THE term ‘genocide’ conjures up attempts to kill an entire people: the German slaughter of the Jews and the near-extermination of the Native Americans. But the identity of the crime does not depend on its scale or success: genocide means “acts committed with intent to destroy, in whole or in part, a national, ethnic, racial or religious group”.

Though, in 1995, the women and children of Srebrenica were first removed from the killing grounds by Bosnian Serb troops, though the 8,000 men and boys they killed were a small proportion of the Bosnian Muslim population, it meets the definition.

So the trial of Ratko Mladic, the troops’ commander, which began last week, matters. Whatever one thinks of the even-handedness of international law, and though it remains true that men who commissioned or caused the killing of greater numbers of people (George Bush and Tony Blair, for instance) have not been brought to justice and are unlikely to be, every prosecution of this kind makes the world a better place.

So attempts to downplay or dismiss this crime matter too — especially when they emerge from the unlikely setting of the internationalist left. I’m using this column to pursue a battle which might be hopeless, and which many of you might regard as obscure. Perhaps I have become obsessed, but it seems to me to be necessary. Tacitly on trial beside Mladic in The Hague is a set of ideas: in my view the left’s most disturbing case of denial and doublethink since the widespread refusal to accept that Stalin had engineered a famine in the Ukraine.

I first raised this issue a year ago, when I sharply criticised a book by two luminaries of the left, Edward Herman and David Peterson. The Politics of Genocide seeks to downplay or dismiss both the massacre of Bosniaks at Srebrenica in 1995 and the genocide of Tutsis committed by Hutu militias in Rwanda in 1994.

Their claims are extraordinary: that the cause of death of the ‘vast majority’ of the Bosniaks at Srebrenica remains ‘undetermined’; that rather than 800,000 or more Tutsis being killed by Hutu militias in Rwanda, “the great majority of deaths were Hutu, with some estimates as high as two million”, while members of the Hutus’ Interahamwe militia were the ‘actual victims’ of genocide.

What has changed since then is that the movement to which I thought I belonged has closed ranks: against attempts to challenge this revisionism, against the facts, in effect against the victims of these genocides. My attempts to pursue this question number among the most dispiriting experiences of my working life.  — The Guardian, London