intimate, family connotation... The unity of language, passport, skin color and household that had seemingly prevailed as the national model of the family since the beginning of time is now breaking down."

Really? According to the United Nations, in 2010 only 10 percent of the world's population in developed countries was foreign-born. In the world as a whole, a mere 3.1 percent of the human race lived in countries other than those in which they were born. The overwhelming majority of people on earth will live, work, marry and die in the countries in which they are born, notwithstanding Beck's unrepresentative examples: "One's brother-in-law now has a wife from Thailand" and "A woman from Poland has been hired to look after grandpa."

As for what he calls "the unity of language, passport, skin color and household," in former white supremacist countries like the US, increasing interracial marriage actually strengthens the nation-state by creating a new, larger, inclusive national majority in place of the former exclusive white majority. The amalgamation of two or more ethnic groups into a single new ethnic group with a common, hybrid culture does not increase diversity, it reduces it. Immigration similarly reinforces existing nations, as long as immigrants assimilate after a generation or two to the majority culture, while contributing a bit of cuisine or a custom or two, as most immigrants do in the US, rather than permanently maintaining separate languages and cultures in ethnic enclaves.

If the nation-state system is not doomed by migrant flows, even less is it threatened by the practice of transnational organ transplants, which Beck uses as a symbol of a post-national world: "Muslim kidneys purify Christian blood. White racists breathe with the aid of one or more black lungs. The blonde manager gazes out at the world through the eye of an African street urchin." This is striking as poetry, but surely the number of individuals with organs from individuals of other nationalities is too insignificant to serve as a basis for a grand theory of transformation of the world order.

Beck's argument that we must shift from a nation-based society of "fate" to a global society based on "risk" because modern risks cannot be confined in space or time or insured against and have "incalculable" consequence is interesting. But it is undermined by his own list of examples: Fukushima, the euro crisis, global warming, and SARS. Notwithstanding some fallout in the region around Japan, the Fukushima accident was not only essentially a local Japanese problem but also one that has been successfully dealt with by the Japanese nation-state. International financial panics and pandemics have been around for ages; if the lethal post-World War I influenza epidemic and the Great Depression did not render the nation-state system obsolete, why should far less damaging disasters like the SARS epidemic and the Great Recession do so now?

The relative inaction of governments in response to climate change, I would argue, reflects not incapacity, but conscious decisions by governments either that particular measures like cap-and-trade would not be effective or that they would impose costs greater than their benefits. In the case of global warming, as in the cases of drug smuggling and financial flows, inaction reflects particular choices by governments, not incapacity on their part in a neo-medieval world of weak states and strong non-state actors.

Truly epochal transformations of global society are few and far between. The shift from an agrarian civilization organized on the basis of multi-ethnic monarchies and city-states to an industrial civilization with states based on popular sovereignty, in which the sovereign "peoples" are identified in practice with ethnocultural nations, has been occurring since the eighteenth century and is largely complete, although a few multinational states may yet break up along national lines. Nothing lasts forever, but nobody has yet provided any compelling reason to believe that we are living in the twilight of the nation-state era rather than in its dawn.

Michael Lind is policy director of the Economic Growth Program at the New America Foundation and author of the forthcoming Land of Promise: An Economic History of the United States.