To tune in the evening news is to watch as Israel turns itself into something even its friends cannot defend: a country willing -- even eager -- to use deadly force to put down rioting Palestinians, more than 50 of whom have been killed in recent weeks.

It is a gruesome spectacle: embarrassing to American Jews, hate-inspiring to Arabs and utterly dismaying to all who care about either justice or peace. Israel is almost willfully transforming itself into the South Africa of the Middle East.

And without even South Africa's justification. White South Africans can at least make the mathematical argument that to grant citizenship rights to the country's black majority is to threaten the ruling white minority. Israelis, who vastly outnumber the Palestinians, can make such an argument only by deliberately blurring the distinction between Arabs generally and Palestinians in particular.

This they have tried to do. They point to three Arab-Israeli wars (all won by Israel), to unrecanted Arab vows to demolish Israel as a state, even to the exploitation of the Palestinians' plight by other Arabs, for their own cynical purposes.

It's all true, but mostly irrelevant. The burning issue of the moment is not the bad blood between Israel and its Arab neighbors but Israel's treatment of the stateless Palestinians.

It is true that other Arab nations, many of them rich from oil revenues, could take in the disfranchised residents of Gaza and the West Bank and the dreadful refugee camps. It is also true that the black nations of Africa and the West Indies could take in the disfranchised black South Africans and the residents of Crossroads and other squatters' camps. But nobody seriously suggests that as a solution to apartheid. The South African blacks have a right to political and human rights in the land of their birth and residence. So do the Palestinians.

It is true that it is difficult to find a humane way to cope with the rock-throwing, fire-setting rioters of the West Bank and Gaza -- as difficult as figuring out how to deal with rioters in Soweto or Crossroads.

The fact is, no solution is possible if you begin with the riots. The place to begin is with the situation that produced the riots and the enduring bitterness: the statelessness of a people whose homeland now is called Israel. Indeed, the recent violence began with Israel's decision to "deport" a Palestinian activist.

It is even true that Israel wants peace (or, at any rate, tranquility), though it refuses to negotiate with the Palestinians' chosen representative -- the Palestine Liberation Organization -- because the PLO has not been willing to grant the right of Israel to exist. It is like the refusal of South Africa to recognize the exiled African National Congress because it won't renounce violence.

Israel justifies its inhumane treatment of Palestinians on the ground of national security. The truth is, Israel can have no security without the military and financial backing -- some $3 billion a year -- of the United States. For all the touted influence of the American "Israel lobby," that backing requires for its continuation a minimum level of decency and fairness on the part of Israel.

Decency and fairness are what are most obviously missing on our TV sets. We see children throwing stones at soldiers and being answered with bullets and beatings. We learn of the denial of basic rights on a par with what is happening in South Africa and hardly anywhere else in the world. And we see with our own eyes what happens to children -- be they in Beirut, Soweto or the West Bank -- who are brutalized and hopeless.

South Africa, aware of the power of television to render hopelessness graphically, has tried to silence the outraged world by shutting off the TV cameras. Israel tries to accomplish the same thing by closing its ears to outside protest.

Neither tactic can work. The time is past due for both countries to enter into negotiations with the accepted representatives of its disfranchised citizens.

With regard to Israel, the most hopeful recent signal is the willingness of American Jews to speak out -- and strongly -- against present Israeli policy. The message: You must not mistake our support for a blank check; you have to change.

If the Reagan administration can muster as much courage as the American Jews have displayed, the situation in the Middle East may well be on its way to solution.

And not a day too soon.