"When the truth is replaced by silence," the Soviet dissident Yevgeny Yevtushenko said, "the silence is a lie." It may appear that the silence on Gaza is broken. The small cocoons of murdered children, wrapped in green, together with boxes containing their dismembered parents, and the cries of grief and rage of everyone in that death camp by the sea can be witnessed on al-Jazeera and YouTube, even glimpsed on the BBC. But Russia's incorrigible poet was not referring to the ephemera we call news; he was asking why those who knew the why never spoke it, and so denied it. Among the Anglo-American intelligentsia, this is especially striking. It is they who hold the keys to the great storehouses of knowledge: the historiographies and archives that lead us to the why.

They know that the horror now raining on Gaza has little to do with Hamas or, absurdly, "Israel's right to exist". They know the opposite to be true: that Palestine's right to exist was cancelled 61 years ago and that the expulsion and, if necessary, extinction of the indigenous people was planned and executed by the founders of Israel. They know, for example, that the infamous "Plan D" of 1947-48 resulted in the murderous depopulation of 369 Palestinian towns and villages by the Haganah (Israeli army) and that massacre upon massacre of Palestinian civilians in such places as Deir Yassin, al-Dawayima, Eilaboun, Jish, Ramle and Lydda are referred to in official records as "ethnic cleansing". Arriving at a scene of this carnage, David Ben-Gurion, Israel's first prime minister, was asked by a general, Yigal Allon: "What shall we do with the Arabs?" Ben-Gurion, reported the Israeli historian Benny Morris, "made a dismissive, energetic gesture with his hand and said, 'Expel them'".

The order to expel an entire population "without attention to age" was signed by Yitzhak Rabin, a future prime minister promoted by the world's most efficient propaganda as a peacemaker. The terrible irony of this was addressed only in passing, such as when the Mapam party co-leader Meir Ya'ari noted "how easily" Israel's leaders spoke of how it was "possible and permissible to take women, children and old men and to fill the road with them because such is the imperative of strategy. And this we say . . . who remember who used this means against our people during the [Second World] War . . . I am appalled."

Every subsequent "war" Israel has waged has had the same objective: the expulsion of the native people and the theft of more and more land. The lie of David and Goliath, of perennial victim, reached its apogee in 1967 when the propaganda became a righteous fury that claimed the Arab states had struck first against Israel. Since then, mostly Jewish truth-tellers such as Avi Shlaim, Noam Chomsky, Tanya Reinhart, Neve Gordon, Tom Segev, Uri Avnery, Ilan Pappé and Norman Finkelstein have undermined this and other myths and revealed a state shorn of the humane traditions of Judaism, whose unrelenting militarism is the sum of an expansionist, lawless and racist ideology called Zionism. "It seems," wrote the Israeli historian Pappé on 2 January, "that even the most horrendous crimes, such as the genocide in Gaza, are treated as discrete events, unconnected to anything that happened in the past and not associated with any ideology or system . . . Very much as the apartheid ideology explained the oppressive policies of the South African government, this ideology - in its most consensual and simplistic variety - allowed all the Israeli governments in the past and the present to dehumanise the Palestinians wherever they are and strive to destroy them. The means altered from period to period, from location to location, as did the narrative covering up these atrocities. But there is a clear pattern [of genocide]."

In Gaza, the enforced starvation and denial of humanitarian aid, the piracy of life-giving resources such as fuel and water, the denial of medicines, the systematic destruction of infrastructure and killing and maiming of the civilian population, 50 per cent of whom are children, fall within the international standard of the Genocide Convention. "Is it an irresponsible overstatement," asked Richard Falk, UN special rapporteur for human rights in the occupied Palestinian territories and international law authority at Princeton University, "to associate the treatment of Palestinians with this criminalised Nazi record of collective atrocity? I think not."

