Tony Judt was often admired for his supposed English pragmatism and resistance to intellectual dogma. The historian became famous in the early 1990s with a scathing attack on the illusions that French thinkers long harboured about communism. In the eyes of his numerous critics, attacking the left just after the end of the cold war took little courage or originality.

Judt was to prove them wrong: during what in retrospect appears as a strange interregnum between the fall of the Berlin Wall and the reappearance of global geopolitical conflict, he often ventured to disturb what he called “the easy peace of received opinion”, influencing people but losing many friends in the process.

His broadsides against an age of “post-totalitarian” self-satisfaction were not those of a self-promoting provocateur, however. Their ammunition could be found in Judt’s enduring political passions: about the moral role of his adopted country – the United States – in global politics; the future of social democracy; and Israel, for whose army he had volunteered as a translator during the Six-Day War.

All of these passions are on display in When the Facts Change, but so is Judt's capacity for combining them with political realism and a sense of historical possibility.

Judt died of Lou Gehrig’s disease in 2010 at the age of 62. His widow, Jennifer Homans, has assembled a number of his essays from the mid-1990s on. Homans, herself a historian, has also written a beautiful and moving introduction that conveys something of how Judt’s forceful personality and his writing hung together.

Changes of mind

Precisely because he was so sure of his moral commitments, Judt could alter his stance on questions of the day rather abruptly – if he was presented with new empirical evidence. Hence the title, which cites a saying commonly attributed to John Maynard Keynes: “When the facts change, I change my mind. What do you do, sir?”

Judt cared little what others thought of him: the present volume contains a number of devastating attacks on major figures, such as Judt’s fellow historian Norman Davies. His most controversial essay appeared in 2003; in it, he called Israel an anachronism, which caused his detractors to cry anti-Semitism and “self-hating Jew”. Few engaged with his core argument that a state committed to being both Jewish and democratic might end up being neither, if it kept occupying territory and excluding large parts of its own (Arab) population. It was Judt the historian who claimed that the very idea of a “faith-driven ethno-state” constituted a throwback to 19th-century European ideologies of national purity.

Yet, as we learn from this posthumous volume, a binational polity for Jews and Arabs was not Judt’s last word. In a 2009 text, Judt reverted to a two-state solution, which, invoking Churchill, he termed the worst answer except for all the other ones. He conceded that his binational scheme would require trust – but if there were trust, then there would long have been a Palestinian state on the map already.

Judt pointed to Northern Ireland to suggest that in any successful peace process, the moderates get squeezed out and powerful brokers will push the extremists to strike a deal. First, Judt recalls, Bill Clinton had to stop Irish-Americans from supporting the IRA, then Clinton and Tony Blair talked with Ian Paisley and Gerry Adams. The implication for the Middle East is clear: sideline the Jewish-American community and start negotiating with Hamas.

US foreign policy

Positions like this did not make Judt many friends in the foreign policy establishment that dominated Washington in the George W Bush years. Neither did his relentless reminders that the US occupies a unique global role, not just because of military might, but also because many other states trust its good intentions – a reputation neoconservatives blithely risked during the Iraq War and after. And neither did his unashamed advocacy of what he simply referred to as “social democracy”.

For his detractors, there was an obvious contradiction here: had Judt’s own stance in the 1990s not contributed to discrediting leftist ideals? Such black-and-white thinking (was he for us or against us?) overlooks that, in Judt’s eyes, Marxism and the free-market triumphalism of the post-1989 period shared a crucial trait: they both worshipped economic necessity and told stories of inevitable progress.

The cheerleaders of capitalism were as deluded as 20th-century ideologues of the Left – and might yet get us into what Judt presciently called a form of “Chinese capitalism . . . Western style”, where markets are unfettered but citizens subject to surveillance and control of movement and opinion.

The alternative to such a dystopia remained, in Judt’s eyes, a reinvigorated social democracy. Social democracy, he argued, had long become the prose of European politics: all spoke it, but political poetry (and inspiration) had to be found elsewhere. He pointed out that the success of the postwar welfare state kept undermining its appeal: fewer and fewer remembered how economic disaster in the 1930s (especially for the middle class) had driven people to political extremes.

Judt warned of a “new age of insecurity”. If social democracy had any future at all, he said, it would have to be what he called a “social democracy of fear” – not a set of idealist promises, but a constant reminder of what had gone wrong during the 20th century.

Even for sympathetic readers, Judt’s judgment here seemed to become clouded by nostalgia: instead of facing up to the challenges of a new era, he appeared to fall back on a glorified image of the British welfare state (and the public railway system, to which two essays in this volume are devoted and on which he had planned to write a major book). The historian seemed to have forgotten the fact that women and minorities had not exactly been central to the mid-20th century social democratic vision (and that the pre-privatisation British Rail could be pretty awful, even if worse was to come).

Change policies

True, Judt did not shy away from the seemingly contradictory notion of a Left committed to conserving – its past achievements, that is. But he also knew that Humpty Dumpty could not be put together again. He called on social democrats to renew their moral appeal, their distinctive poetry, if you like – and to change policies, if necessary.

This book presents a remarkable record of an age that probably has just passed. (Many observers rightly suspect that 2014, with Putin’s annexation of Crimea, brought the post-cold war period to an end.) It also allows a more dispassionate assessment of a major public intellectual’s work as a whole. What Judt said about the French historian François Furet turned out to be true of himself: Furet was “incapable of remaining detached from contemporary politics” and “the unity of his oeuvre perhaps suffered accordingly”.

What Judt quoted from Furet’s writing on Alexis de Tocqueville also proved an accurate picture of himself: his “achievement . . . does not lie in any single doctrine but in the acute and sometimes ambivalent ways he confronted the questions of equality, democracy, and tyranny that arose in his time and that continue unresolved in our own”.

Jan-Werner Müller teaches politics at Princeton University