A couple of years ago, I had lunch with Peter von Hohenberg, grandson of the Archduke Franz Ferdinand, on a Danube river steamer, and naturally I asked him during our conversation what he thought might have happened had his grandfather not been assassinated in 1914. He thought that the Habsburg monarchy would not have fallen, since the Archduke was strongly in favour of reforms that would have defused the national issue. The First World War would not have happened because the Archduke was firmly opposed to the war party in Vienna, led by chief of staff Conrad von Hötzendorf (whose step-granddaughter, also at the lunch party, did not dispute this assessment). Peter did not say how history might have changed in the longer term, but it was clear that he thought we would all be living in a better world.

In his new book, Richard Ned Lebow does indeed make this leap of the imagination several times over. Claiming that he wants to restore a sense of chance and contingency to history and banish notions of inevitability, he canvasses a wide range of possible futures after the failure of world war to break out in 1914. In the absence of defeat in the war, Germany might have evolved into a constitutional monarchy or a peaceful democracy (no Hitler, no Holocaust); the Bolshevik revolution might have been avoided; the Armenians would not have suffered a genocide; and so on.

All this, and much more, could have followed on from a single chance event – the survival of the Archduke in 1914. But in fact, his assassination was not wholly a chance event and nor was the fact that it triggered world war. It was driven by Balkan nationalism, which in the First Balkan War, during the winter of 1912-13, had already brought Austria and Russia to the very brink of armed conflict. The Archduke’s assassination was part of a larger, longer-term conflict between Austria and Serbia, backed respectively by Germany and by Russia and France, that would have continued and quite possibly deepened even had the Archduke survived.

Historians spin out counterfactual scenarios such as this on the assumption that history is governed by chance, but once they have invoked a chance occurrence (or its absence, as in the case of the assassination of Franz Ferdinand), they become rigidly determinist. To assume that one antecedent would ineluctably have led straight on to a whole series of consequents is to invoke historical inevitability with a vengeance. Most counterfactual history is wishful thinking, and there is plenty of it here; the negative alternative scenarios presented by Lebow pale in comparison, but at least they are canvassed. Yet the fact that he spins so many contradictory counterfactuals out of a single event points to the essential arbitrariness of the procedure he employs.

There are many reasons why counterfactual history has become fashionable since the mid-1990s: postmodern playfulness and subjectivity; uncertainty about the status of knowledge in an era when digital manipulation can alter it at the touch of a button; the death of the grand narrative; and the disappearance of notions of linear progress in time and their replacement by a feeling of uncertainty about the future.

The reason why Lebow has championed counterfactuals is more personal, however. As a baby in 1942, he was handed to a French policeman by his mother as she was pushed on to a freight car destined for Auschwitz, and he owed his survival to a whole series of further chances that he recounts movingly in the opening chapter of this book. For him, perhaps, devising counterfactuals is a way of coming to terms with this experience by asserting his mastery over the seemingly unalterable facts of the past, amending them at will.

But while individual fates such as that of Lebow or, for that matter, the Archduke, are always subject to chance, the wider contexts in which they occur, whether it is the Nazi extermination of Europe’s Jews in 1941-44 or the headlong rush of Europe into war in 1913-14, are far less so. Thus, what historians can learn from counterfactual scenarios is in the end not very useful in trying to understand what actually did happen.