Reactions to news of the death, at the age of 100, of Henry Kissinger were predictably sharply polarised. It is difficult to think of any other Western politician in living memory who was as despised as he was fêted. It says much about both Kissinger and his detractors – and perhaps the effects of time passing and the maturation of political judgments – that many of his fiercest former critics were only too glad to be seen at one of his centenary parties earlier this year and were then among the first to lament the passing of a great statesman.

To those who reviled him he was a cynical, manipulative, ruthless, unprincipled and, in his own imagination, ‘born-again’ Metternich, transplanted into the heart of America’s East Coast establishment. In September 1973 Newsweek produced a mock-up of Thomas Laurence’s portrait of Metternich with Kissinger’s bespectacled and owlish head superimposed on the prince’s frockcoated torso.

To his admirers, fewer in number certainly, he was a superstar, a virtuoso of diplomacy who brought a much-needed dose of hardnosed realism to US foreign policy at a crucial moment in international superpower relations. Kissinger appeared on the cover of the same magazine in the following year as ‘Super K’, a cartoon hero.

To suggest that historical figures can be both amoral and significant political leaders would be banal. They clearly can be, but Kissinger deserves no banalities. There was little that was banal about his life or his legacy. They reflect the many vicissitudes, but also the many achievements and the essential brittleness of the ‘short 20th century’ (Kissinger’s lifespan, of course, was anything but short).

Kissinger was perhaps the most improbable of America’s chief diplomats until then, the first foreign-born and also non-Christian. Born into a Jewish family in Fürth, Bavaria, the heartland of the nascent Nazi movement, the 15-year-old left for America, via London, a few months before Kristallnacht. He spoke virtually no English and, until the end, retained a thick, gravelly Franconian accent.

Night school and shifts in a shaving-brush factory were followed by active service as an infantryman in 1944/5, and then as an army intelligence officer in charge of local administration in his now occupied native country.

After Harvard there followed spells as an academic historian, a think-tanker and eventually, for eight years, as National Security Adviser and then Secretary of State, during which time he collected – somewhat controversially – the Nobel Peace Prize. Kissinger left active politics in 1977 at the age of 54, and spent the next 46 years being Dr Kissinger, managing his highly lucrative brand as a global guru. During those eight years in office Kissinger shaped the course of world affairs more than many other political leaders of that period. Few have left such a lasting legacy, both intellectual and practical, as he did, based, in his case, on realpolitik, the view that foreign policy decisions had to be based on broader calculations of national interests, national security and the international balance of power rather than abstract ideals of democracy, human rights and liberty, at least outwardly the traditional points of reference for US foreign policy.

Kissinger was remarkably free from humanitarian cant, but to see him as an amoral and power-driven cynic would be simplistic. True, his view of international politics was bleak. From his studies of the history of great power relations he had imbibed something of the unforgiving nature of politics, where mistakes can be fatal, literally so. Therein lies the key to understanding Kissinger’s overriding concern with maintaining a stable global order and, in more recent years, with engendering a sense of a new but viable international order. In his Harvard viva voce Kissinger is reported to have quoted Goethe’s observation that order was preferable to justice. An apocryphal story, perhaps, but enlightening nonetheless. For this was not about abstract ideals but about limits and constraints. The exercise of power implies an obligation to accept the limits of self-restraint. And, to Kissinger, overreach, universal interference, was as dangerous as ‘under-reach’, isolationism.

Order did not mean standstill and merely managing the status quo. History, as Kissinger once suggested, ‘is the foe of permanence’. It might have been written with his own career in mind. He had the intuitive grasp of the circumstances under which he had to operate to see that détente with the Soviet Union was possible and that, given the deepening Sino-Soviet split, an opening to China could be brokered. He negotiated an end to the Vietnam War which had eluded previous administrations. Kissinger’s indefatigability gave rise to the concept of ‘shuttle diplomacy’, by which he brought Egypt to the point of signing an historic peace treaty with Israel and helped to coax Cairo from its long-standing alliance with the Soviets, thereby incidentally also marginalising their role in the Middle East.

