The Shield of Achilles: War, Peace and the Course of History, by Philip Bobbitt

Adam Roberts asks what will happen to states built for warfare in a businesslike new world

WH Auden's poem "The Shield of Achilles" was a depiction of the awfulness of 20th-century mass warfare, set against a more heroic, classical vision. The relationship between society and war may now be taking new turns. That is the starting point of this blockbuster on the history and future of the modern state. I opened it with dread, due mainly to an extreme suspicion of grand surveys propounding a theory to explain the past, present and future of international politics. Truth is more chaotic, more varied, and comes in smaller packages. However, after reading this extraordinary study my enduring suspicion is tempered by more than sneaking respect for the author and his achievement.

Philip Bobbitt, who holds a chair in constitutional law at Austin in his native Texas, has had a varied career. He has been a visiting fellow in Oxford and London; has held senior posts on national security in Washington, in both Democratic and Republican administrations; and has written books on subjects as varied as nuclear strategy, social choice and constitutional law. All this experience and range of interests come together in this book. "Only connect" could be its motto.

Bobbitt's main thesis is that the constitutional system of a state is inextricably entwined with its perception of war. This link between what he calls the "inner and outer faces" of the state has frequently been ignored, not least by academics. Bobbitt adds international law as another candidate for rescue from compartmentalisation. In his coverage of Germany and the US, he demonstrates convincingly that the nation-state is the product of the worlds of strategy and law: their common sources, collisions and interactions.

Joining with gusto in the historians' game of re-labelling wars, even world wars, Bobbitt sees epochal significance in the "Long War" that started in 1914 and ended in 1990. The two world wars plus the Cold War constitute a whole: a three-phase, three-way struggle to determine which version of the nation-state was to triumph: the ethnically based expansionism of Germany, the universalist state socialism of the Soviet Union, or the liberal democracy of the US and Britain. Ironically, the very triumph of the liberal version in 1990 coincides with the transmutation of the nation-state into something else, the "market-state".

Bobbitt is right to argue that, despite predictions of its imminent demise due to globalisation and other factors, the state is a remarkably resilient institution that is not about to disappear. Instead, it is doing what it always does: adapting to circumstances. In response to the revolutions in computation, communications and weapons of mass destruction that brought the Long War to an end, what seems to be replacing the nation-state is the market-state. This can assume many forms, but in essence the state is reduced to being a minimal provider or redistributor.

As for war, governments are floundering to produce convincing security policies for the post-1990 world. Bobbitt suspects that the nation-state's preparedness for war against other well-organised states has to yield to the requirements of a new world in which the most serious threats come from non-state bodies. He suggests (wrongly in my view) that it is because they are too "national" that states can't cope well with terrorism.

Despite, or because of, his familiarity with legal issues, Bobbitt is sceptical about international law. It has generally not lived up to expectations. Some attempts to advance the role of international law are nothing more than parochialism writ large: foisting the constitutional values of one state (usually the US) on a world inhabited by different, even antithetical, values and traditions. He argues that the concept of universal international law that animates the UN Charter is destructive of the society of states and their security. Yet he concedes that it is impossible to abandon a law-based approach to international relations, and resolutely rejects the reductionist fantasies of some so-called "realists".

Like all attempts at global generalisation, Bobbitt's work invites sceptical questioning. Does he exaggerate the universality of the "nation-state" model as the pre-eminent constitutional form of the 20th-century? Many states, including the UK and Switzerland, managed to stagger through the century with complex multi-national forms, and their own visions of how the world ought to be, that differed in key respects from Bobbitt's picture of the nation-state.

When he generalises about the new era of the market-state, he seems in fact to be thinking much more about the US than other states. His coverage of international bodies including the UN is disappointing, not because his criticisms are necessarily wrong, but because they lack specificity. His surprisingly extended coverage of the Yugoslav wars of the 1990s is too argumentative to fit within the essentially reflective work of this book.

Oddly, this encyclopaedic work neglects some European prophets of the effects of globalisation, including Karl Marx, whose Communist Manifesto envisaged the early disappearance of national differences, and Norman Angell, whose Great Illusion argued that war had become too costly to be waged by rational states. If they could have got it so wrong, how can one be confident that Bobbitt hasn't? Some writers whom he does mention are misunderstood. Hedley Bull's classic work, The Anarchical Society, is described as advancing a view of international relations as a Hobbesian state of nature. In fact Bull argued that there is an international society of sorts, and it does work after a fashion. That moderate view – distinct from the traditions of idealism and realism – may be a useful starting point in addressing the post-1990 world.

For all its sins of omission, commission and repetition, this is a remarkable book. If Bobbitt has the temerity to advance some intoxicating global generalisations, he also hands out plenty of hangover cures. He vigorously attacks the beliefs that our own times are unique or our culture universal. He accepts that the world may now be too complex for a single paradigm. He can be subtle and nuanced. If he exaggerates the uniqueness of our own post-Long War world, if he has written several passages best skipped, if he delves too much into the future, I still defy you to read this and claim your understanding has not been enriched.

Adam Roberts is professor of international relations at Oxford University