In a recent op-ed ("Is there another option?" June 2 ), Moshe Arens suggested that the option of one state west of the Jordan with full citizenship for all Palestinians should be given serious consideration.

The one-state solution is advocated by a number of Palestinian intellectuals and is becoming rather popular in the European left. Their reason is generally that the one-state solution would give more justice to the Palestinians, and this position is mostly seen as anti-Israeli. On Israel's extreme right, holding on to the Greater Land of Israel is also a popular position, generally held on theological grounds.

Arens raises the idea from a different standpoint, because he is a secular liberal who indeed believes in full equality for Israel's Arabs. Even though I have for years argued that the one-state solution is not feasible, Arens' idea needs to be explored, at least as a thought experiment, because it may well be that the window of opportunity for the two-state solution is about to close. So far no Israeli government has succeeded in implementing it; Palestinians are beginning to reject it, and Israel may not be able to uproot more than 100,000 settlers.

In his political career, Arens has indeed tried to increase equality for Israel's Arabs, and he deplores Israel's failure in doing so. He told me that this failure was his strongest motivation for writing the article. Thinking about this failure requires us to face the fact that Israel has been in a culture war for most of its existence - and not only with respect to Israel's Arab citizens. Israel's elections ostensibly seem to be about the Israeli-Palestinian conflict, but in reality they are a reflection of the tensions in Israeli society: religious versus secular, Ashkenazim versus Sephardim, Jews versus Arabs.

Of course, many people will not accept Arens' assessment that there are only 1.5 million Palestinians in the West Bank, and Palestinians are unlikely to accept the exclusion of Gaza from the new state. But even in Arens' scenario, Israel would de facto become a binational state. Jewish cultural hegemony would have to be largely renounced and give way to a multicultural model.

Arens' idea raises a real challenge for Israel: It would, for the first time, have to face the task of radically revising its political system and culture and to think carefully about how ethnicities, religions and worldviews can truly live side by side with each other instead of struggling for cultural hegemony.

One consequence of Arens' idea is that the state would have to sever its ties to all religious institutions, and would have to become completely secular, along the French or U.S. model. Both Jews and Muslims would have to accept that religion cannot play any role in affairs of state, and religious institutions would become completely voluntary and communitarian. To avoid tensions between the various religious groups, and between religious and secular lifestyles, the Swiss confederative model might be considered. The federal government's involvement in the cantons' internal affairs would be low to allow for maximal cultural flexibility.

Both Jews and Palestinians would have to be willing to renounce the struggle for hegemony. The political culture would have to be structured in a way that avoids such a struggle. Jews would have to be willing to accept Jabotinsky's suggestion that the president of the state could sometimes be Jewish and sometimes Arab.

Of course, the most attractive feature of the one-state solution is a complete restructuring of the Middle East. Arab rejection of a fully liberal Israel/Palestine would no longer have a case. Of course, radical Islamists might continue to object to the presence of non-Muslims, but most Arabs would feel much more comfortable with a binational state.

I continue to be skeptical about the one-state solution. I am afraid that it will be very difficult to implement, and it is almost unimaginable that a cohesive society would emerge after a century of bloody conflict, particularly if you consider that even states like Belgium are on the verge of falling apart. Economic inequality, which is very high in Israel today, would increase even further and create huge problems.

But Arens' challenge must be taken seriously. First, we are close to the point at which only the one-state solution will be possible. Second, because even if the two-state solution would finally be achieved, Israel would do well to apply some of the features of the one-state solution: to become a truly liberal, secular state without ethnic dominance in which subgroups no longer try to impose their way of life on each other. It should think about a confederative structure, because this might conceivably end Israel's current culture war.