State: “independent political communities each of which possesses a government and asserts sovereignty in relation to a particular portion of the earth’s surface and a particular segment of the human population, what may be called internal sovereignty, which means supremacy over all other authorities within that territory and population. On the other hand, they assert what may be called external sovereignty, by which is meant not supremacy but independence of outside authorities.”

Here are a few of the notes struck by our authors:

The return of Asia to the world stage will define the era.
The chasm between the United States and China could widen as their differing interests become more pronounced.
Emerging powers, even democratic ones, will have separate agendas, making international integration more difficult.
Cooperative approaches to an array of global issues, such as climate change, will be difficult to accomplish.
Nonstate actors, ranging from unofficial governing entities to terrorist organizations, will grow, particularly in weak states.
The United States' influence, diminished by the rise of other states and nonstate actors, will be fatally undercut if the country does not curb its unsustainable reliance on debt.
Avoiding famine will depend on a vast expansion of Africa's lagging agricultural productivity.
The resurgence of all the major religions will be marked by post-Western versions of Christianity and a return of religious practice to secular Europe.
Half the world will experience "fertility implosions," thus leading to shortages of working-age populations, with only sub-Saharan Africa producing a surplus of working-age men.
The technology revolution, epitomized by the Internet, will empower both people yearning for democracy and repressive tyrants.
The United States will remain the primary source of clean-energy innovation.
Those states that best educate their citizens will win the economic competition.

the changing balance of power among states and peoples, the urgency of planetary issues

The global religious landscape in the coming years will be affected by the massive shift in population growth from the developed countries of the North -- predominantly in western Europe and the former Soviet republics -- to the developing countries of the so-called global South. The North accounted for 32 percent of the world's population in 1900, 25 percent in 1970, and about 18 percent in 2000. By 2050, it will likely account for just 10 percent. Religion has emerged as a driving factor in this redistribution. Religiosity is now one of the most accurate indicators of fertility, far more telling than denominational or ethnic identity, since religious people tend to have more children than their secular counterparts.

Religion is on the rise around the world. If the United States fails to confront the implications of this growth properly the potential for religiously motivated violence across the globe may increase dramatically over the next century.

After decades of following Deng Xiaoping's dictum "Hide brightness, cherish obscurity," China's leaders have realized that maintaining economic growth and political stability on the home front will come not from keeping their heads low but rather from actively managing events outside China's borders. As a result, Beijing has launched a "go out" strategy designed to remake global norms and institutions. China is transforming the world as it transforms itself. Never mind notions of a responsible stakeholder; China has become a revolutionary power.

China's leaders have spent most of the country's recent history proclaiming a lack of interest in shaping global affairs. Their rhetoric has been distinctly supportive of the status quo: China helping the world by helping itself; China's peaceful rise; and China's win-win policy are but a few examples. Beijing has been a reluctant host for the six-party talks on North Korea, it has tried to avoid negotiations over Iran's potential as a nuclear power, and it has generally not concerned itself with others' military and political conflicts. China's impact on the rest of the world has, in many respects, been unintentional -- the result of revolutions within the country. As the Chinese people have changed how they live and how they manage their economy, they have had a profound impact on the rest of the world. China's position as the world's largest contributor to global climate change is not by design; it is the result of extraordinary economic growth and 1.3 billion people relying on fossil fuels for their energy needs.

Yet all this is about to change. China's leaders once tried to insulate themselves from greater engagement with the outside world; they now realize that fulfilling their domestic needs demands a more activist global strategy. Rhetorically promoting a "peaceful international environment" in which to grow their economy while free-riding on the tough diplomatic work of others is no longer enough. Ensuring their supply lines for natural resources requires not only a well-organized trade and development agenda but also an expansive military strategy. The Chinese no longer want to be passive recipients of information from the outside world; they want to shape that information for consumption at home and abroad. And as their economic might expands, they want not only to assume a greater stake in international organizations but also to remake the rules of the game.

