In 2000, Michael Hardt, an associate professor of literature at Duke University, and Antonio Negri, a legendary figure on the Italian left, published a volume bearing the grand, stark title Empire. Even before it was listed in the Harvard University Press catalog, the appearance of the book was keenly anticipated among antiglobalization activists. Rumor had it that Empire would provide a definitive analysis of the new world order. It would be the theoretical bridge between postmodernist academics and a mass movement that was making it ever harder for international financial institutions to meet in peace. You can’t buy word of mouth like that. It did not hurt that Mr. Negri had spent much of the previous two decades in exile, convicted of having fomented civil disorder during the 1970s as the main theorist and éminence grise of a revolutionary group. (In 1997, he returned from France to serve out a prison sentence that he completed last year.) This is known as having street cred.

When Empire finally appeared, it was hailed as the Next Big Thing, by both scholars and the occasional intellectual fashion reporter for a major metropolitan daily. Empire eventually sold more than 40,000 copies. Few who purchased it ever reached a definite opinion about, say, the relationship between the World Trade Organization and the role of the philosopher Duns Scotus in subverting medieval ontology. Even so, Empire made its way into coffeehouses, and onto coffee tables ; and now there is a sequel, Multitude : War and Democracy in the Age of Empire (Penguin Press), prominently displayed at a bookstore near you, sometimes oddly situated alongside books by talk-show hosts or volumes of advice on managing your portfolio.

« Empire was really written for a university audience, » says Mr. Hardt, « for graduate students, more or less. » With Multitude, « we tried to write differently, for a much broader audience, while also doing a balancing act to make it interesting to scholars. »

Fredric Jameson, a prominent professor of comparative literature at Duke University, called Empire « the first great new theoretical synthesis of the new millennium » - a proclamation with much weight in the humanities. The reception that work received in the antiglobalization movement means that Multitude is getting some critical attention outside academe. Writing in The New York Times Book Review, Francis Fukuyama, a professor of international political economy at the Johns Hopkins University, complained that Multitude « lurches from analyses of intellectual property rules for genetically engineered animals to discourses on Dostoyevsky and the myth of the golem, » and that Mr. Hardt and Mr. Negri « take leave of reality » when discussing global politics.

That difference in judgment has nothing to do with any change in the thinking of Mr. Hardt and Mr. Negri between Empire and Multitude. While the new book is more accessible, it offers substantially the same theory as Empire. Where Mr. Jameson is the author of an influential Marxist analysis of postmodernism as « the cultural logic of late capitalism, » Mr. Fukuyama will always be remembered for having hailed the triumph of the United States in the cold war as « the end of history. » No surprise, then, that they should come to different estimates of the same theory. But another factor may also be in play. There is a certain urgency to Multitude, as the subtitle’s reference to war and democracy may suggest. After all, it was drafted between the September 11, 2001, attacks and the beginning of the invasion and occupation of Iraq.

No Justice, No Peace

Between September 11, 2001, and early 2003 the antiglobalization movement did not exactly die, though the crowds did thin. Politicians and pundits with no interest in the concept of a postmodern empire began talking about imperialism of the old-fashioned sort. And not always to denounce it. Perhaps (one current of thought went) the United States could export liberal democracy, or at least wipe out any terrorist threat to it. Glancing at their coffee tables, people wondered if perhaps Mr. Hardt and Mr. Negri had been on to something.

The prospect of a global Pax Americana might sound either utopian or nightmarish, depending on one’s politics. In any case, it bears no resemblance to the vision of Mr. Hardt and Mr. Negri. The world order they envision is far too complex for a single country to dominate it. The emergence of Empire, as they write in Multitude, involves a « state of war » that is « both global in scale and long lasting, with no end in sight ... strangling all social life and posing its own political order. »

Nor is that order compatible with democracy. Freedom is part of the collateral damage of Empire, « buried beneath the weapons and security regimes of our constant state of conflict. » Yet democracy does remain on the agenda. Forces emerging within (and against) the system of Empire will create a now-unimaginable form of global democracy. The hero of this revolutionary struggle is something Mr. Hardt and Mr. Negri call « the multitude. »

If their term sounds a little bit like « the proletariat » - well, that is not entirely accidental. During the 1960s and ’70s, Mr. Negri, then a professor of political science at the University of Padua, in Italy, published some of the densest works of Marxist theory every committed to paper. His followers in the revolutionary organization Workers Autonomy translated Mr. Negri’s work on « the social factory » (the idea that all sectors of life had become extensions of capitalist production) into frequent clashes with factory owners, politicians, and the police.

