Last week, I had to spend some time at the new children's wing of Hadassah University Hospital in Ein Karem, Jerusalem. The hospital serves Arabs as well as Jews, and it was my impression that all its patients are treated professionally and with equality. But Arabic-language signs are almost nonexistent in this brand-new and impressive wing. The image that remains with me from the experience is of an Arab mother wandering through the halls, holding a baby connected to various medical devices, trying to find the radiology lab and asking people, in Arabic, for help, since she was unable to read the Hebrew signs.

I found the scene shocking: a major hospital in a city, one-third of whose population is Arab, with the Arab patients having to wander helplessly in search of the proper departments. Interestingly, on the ground floor where the same mother was looking for the X-ray department, there are plenty of signs, in both Hebrew and English - paying recognition to the donors who made construction of the building possible.

I thought about those same Jewish benefactors. Are they aware that the state-of-the-art structure built with their contributions doesn't have signs in Arabic? Do they think about the Arab patients and their families who aren't able to find their way around the new children's hospital?

Unfortunately, Hadassah Hospital is not alone. When it comes to signage, most public buildings in Israel - not just hospitals, but museums, government offices, sports facilities and more - allow themselves to disregard the 20 percent of the population that is Arab.

It's important that we look at the wider perspective. In Israel today there is a war over the Arabic language. Formally, it is one of the official languages of the state, but lately there have been attempts to further circumscribe the language's presence in Israel. For example, Knesset member Avi Dichter (Kadima ), with the support of dozens of his colleagues in the house, has advanced a bill that would eliminate Arabic as an "official" language of the state.

The result of all this is not just a functional or operative problem for Arab citizens or residents, like the mother in the Jerusalem hospital, but rather a clear and negative message to Arab citizens: You and your language are not wanted in the state that arose in your homeland. This space belongs to us, the Jews. The meaning of this exclusion for those of us who are Jews is no less negative: We have not succeeded in making this national home of ours, the State of Israel, a place that is tolerant and inclusive of an indigenous minority and its language.

Most Jews in Israel and in the world want the State of Israel to be Jewish and democratic, and to treat all its citizens equally. I share that desire. But there is nothing either "Jewish" or democratic in trying to make the language of a national minority disappear. On the contrary. What is required is a shared public space, where there is room for both languages. Paradoxically, the conflict over the Arabic language is today a conflict over the country's democratic nature. Nothing less than that.

Jewish philanthropy plays a central role in this conflict, whether it wants to be involved or not. I want to emphasize that it already plays a role. Just a very problematic one. This is because philanthropy supports building of many public institutions in Israel. It, therefore, must demand that every public building constructed with its funds (especially in the big cities, and in hospitals and universities ) include full and equivalent signage in Arabic. This is a modest demand that need not be costly. It's not even a demand - justified as it may be - for equal distribution of philanthropic funds to Arabs. Rather, it's a minimal condition: that in every structure paid for by philanthropic funds, all the signs appear in Arabic as well as Hebrew.

People tell me that I don't know the way philanthropy works, and that it just isn't done for donors from the Diaspora to condition their gifts on such demands. And perhaps that's correct. But one thing I do know is the nature of the relationship between Israeli Jews and Israeli Arabs, and at the moment, it is a volatile one. Every Arab child who goes with his or her parents to a children's museum (built with funds from donors ) and who feels excluded is a child whom it will be hard to convince that the State of Israel is his or her state.

This issue will be of special relevance this coming week, as many philanthropists arrive in Tel Aviv to attend the international conference of the Jewish Funders Network. Jewish philanthropists have the duty, opportunity and the privilege, to bring their influence to bear in order to end a dangerous trend, and to advance the cause of a democratic and egalitarian society in Israel. They cannot remain neutral in this struggle, because this is a struggle over the very nature of the state.