Today, more than 50 percent of the world's population has access to some combination of cell phones (five billion users) and the Internet (two billion). These people communicate within and across borders, forming virtual communities that empower citizens at the expense of governments. New intermediaries make it possible to develop and distribute content across old boundaries, lowering barriers to entry. Whereas the traditional press is called the fourth estate, this space might be called the "interconnected estate" -- a place where any person with access to the Internet, regardless of living standard or nationality, is given a voice and the power to effect change.

For the world's most powerful states, the rise of the interconnected estate will create new opportunities for growth and development, as well as huge challenges to established ways of governing. Connection technologies will carve out spaces for democracy as well as autocracy and empower individuals for both good and ill. States will vie to control the impact of technologies on their political and economic power.

the rise of state capitalism

Bremmer has best identified this new twist to the story of globalization in his book The End of the Free Market. The title is a misnomer. The book is really about the rise of state capitalism, also the subject of a recent essay by him in this magazine. Whereas 20 years ago, the list of the largest companies in the world was dominated by private firms, it is now dominated by state-owned entities, many from emerging markets. China's state-owned companies now not only utterly dominate its economy -- of the country's top 100 companies, 99 are state controlled -- but also increasingly play a large role on the global landscape. They play by different rules and have different goals than do private corporations from the West.

Reminders of the limits of theory ring true to practical people. But if causes and effects are hopelessly random, then there is no hope for informed policy. Terminal uncertainty, however, is not an option for statesmen. They cannot just take shots in the dark, so they cannot do without some assumptions about how the world works. This is why practical people are slaves of defunct economists or contemporary political theorists. Policymakers need intellectual anchors if they are to make informed decisions that are any more likely to move the world in the right direction than the wrong one.

This is a reminder that simple visions, however powerful, do not hold up as reliable predictors of particular developments. Visions are vital for clarifying thinking about the forces that drive international relations, the main directions to expect events to take, and one's basic faith in matters of politics, but they cannot account for many specifics in the actual complexity of political life. The biggest ideas may also yield the least accurate estimates. The psychologist Philip Tetlock, in Expert Political Judgment, compiled detailed scorecards for the predictions of political experts and found that ones known for overarching grand theories ("hedgehogs," in Isaiah Berlin's classification) did worse on average than those with more complicated and contingent analyses ("foxes") -- and that the forecasting records of any sorts of experts turn out to be very weak. Readers looking for an excuse to ignore dire predictions might also take comfort from evidence that forecasting is altogether hopeless. Nassim Nicholas Taleb, the author of The Black Swan, argues that most world-changing developments turn out to be predicted by no one, the result of highly improbable events outside analysts' equations. The overwhelming randomness of what causes things in economic and political life is inescapable, Taleb argues; big ideas are only big illusions.

Right now, with dollar interest rates low and the currency more or less steady, this fiscal slide is more a matter of conversation than concern. But this calm will not last. As the world's biggest borrower and the issuer of the world's reserve currency, the United States will not be allowed to spend ten years leveraging itself to these unprecedented levels. If U.S. leaders do not act to curb this debt addiction, then the global capital markets will do so for them, forcing a sharp and punitive adjustment in fiscal policy.

The result will be an age of American austerity. No category of federal spending will be spared, including entitlements and defense. Taxes on individuals and businesses will be raised. Economic growth, both in the United States and around the world, will suffer. There will be profound consequences, not just for Americans' standard of living but also for U.S. foreign policy and the coming era of international relations.

THE ROAD TO RUIN

It was only relatively recently that the United States became so indebted. Just 12 years ago, its national debt (defined as federal debt held by the public) was in line with the long-term historical average, around 35 percent of GDP. The U.S. government's budget was in surplus, meaning that the total amount of debt was shrinking. Federal Reserve officials even publicly discussed the possibility that all of the debt might be paid off.

