The disclaimers of the Begin government for all responsibility in the massacres of Palestinians are not merely shameful, they are absurd.

It may be literally true that, as Israeli Defense Minister Ariel Sharon said during the impassioned Knesset debate about a commission of inquiry into the atrocity, that "no soldier or commander of the Israeli Defense Force took part in this terrible act."

But to go from to a claim that Israel has "clean hands" requires a willing suspension of disbelief that the world is not ready to give.

It requires us to consider, for instance, the possibility that the Jews are stupid. In the light of their accomplishments in all forms of human endeavor, that is an insult to their intelligence as well as ours.

The Israeli Cabinet could hardly have foreseen in grisly detail the butchery occasioned by its decision to allow the Christian Phalangist forces to enter the Sabra and Shatila refugee camps. But it did not take much wit to imagine.

As opposition leader Shimon Peres observed at the top of his voice in the tumultuous debate, "You don't have to be exceptionally wise. It's enough to be a village policeman to know what the consequences would be."

The Phalangists' record is one of Hitlerian cruelty and violence. Did Begin's Cabinet, when giving Phalangists the green light, think they would enter the camps with clipboards and name tags? Did they expect that, on request, Palestinian guerrillas would step forward?

Horrified correspondents saw the corpses of a 3-year-old boy shot in the back of the head, babies in diapers, old men, old women. These had escaped the bulldozers that the butchers thoughtfully brought with them to remove evidence of their "anti-terrorist" exertions.

Israeli military personnel passed the killers through the lines, lit the scene with flares and, despite their storied alertness, noticed nothing.

"Eyes you have, and they see not? Ears you have, and they hear not?" Peres is reported to have shouted at one point in the debate.

"We didn't know exactly what was going on," Sharon told the tumultuous inquiry.

He is trying to tell us something else we know could not be true. He is suggesting that Israeli intelligence, the best in the world, did not have agents within the camp, did not have agents among the Phalangists. This is a libel on Israeli espionage, the wizards who plotted to a hair trigger the daring rescue at Entebbe, the bombing raid on the Iraqi power plant. That magnificent organization failed at a moment when most needed -- if not for national security, surely for national honor?

The alibi of not knowing comes gratingly from Jewish lips. It was an alibi they heard during their own holocaust. They spat on it then. They treated it "with contempt" -- the phrase Begin used in his answer to what he called "blood libel," that is, accusations of Israeli complicity in the pogrom of the Palestinians.

Sharon embellished the excuse of ignorance with another preposterous claim about the Israeli military.

The Christian militia, having dispatched as many as 1,000 persons, "refused to speak about the killings to Israeli officers," he said.

The idea of Israeli officers meekly accepting "a no comment" from clients they had armed and trained is at variance with their reputation for toughness and effectiveness. The Israeli Defense Forces are the best in the Middle East; they have proved their mettle in five wars. Their uncharacteristic acceptance of what was, for all practical purposes, insubordination is another fact worthy of the formal investigation that Begin beat down in the Knesset.

And how does Sharon explain the Israeli Army's first and only failure to accomplish a mission? The army returned to Beirut to safeguard the population.

Not all Israelis are buying the government story. In fact, the country is in an uproar over the latest black chapter in its Lebanese misadventure, which Begin calls " a struggle for truth . . . a fight against international terrorism." They want to know what Begin knew and when he knew it.

The harshest criticism, the bitterest demands for investigation come from Israeli papers. Two high officials of the Begin government have resigned.

The Israelis know they have to save themselves from the opprobrium of rationalizing mass murder. President Reagan, who not long ago condoned use of U.S. arms in bombing civilians, calls for Israeli withdrawal from Beirut and is ignored. U.S. politicians and Jewish leaders wring their hands.

Israelis know that ordinary governments try to cover up massacres. Even ordinary democracies don't put up with it. For a country that promised to be "a light among nations," it won't do at all.