In describing a “holocaust-in-the making”, Falk was alluding to the Nazis’ establishment of Jewish ghettos in Poland. For one month in 1943, the captive Polish Jews, led by Mordechaj Anielewicz, fought off the German army and the SS, but their resistance was finally crushed and the Nazis exacted their final revenge. Falk is also a Jew. Today’s holocaust-in-the-making, which began with Ben-Gurion’s Plan D, is in its final stages. The difference today is that it is a joint US-Israeli project. The F-16 jet fighters, the 250lb “smart” GBU-39 bombs supplied on the eve of the attack on Gaza, having been approved by a Congress dominated by the Democratic Party, plus the annual $2.4bn in warmaking “aid”, give Washington de facto control. It beggars belief that President-elect Obama was not informed. Outspoken about Russia’s war in Georgia and the terrorism in Mumbai, Obama has maintained a silence on Palestine that marks his approval, which is to be expected, given his obsequiousness to the Tel Aviv regime and its lobbyists during the presidential campaign and his appointment of Zionists as his secretary of state and principal Middle East advisers. When Aretha Franklin sings “Think”, her wonderful 1960s anthem to freedom, at Obama’s inauguration on 20 January, I trust someone with the brave heart of Muntader al-Zaidi, the shoe-thrower, will shout: “Gaza!”

The asymmetry of conquest and terror is clear. Plan D is now "Operation Cast Lead", which is the unfinished "Operation Justified Vengeance". This was launched by Prime Minister Ariel Sharon in 2001 when, with George W Bush's approval, he used F-16s against Palestinian towns and villages for the first time.

Why are the academics and teachers silent? Are British universities now no more than “intellectual Tescos”?

In that same year, the authoritative Jane's Foreign Report disclosed that the Blair government had given Israel the "green light" to attack the West Bank after it was shown Israel's secret designs for a bloodbath. It was typical of new Labour's enduring complicity in Palestine's agony. However, the Israeli plan, reported Jane's, needed the "trigger" of a suicide bombing which would cause "numerous deaths and injuries [because] the 'revenge' factor is crucial". This would "motivate Israeli soldiers to demolish the Palestinians". What alarmed Sharon and the author of the plan, General Shaul Mofaz, then Israeli chief of staff, was a secret agreement between Yasser Arafat and Hamas to ban suicide attacks. On 23 November 2001 Israeli agents assassinated the Hamas leader Mahmoud Abu Hanoud and got their "trigger": the suicide attacks resumed in response to his killing.

Something uncannily similar happened on 4 November last year when Israeli special forces attacked Gaza, killing six people. Once again, they got their propaganda "trigger": a ceasefire sustained by the Hamas government - which had imprisoned its violators - was shattered as a result of the Israeli attacks, and home-made rockets were fired into what used to be called Palestine before its Arab occupants were "cleansed". On 23 December, Hamas offered to renew the ceasefire, but Israel's charade was such that its all-out assault on Gaza had been planned six months earlier, according to the Israeli daily Haaretz.

Behind this sordid game is the "Dagan Plan", named after General Meir Dagan, who served with Sharon during his bloody invasion of Leba non in 1982. Now head of Mossad, the Israeli intelligence organisation, Dagan is the author of a "solution" that has brought about the imprisonment of Palestinians behind a ghetto wall snaking across the West Bank and in Gaza, now effectively a concentration camp. The establishment of a quisling government in Ramallah, under Mahmoud Abbas, is Dagan's achievement, together with a hasbara (propaganda) campaign, relayed through mostly supine, if intimidated western media, notably in the US, which say Hamas is a terrorist organisation devoted to Israel's destruction and is to "blame" for the massacres and siege of its own people over two generations, since long before its creation. "We have never had it so good," said the Israeli foreign ministry spokesman Gideon Meir in 2006. "The hasbara effort is a well-oiled machine."