At a time when the world has to deal with the realisation that pogroms are not merely matters of historical examination and when genocidal anti-Jewish hatred has crept into polite society, it is also worth noting that, almost surreptitiously, Kissinger opened the door for – admittedly only non-Israeli – Jews to work in places such as Saudi Arabia. Until the 1973 Yom Kippur War, most Western foreign services complied with Saudi requests not to deploy Jewish officials in that country. In 1974, the Saudis could scarcely reject the US Secretary of State. As Kissinger recounts in his memoirs, King Faisal, who loathed Jews and was in the habit of presenting visiting dignitaries with copies of the Protocols of the Elders of Zion – a notorious antisemitic forgery, alas, still widely in circulation as an ‘authentic’ document – received him with all the pomp due such an important ally.

No doubt Kissinger was vain, though his vanity was leavened by a healthy dose of self-deprecating wit. No doubt, also, he was thin-skinned, devious and manipulative, a perfect match for Richard Nixon. And yet that talent for deception and manipulation, both of negotiations and the cumbersome US foreign policy apparatus, helped to make international politics more stable and safer, and that for several decades.

His achievements have been denounced by many in the West, in this country most prominently first by William Shawcross and later, more egregiously, by Christopher Hitchens for using a sustained bombing campaign of neutral Cambodia while simultaneously negotiating an end to the war with the North Vietnamese. He has been accused of either deliberately or tacitly abandoning Bangladesh (then East Pakistan) to the tender mercies of Pakistan’s military dictator, and of condoning or encouraging, if not indeed orchestrating, brutal repression in Chile, East Timor and the Shah’s Iran.

The charge sheet compiled by Kissinger’s detractors on the neo-conservative right is of a different kind, but no less weighty. If the critics on the progressive left are the more vociferous and today the more prominent of the anti-Kissinger voices, it is important to remember that the first critics were ideological conservatives who considered East-West détente unduly lenient. Even today some, such as George F. Will, a prominent old-fashioned US conservative, suggest that Kissinger, a weary pessimist, overestimated Soviet power and was thus too ready to manage the Cold War when he should have concentrated on winning it.

It was the ascendancy of such hardline conservatives in the Republican party from the late 1970s onwards that ensured Kissinger’s exile from active politics after 1977. Whether out of genuine conviction or out of deference to powerful forces in the party, Ronald Reagan kept him at a distance; Kissinger was the kind of Republican – he was originally a Democrat and only later aligned with Nelson D. Rockefeller’s type of socially liberal but fiscally conservative Republicanism – that the now dominant neoconservatives thought lacked vigour and zeal in dealing with the Soviets.

Not all these criticisms are of equal merit. Most of them have one thing in common, however: they are strangely ahistorical. They lack a sense of context, and some also lack any, let alone deeper, insight into the nature of decision-making. Politics denies absolute certainty, and the statesman has ‘to peer into darkness’, as Kissinger argued; that is with imperfect knowledge of all the facts while manoeuvring in ‘a margin between necessity and accident’.

In other words, the act of decision is, in essence, a moral act: ‘an estimate which depend[s] for its validity on a conception of goals as much as an understanding of the available material’. More often than not, Kissinger stressed, foreign policy meant choosing between lesser and greater evils. To criticise any decision-maker for the consequences of their decisions, or that they came at a cost, rather misses the point. What critics ought to show is the range of alternative options that existed at the point of decision-making.

To do Kissinger justice – and admittedly not everyone will wish to do so – means to appreciate the context of the times and to grasp that there was throughout a hierarchy of strategic priorities. To demand an end to the Vietnam War, for instance, was one thing; to end it, as Nixon and Kissinger were committed to do, without endangering the superpower status of the United States and the cohesion of America’s alliance networks, involved identifying linkages to other issues to which Moscow attached greater importance than to humiliating its adversary in Southeast Asia. It also meant squeezing the Kremlin by exploiting the mounting tensions between the Soviets and Mao’s China. And it meant ratcheting up military pressure on the North Vietnamese, without which a diplomatic breakthrough would probably have proved elusive. Opening communications with the People’s Republic through Pakistani backchannels came at a price. It meant accepting the violent suppression of Bangladeshi opposition to Pakistani rule. It was an evil, but a lesser one than not forcing the Soviets to compromise by opening US policy to China. The attempt to stop Salvador Allende from becoming president of Chile in 1970 was a failure – the earlier failures to stop Castro in 1961 should have served as a warning – but the putsch that overthrew Allende three years later was more the result of internal forces than of interference by US intelligence.

