This is about Israel/Palestine, not California. The usual liberal proposal is that the current Israel, including the West Bank and Gaza, should be divided into an Israeli/Jewish state and a Palestinian/Arab state. Supposedly, this will give both sides what they want. I’m not sure that’s true. I suspect a lot of Israeli Jews are perfectly fine with sharing their country with Palestinian Arabs, so long as the Arabs are OK with sharing the country with them, and are perfectly willing to have Jews and Arabs have totally equal rights, rather than the kind of Jewish preferences that now exist in Israel.
On the other hand, it’s very clear that there are some Palestinian Arabs that want nothing to do with anything Jewish, and some Israeli Jews who want nothing to do with anything Arab. It seems the way to accommodate all three groups is to have three states instead of two: One totally Arab/Palestinian, one totally Jewish, and one for both Jews & Arabs. It also seems to me that the way to decide on how big each state would be is to have a plebiscite for residents of the entire Israel/Palestine area where people could choose which of the three states they’d prefer to live in. The size of the states would depend on the number of votes that state got.
The three states would all have to agree that all citizens of all three states would have certain minimum human rights (e.g., right to hold property, right to vote, right to education & healthcare, right to practice one’s religion, right to trial by jury, etc.) but beyond that, the all-Arab and all-Jewish states would be allowed to have a state religion that would be given preferential treatment and citizens with that religion might, to the extent allowed by the basic human rights, also be given preferential treatment and religious laws could be, by majority vote, made binding on the entire population (again, within the framework of basic human rights).
The Arab/Jewish equality state, by contrast, would have additional constitutional provisions forbidding establishment of a favored religion, requiring equal treatment of all citizens, regardless of religion (or lack thereof) etc. Further, all three states would be required to allow free immigration/emigration between the three states (conditioned on ensuring security of borders and prohibition on transporting firearms or other weapons between the states). All three countries would also have to be open to inspection by an international body charged with ensuring that weapons aimed at attacking another state would not be available.
My guess is that the “middle” state would get the lion’s share of both Jews and Arabs. There would obviously need to be a way to have a fair partitioning and/or sharing of resources (especially water), and some areas, like Jerusalem, would probably need to be under international control, because I’d bet that all three countries would demand that it be included in their area.
Of course, this is probably just as much pie-in-the-sky as any other proposed solution, but at least it seems a bit more realistic than the two state solution being proposed by the U.S.