A CASE can be made that realists are mostly right about the dynamics of world politics—but not necessarily about the major actors. What if the main actors in world politics are, and will continue to be, not many independent nation-states but a small number of more or less permanent hierarchical, multinational blocs, each led by one or more dominant nation-states?

The belief that the world in the industrial era is being organized into one or a few military-economic-political agglomerations goes back to the nineteenth century. The idea helped to inspire the late nineteenth-century competition among Western powers for overseas possessions. It was also the underlying cause of both world wars, which occurred when German and Japanese regimes sought to carve out and consolidate their own blocs or empires through regional conquest.

In The Managerial Revolution (1943), James Burnham, a former Trotskyist who became a founder of American Cold War conservatism, predicted that three major blocs would emerge after World War II, with the United States, Germany and Japan as nuclei. His work influenced the dystopian vision of George Orwell’s 1984, of perpetual low-level conflict among the imaginary superpower blocs of Oceania, Eurasia and Eastasia.

Burnham proved to be a poor prophet. World War II gave way to a bipolar world order, with the United States and Russia, now “superpowers,” as rival bloc hegemons, Japan a U.S. satellite, Germany divided between the blocs, and East Asia and other regions contested by the superpowers in proxy wars.

But Burnham, true to the Marxist tradition from which he had only recently emancipated himself, sought to integrate a theory of global economic and social change with his theory of geopolitics. This was, and remains, an advantage for something like Burnham’s approach against contemporary mainstream Western academic approaches to world order, which tend to isolate a single factor and try to build a theory on it.

IN INTERNATIONAL-RELATIONS theory, neorealism in its purest form isolates power, usually equated with military power. Some variants try to explain the foreign policies of particular states as reactions to conditions of polarity: bi-, multi-, uni- or a-. Meanwhile, in another department on the university campus, conventional neoclassical economics ignores both nation-states and blocs as economic actors in their own right and theorizes trade in terms of individuals and firms specializing in an idealized global market that does not exist. In yet another academic silo, housed elsewhere in the university, is found political theory, including theories of liberal democracy, which tend to pay little attention to real-world developments in national security or the economy.

Idealized models can be useful in some lines of scholarly endeavor. But they are not helpful in understanding world politics. In this case, the three isolated approaches of international-relations theory, academic economics and political philosophy can yield a hypothetical world in which each state, in theory, can join one set of security alliances for purposes of military protection, a different trade bloc for commercial purposes and a third set of international alliances, perhaps drawn together by political creed and social values.

In the real world, this kaleidoscopic complexity does not exist. There has always been significant alignment among nations in the military, economic and political realms, both during the Cold War and in the quarter century since its conclusion.

In Europe, there is a high, though imperfect, degree of overlap between membership in NATO and membership in the European Union. And there is strong pressure for members of both the EU and NATO to conform to a common liberal-democratic ideology. For example, Poland and Hungary today are condemned by other EU and NATO members as dangerously backsliding “illiberal democracies” for controversial policies involving public television (Poland) and the regulation of nonprofits and immigration (Hungary)—policies that, in comparison with those of autocratic China or Saudi Arabia, are hard to distinguish from those of their “liberal” European neighbors.

Elsewhere, there is significant overlap between military alliance membership and membership in trade blocs. The “megaregional” trade pacts promoted by the Bush and Obama administrations, the TTIP and TPP, were intended in part to bolster U.S.-led security alliances in Europe and East Asia. China’s proposed Regional Comprehensive Economic Partnership was equally geopolitical in its manifest intent, including many of the same Asian nations as the TPP but excluding the United States. And there is significant overlap in membership among the Shanghai Cooperation Organization, a military alliance headed by China that includes Russia, and new economic institutions promoted by China, including the BRICS’ New Development Bank and the Asian Infrastructure Investment Bank. Vladimir Putin’s Eurasian Economic Union is as much a geopolitical as a commercial project.

To treat security and trade policy as distinct realms, each with its own internal logic and unconnected to the other, can only make us as confused as the sages in the Indian fable about the blind men and the elephant who did not realize that what they felt—a snake-like trunk, a leaf-like ear, a tree-like leg—were in fact parts of the same beast. The beasts, in this instance, are blocs.

Taking blocs seriously means rejecting the idea of the national interest as a list of discrete priorities, in favor of recognizing that the national interests of both dominant and subordinate powers are often defined by leaders as the preservation or expansion of the bloc to which they belong.

For the hegemonic power that orchestrates a bloc, the bloc multiplies national military power and wealth by adding foreign populations and foreign resources to its own. Given low fertility rates and the difficulty of raising productivity levels by innovation, the quickest and most effective way to boost the overall GDP of a bloc is to add more countries to it.

A bloc can even augment the status of second-tier powers. For example, the population of the Eurasian Economic Union—which includes Russia, Belarus, Kazakhstan, Kyrgyzstan and Armenia—is 179 million, compared to only 143 million for Russia itself.

Needless to say, strength based on territorial expansion as well as internal growth was the strategy of past empires. In the modern era, based on the rules of national self-determination and popular sovereignty, incorporation of additional territories by conquest would be resisted as illegitimate. But blocs that are similar to informal empires can be built up by means of security alliances and trade deals, which may be hard to distinguish from de facto colonialism where one partner is a weak protectorate and the other a great or superpower.

AT THIS point, neoclassical economists and libertarians (two overlapping sects) may object that in a global free market the size of economic blocs would not matter. That is true but irrelevant; a borderless global market has never existed and, in the absence of a world government, never will exist. In a world economy divided among great-power blocs, industries with increasing returns to scale, like manufacturing, are likely to be most productive and dynamic in the blocs with the largest integrated markets—that is to say, the internal markets of populous nation-states and even more populous blocs. Technological and commercial efficiencies enabled by scale can, in turn, permit higher growth, higher per-capita income and the possibility of raising more taxes in absolute terms, even with lower rates of taxation—taxes to be spent on, among other things, the military. This is the successful strategy the larger and richer American bloc used to drive the smaller and poorer Soviet bloc into bankruptcy. In a zero-sum, mercantilist world of rival blocs, the bigger the bloc, the better.

For the leaders of relatively weak and small countries—that is, the majority of countries in the world—membership in a bloc can also bring benefits, even if power relations within the bloc are more hierarchical than egalitarian. The exporters and importers of small nations can be guaranteed access to bloc-wide markets and suppliers, and incorporated into bloc-wide supply chains. As de facto protectorates of the bloc’s dominant nations, weak countries can engage in “free riding” when it comes to defense, spending relatively little on the military.

In addition to being united by shared security and economic interests, blocs may be united by a sense of shared identity or values. The Communist regimes in the Warsaw Pact and the Soviet republics paid lip service to Marxist-Leninist ideology. Today, not only liberal democracy in the abstract but an ever more left-wing version of it—characterized by support for multiculturalism and mass immigration—is becoming something like the official ideology of the European Union. In Europe, many members of the social elite claim to consider themselves “Europeans” first and British, French, Spanish or Greek nationals second.

But modern blocs can exist without this third element of common identity and values, on the basis of shared military and economic policies alone. Saudi Arabia remains part of the U.S. bloc, although its values could hardly be more antithetical to America’s liberal and democratic creed. And the approach to international relations, including bloc building, of the Chinese and Russian governments has been described as “sovereigntism”—a high degree of respect for (or indifference to) the internal politics and social structure of allies and clients.