In fact, Hamas's real threat is its example as the Arab world's only democratically elected government, drawing its popularity from its resistance to the Palestinians' oppressor and tormentor. This was demonstrated when Hamas foiled a CIA coup in 2007, an event ordained in the western media as "Hamas's seizure of power". Likewise, Hamas is never described as a government, let alone democratic. Neither is its proposal of a ten-year truce reported as a historic recognition of the "reality" of Israel and support for a two-state solution with just one condition: that the Israelis obey international law and end their illegal occupation beyond the 1967 borders. As every annual vote in the UN General Assembly demonstrates, most states agree. On 4 January, the president of the General Assembly, Miguel d'Escoto, described the Israeli attack on Gaza as a "monstrosity".

When the monstrosity is done and the people of Gaza are even more stricken, the Dagan Plan foresees what Sharon called a "1948-style solution" - the destruction of all Palestinian leadership and authority, followed by mass expulsions into smaller and smaller "cantonments", and perhaps, finally, into Jordan. This demolition of institutional and educational life in Gaza is designed to produce, wrote Karma Nabulsi, a Palestinian exile in Britain, "a Hobbesian vision of an anarchic society: truncated, violent, powerless, destroyed, cowed . . . Look to the Iraq of today: that is what [Sharon] had in store for us, and he has nearly achieved it."

Dr Dahlia Wasfi is an American writer on Iraq and Palestine. She has a Jewish mother and an Iraqi Muslim father. "Holocaust denial is anti-Semitic," she wrote on 31 December. "But I'm not talking about the World War II, Mahmoud Ahmadinejad [the president of Iran] or Ashkenazi Jews. What I'm referring to is the holocaust we are all witnessing and responsible for in Gaza today and in Palestine over the past 60 years . . . Since Arabs are Semites, US-Israeli policy doesn't get more anti-Semitic than this." She quoted Rachel Corrie, the young American who went to Palestine to defend Palestinians and was crushed by an Israeli bulldozer. "I am in the midst of a genocide," wrote Corrie, "which I am also indirectly supporting, and for which my government is largely responsible."

Reading the words of both, I am struck by the use of "responsibility". Breaking the lie of silence is not an esoteric abstraction, but an urgent responsibility that falls to those with the privilege of a platform. With the BBC cowed, so too is much of journalism, merely allowing vigorous debate within unmovable, invisible boundaries, ever fearful of the smear of anti-Semitism. The unreported news, meanwhile, is that the death toll in Gaza is the equivalent of 18,000 dead in Britain. Imagine, if you can.

Then there are the academics, the deans and teachers and researchers. Why are they silent as they watch a university bombed and hear the Association of University Teachers in Gaza plead for help? Are British universities now, as Terry Eagleton believes, no more than “intellectual Tescos, churning out a commodity known as graduates rather than greengroceries”?

Then there are the writers. In the dark year of 1939, the Third American Writers' Congress was held at Carnegie Hall in New York and the likes of Thomas Mann and Albert Einstein sent messages and spoke up to ensure that the lie of silence was broken. By one account, 2,500 jammed the auditorium. Today, this mighty voice of realism and morality is said to be obsolete; the literary review pages affect an ironic hauteur of irrelevance; false symbolism is all. As for the readers, their moral and political imagination is to be pacified, not primed. The anti-Muslim Martin Amis expressed this well in Visiting Mrs Nabo kov: "The dominance of the self is not a flaw, it is an evolutionary characteristic; it is just how things are."

If that is how things are, we are diminished as a civilised people. For what happens in Gaza is the defining moment of our time, which either grants war criminals impunity and immunity through our silence, while we contort our own intellect and morality, or it gives us the power to speak out. For the moment I prefer my own memory of Gaza: of the people's courage and resistance and their "luminous humanity", as Karma Nabulsi put it. On my last trip there, I was rewarded with a spectacle of Palestinian flags fluttering in unlikely places. It was dusk and children had done this. No one had told them to do it. They made flagpoles out of sticks tied together, and a few of them climbed on to a wall and held the flag between them, some silently, others crying out. They do this every day when they know foreigners are leaving, in the belief that the world will not forget them.