The U.S. government is incurring debt at a historically unprecedented and ultimately unsustainable rate. The Congressional Budget Office projects that within ten years, federal debt could reach 90 percent of GDP, and even this estimate is probably too optimistic given the low rates of economic growth that the United States is experiencing and likely to see for years to come. The latest International Monetary Fund (IMF) staff paper comes closer to the mark by projecting that federal debt could equal total GDP as soon as 2015. These levels approximate the relative indebtedness of Greece and Italy today. Leaving aside the period during and immediately after World War II, the United States has not been so indebted since recordkeeping began, in 1792.

The twenty-first century began with a very unequal distribution of power resources. With five percent of the world's population, the United States accounted for about a quarter of the world's economic output, was responsible for nearly half of global military expenditures, and had the most extensive cultural and educational soft-power resources. All this is still true, but the future of U.S. power is hotly debated. Many observers have interpreted the 2008 global financial crisis as the beginning of American decline. The National Intelligence Council, for example, has projected that in 2025, "the U.S. will remain the preeminent power, but that American dominance will be much diminished."

Power is the ability to attain the outcomes one wants, and the resources that produce it vary in different contexts. Spain in the sixteenth century took advantage of its control of colonies and gold bullion, the Netherlands in the seventeenth century profited from trade and finance, France in the eighteenth century benefited from its large population and armies, and the United Kingdom in the nineteenth century derived power from its primacy in the Industrial Revolution and its navy. This century is marked by a burgeoning revolution in information technology and globalization, and to understand this revolution, certain pitfalls need to be avoided.

Mearsheimer's vision is especially telling because it is an extreme version of realism that does not see any benign actors in the system and assumes that all great powers seek hegemony: "There are no status quo powers . . . save for the occasional hegemon that wants to maintain its dominating position."

Mearsheimer, however, is an unregenerate realist, and he threw cold water on the Cold War victory. Bucking the tide of optimism, he argued that international life would continue to be the brutal competition for power it had always been. He characterized the competition as tragic because countries end in conflict not out of malevolence but despite their desire for peace. In the absence of a world government to enforce rights, they find it impossible to trust one another, and simply striving for security drives them to seek control of their environment and thus dominance. If peace is to last, it will have to be fashioned from a stable balance of power, not the spread of nice ideas. In short, there is nothing really new about the new world.

Fukuyama de-emphasized mainstream liberalism's focus on materialism and justice by stressing "the struggle for recognition," the spiritual quest for human dignity and equality (or sometimes for superiority), as a crucial ingredient in the transformation.

In times of change, people wonder more consciously about how the world works. The hiatus between the Cold War and 9/11 was such a time; conventional wisdom begged to be reinvented. Nearly a century of titanic struggle over which ideology would be the model for organizing societies around the globe -- fascism, communism, or Western liberal democracy -- had left only the last one standing. After a worldwide contest of superpowers, the only conflicts left were local, numerous but minor. What would the driving forces of world politics be after the twentieth century, the century of total war?

Among the theorists who jumped into the market for models of the future, three stood out: Francis Fukuyama, Samuel Huntington, and John Mearsheimer. Each made a splash with a controversial article, then refined the argument in a book -- Fukuyama in The End of History and the Last Man, Huntington in The Clash of Civilizations and the Remaking of World Order, and Mearsheimer in The Tragedy of Great Power Politics. Each presented a bold and sweeping vision that struck a chord with certain readers, and each was dismissed by others whose beliefs were offended or who jumped to conclusions about what they thought the arguments implied. (Reactions were extreme because most debate swirled around the bare-bones arguments in the initial articles rather than the full, refined versions in the later books. This essay aims to give the full versions of all three arguments their due.)

Policymakers in Beijing, looking to strengthen China’s economy, are no longer satisfied with the country’s position as the world’s manufacturer. Their solution is to break China’s dependence on foreign technology, moving from a model of “made in China” to one of “innovated in China.”

The Chinese phrase for indigenous innovation, zizhu chuangxin, was introduced in a 2006 state-issued report, “Guidelines on National Medium- and Long-Term Program for Science and Technology Development.”