The Palestinian-Israeli conflict is the single most important issue on the world agenda today.
It is a major cause of instability in an already unstable region, and a rallying point for the Arab and Islamic worlds.
No one doubts that it needs urgent resolution - but, likewise, no one has been able to resolve it.
Since 1974, the solutions on offer have all been variations on the same theme - the creation of an independent Palestinian state alongside Israel.
The Palestinian state’s parameters were never precisely defined, but a broad consensus has grown up that it would encompass the Palestinian lands occupied by Israel in 1967.
In 2002, for the first time ever, a US president gave it his clear and unequivocal support.
For a number of Palestinians (and an increasing number of Jews), however, this solution was never their preferred option.
In 1969 a Marxist PLO faction, the Popular Democratic Front, came up with a different idea - that there should be a secular, democratic state in place of Israel with equality for all its citizens irrespective of their religion or ethnicity.
But a combination of decisive rejection by a majority on both sides and military defeat at the hands of Israel persuaded the PLO to drop it and press for two states instead.
However, the idea never quite died out in some circles, and it has resurfaced in the last ten years with increasing force.
Its adherents today are still a small minority, but their numbers are growing.
Dozens of articles have appeared in the last few years discussing the single state option, and several one-state groups now exist in the US, Lausanne and London.
The shared state idea is, unsurprisingly, unwelcome to Zionists. Many Palestinians, especially those under Israeli occupation, are also unhappy with the idea, though for different reasons.
But this in itself is not a sufficient reason for dismissing it.
There are two main arguments for the unitary state - that, on the one hand, the two-state solution is no longer feasible and that, even had it been, it would not be desirable.
Israel’s colonisation of Palestinian land made a Palestinian state unrealisable, as a glance at the map of the West Bank with its colonies, bypass roads and the barrier wall being built shows.
It now houses 400,000 Jewish settlers (plus an extra 200,000 in East Jerusalem), and 80 percent of its water has been siphoned off to Israel.
When the wall is completed, about 40 percent of the land will be left in unconnected parts incapable of being formed into a state.
Colonisation of Palestinian territory has been pursued relentlessly by every Israeli government since 1967.
It is no wonder that people have started to consider the one-state option.
On the Israeli side, some have begun to fear for the future of the Jewish state, both morally and existentially.
Most of these are Zionists who argue that Israeli society is corrupted by oppressing another people, and that hatred of Israel may one day lead to its destruction at the hands of its victims.
They now speak of a bi-national state where Arabs and Jews may share the same land.
Though this will limit Zionist territorial ambitions, it will help to preserve a Jewish homeland.
For Palestinians who see no logistical possibility of a separate Palestinian state, such a solution also provides a base for Palestinian nationhood.
But even had the proposed two-state solution been logistically possible, it would not have been desirable.
It would have led to an inequitable division of the land (the Palestinian territories comprise 22 percent of the original Palestine) and could not have accommodated all the refugees who have the right to return.
It would also have enabled the survival of an exclusivist ethno-religious state that insists on its prior claim to the land and its right to punish and deprive the indigenous inhabitants.
The Palestinians’ problem is how to regain their lost land, return their refugees and build a normal life for their people.
None of these can be realised while Israel, as a Zionist, exclusivist state, remains.
The only humane, just and practical outcome is that of sharing the land between the Israelis and Palestinians already there, while allowing those who were displaced to return.
This is not the same as “throwing the Israelis into the sea”, which opponents of this idea usually claim.
Numerous objections to this solution have been raised.
Crudely, they may be summed up by saying Jews in Israel will resist the dismantling of their dreams, and the balance of power favours them. That is true - for now.
But the moral force of this solution remains and, like all issues of principle, it will outlive the shifts of politics and history.
Ghada Karmi is a Palestinian activist and writer whose latest work is In Search of Fatima (Verso, £10).