But the concept of the multitude actually comes from Mr. Negri’s later work on the philosopher Baruch Spinoza. As a graduate student in comparative literature at the University of Washington, Mr. Hardt published a translation of Mr. Negri’s book The Savage Anomaly : The Power of Spinoza’s Metaphysics and Politics (University of Minnesota Press, 1991).

The Dutch thinker’s pantheism and advocacy of constitutional democracy were extremely radical positions within 17th- century European philosophy. As Mr. Hardt and Mr. Negri reconfigure Spinoza’s work for the 21st century, his concept of multitudio sounds rather like identity politics. It includes « different cultures, races, ethnicities, genders, and sexual orientations ; different forms of labor ; different ways of living ; different views of the world ; and different desires. » The multitude, write Mr. Hardt and Mr. Negri, « can never be reduced to a unity or a single identity. »

The multitude can defeat Empire’s authoritarian « biopower, » write Mr. Hardt and Mr. Negri, through the decentralized « swarm intelligence » of continuing « network struggles. » (Perhaps the most appealing thing about Hardt-Negrian theory, at least for its enthusiasts, is its rather cyberpunkish political vocabulary.)

Makes Its Own Syllabus !

In an e-mail message, Mr. Negri writes, in Italian, that he is « clearly surprised by the success of Empire and Multitude » but considers it « important merely as a means of enlarging the discussion around the struggle. » While his work with Mr. Hardt is certainly being read by activists in the antiglobalization and antiwar movements, it has also found a ready audience in academe.

Harry Cleaver, an associate professor of economics at the University of Texas at Austin, was one of the first scholars in the United States to write about Mr. Negri’s work. He calls the collaboration with Mr. Hardt « an attempt to get out of the little back room of lefty circles, and reach a lot of other people, including postmodernists. » Empire has turned up on reading lists in a variety of disciplines in the humanities and social sciences. « It’s also being read in business schools, » says Mr. Cleaver, perhaps on the principle that business people should have some sense of a left-wing analysis.

If so, future M.B.A.’s ought to know that a considerable body of scholarship has been devoted to examining what some radical academics see as the hopelessly abstract character of Hardt-Negrian theory. Why develop a stratospheric theory of Empire, the critics complain, instead of analyzing the specific policies of, say, transnational corporations - or the American government ?

The abstractness is both a strength of the Empire theory and a source of frustration, says Charlie Bertsch, an assistant professor of English at the University of Arizona and a founding editor of the cultural-studies journal Bad Subjects. He admires the willingness of Mr. Hardt and Mr. Negri « to think big when most leftists seem to be thinking small. » And the concept of multitude, he says, « invites in readers who would be turned off by reference to ’the people’ or ’the masses.’ » The authors « offer a warm and fuzzy welcome to almost anyone, aside from those on the far right, who is willing to resist ’Empire’ as they define it. »

But Mr. Bertsch also says he sometimes « has a hard time getting traction in either Empire or Multitude, » because the authors « rarely get close enough to their topic to see its finer details. »

Mr. Cleaver, the economist, acknowledges that « a lack of concreteness » in the books « can leave readers skeptical. But there’s a lot more empirical background to the theories than is known to people reading them here. » During the 1980s and ’90s, he says, Mr. Negri and his colleagues in Europe published a large body of research on topics in economics, particularly concerning labor and immigration, in the French journal Future anterieur. « It was replaced recently by another journal called Multitudes, » he says. « Very little of the work in those journals has been translated into English. »

Even so, Mr. Hardt and Mr. Negri supply plenty of occasions to head to the library. Empire and Multitude generate their own rather demanding reading lists. In addition to Spinoza and Marx, they draw on ancient and modern political philosophers. Their footnotes reference scholarship on international economics and the history of the labor movement, in at least four languages. And some aspects of their work allude to another, even stranger, collaborative project : A Thousand Plateaus, the sui generis work of cultural theory by two French thinkers, Gilles Deleuze, a philosopher, and Félix Guattari, a radical « anti-psychiatrist. »

Endless Struggle

The product is a theory that sometimes resembles overstuffed luggage. What it does not resemble is the picture of the world familiar from dozens of other accounts of globalization.