Kissinger’s critics on the anti-communist right, meanwhile, need to ask themselves whether their own ultra-hawkish policy of a Second Cold War, with the aim of accelerating the collapse of communism, was at all feasible in the late 1960s and early 1970s. If anything, it might be argued that détente, the work of the West Europeans, especially the West German chancellor Willy Brandt, as much as of Nixon and Kissinger, not only gave the Soviets a stake in the international order. It also bought Western powers stability and the time needed for the Soviet system to embroil itself in its own contradictions. Attempts to upend the superpower system in the 1970s might well have encouraged the Soviet leadership, unencumbered then by economic malaise and not yet plagued by Afghan, Polish and other ulcers, to respond in kind.

It is not without irony that for someone who promoted his own views so assiduously, Kissinger was remarkably misunderstood. Wilfulness on the part of his detractors may be partly to blame, but the object of their wrath has to shoulder some of that blame, too. His writings are frequently opaque, suggestive of gloomy Teutonic metaphysics and advanced in a sub-Spenglerian sotto voce. Professional historians often looked askance at Kissinger’s works. His Diplomacy, the great Ernest May wrote in a New York Times Book Review, ‘is a book of maxims disguised as a history of statecraft’. ‘So what?’, one might be tempted to ask. Not many historians have maxims to offer that are worth contemplating.

At any rate, Kissinger’s statecraft still bears examination. Its starting point is candid analysis. During the last two decades of his life, he was often accused of being ‘soft’ on China, perhaps in order to protect his own business interests. Whatever the nature or extent of those concerns, Kissinger’s principal aim was to refute the rather facile arguments about rising and stagnating powers as destined to fight that draw on – historically not very accurate – parallels with the pre-1914 Anglo-German antagonism. In his analysis the Chinese leadership saw the existing global order as, in essence, America’s order, and wished to adjust, but not overturn, that system.

Objective examination of the prevailing forces is the first step in formulating policy but, when framing that policy, Kissinger’s other injunction needs to be borne in mind: the need for relative tolerance. His study of 19th-century great power diplomacy led him to the conclusion that the need for stability required states to learn to accept and live with each other’s differences. This, by the way, set Kissinger apart from Metternich (he thought Bismarck the more creative statesman). In his analysis, the main threat to peace always came from ideological zealots and assorted other proselytisers, who were ready to sacrifice stability in pursuit of their ideals. Hence his insistence that Beijing and Washington talk to build trust, identifying areas of common interest and avoiding matters where core differences are irreconcilable but might be cloaked in ‘constructive ambiguity’, such as trade or Taiwan.

Diplomacy can achieve only so much; and diplomatic success is ephemeral at best. The nature of Chinese policy might change; the attempt to forge a basis for co-existence might fail. Military deterrence, the implicit but credible threat of war, therefore, remains indispensable as the ultimate guarantor of peace, and it has to underpin all diplomatic strategy.

Diplomacy in the 21st century is good deal more challenging than when Kissinger was cultivating back-channels with Beijing or shuttling between Middle Eastern capitals. Secrets tend not to remain secrets for long in an age when every foreign minister feels the need for a social-media profile. The Cold War world of the East-West confrontation was more structured and more easily controlled, perhaps, than our multipolar present, in which often starkly competing versions of order compete with each other. All of this makes the need for stability and an order in which many can have a stake all the more pressing. And for that some Kissingerian sense of the delicate interaction between interests, different conceptions of order and the use of force is needed.

This is a tall order. Perhaps, no-one can live up to rise to the challenge. If they do, they will have to transcend the pieties of our age. One of Kissinger’s favourite quotes was reputedly Pope Urban VII’s comment on Cardinal Richelieu’s death: ‘If there is a God, the Cardinal de Richelieu will have much to answer for. If not… , well, he had a successful life.’ No wonder Kissinger liked it. Those who understand the vital necessity of stability should learn to like it, too.