As the boilerplate version has it, the contemporary economy and culture of the world are the culmination of the centuries-long spread of capitalism, and of its most-favored political environment, liberal democracy. That process can generate resistance from older cultural traditions. (It can even revitalize them, as in Islamic fundamentalism.) But the familiar story has it that globalization is an irresistible force, revealing the strength and dynamism of a market economy.

Not so, according to the Empire concept of Mr. Hardt and Mr. Negri. They, too, see the world becoming fully integrated into a purely capitalist order (a process Mr. Negri calls « real subsumption »). But that makes the entire planet into a giant factory, rather than a market. And ever more of the functioning of the global factory involves what Mr. Hardt and Mr. Negri call « immaterial labor. »

That term covers more than just the service sector or the information economy. A constant expenditure of creativity is required to keep the system running - through technological innovations, for example. The mass media « assemble » symbolic products, as if on an assembly line. And what sociologists have termed « emotional labor » is necessary to keep restitching the social fabric of capitalist life. As Mr. Hardt and Mr. Negri understand things, conflicts over intellectual property, cultural identity, and the availability of social services are struggles over the control of immaterial labor.

By e-mail, Mr. Negri says that « the combined efforts of my companions and me, some 30 years ago, to understand the transformation of current capitalism ... permitted us to engage in a definition of the new world order. » A share of the academic literature devoted to Empire has traced its themes back to the « workerist » and « autonomist » currents that emerged in Italian radicalism during the 1960s and 1970s. But as Mr. Hardt points out, their collaboration involves more than recycling old ideas.

They have sometimes spoken of « a force, almost an instinct of humanity, that rebels against authority, against oppression. » He calls that force « the ’always already’ multitude. » But their recent work, especially the latest book, stresses what Mr. Hardt calls « the ’not yet’ multitude - the possibility, today, of creating a political project based on the cooperation of fundamentally different groups and interests that remain different and independent, but nevertheless cooperate and act together. »

What Is to Be Done ?

But how does the teeming multitude « cooperate and act together » ? And why ? James Heartfield, who directs the University of Delaware’s program in London, is skeptical. In his book The ’Death of the Subject’ Explained (Sheffield Hallam University Press, 2002), Mr. Heartfield presents a rather old-fashioned Marxist critique of some of the poststructuralist theories that have shaped Empire and Multitude. In conversation, he describes Hardt-Negrian radicalism as an evasion of politics altogether.

« Whenever you galvanize a movement and band together to put forward demands, » he says, « you exclude others. This idea of ’multitude’ displaces the problem. At one point, Negri writes, ’Down with unity.’ Like a lot of people, he dreads that moment of mediation between mass democracy and representative democracy. But you can’t just get rid of the problem by defining it away. »

Asked about this criticism, Mr. Hardt responds, « We’re certainly not in the business of writing manifestoes, or What Is to Be Done ? » He does indicate, however, that his work with Mr. Negri has now reached the stage where they need to « think global democracy today » - that is, develop some notion of what would replace Empire.

« People spend a lot of time criticizing contemporary global institutions, and the insufficiency of national institutions as well, » he says. « The obvious thing, of course, is to ask : What would an alternative look like, and where would it come from ? » Some of those questions begin to emerge in the final pages of Multitude, but not the answers.

« Toni’s talking about volume three, » says Mr. Hardt. They are at the early stage of what sounds like a well-established routine. « We exchange letters about criticisms of the last book. We give each other reading lists. » (Eventually, someone’s academic career will be made from analyzing the documents of how an American professor and an Italian revolutionary collaborated on their books.)

After Empire and Multitude, Mr. Hardt says, « We need a little rest. » But it is clear that Mr. Negri is ready to push on to the next phase - defining a new vision of some still newer world order. The multitude waits, patiently or otherwise.