Menachem Begin presents the case of a paradox familiar in political life but often misunderstood. He possesses the power of weakness.

Personally, politically and in international matters, he stands so close to the edge that the merest shove could send him over. But the troubles apt to dog those who shove are so great that they prefer to let him expire.

Physically, Begin shows few signs of the heart disease and stroke that have assailed him in the past few years. He rises early and works a full day. His reading capacity, once slightly impared, is back to normal. Though his voice has weakened to the point that puts great oratory beyong him, he remains quick in the cut and thrust of debate.

Intellectually, though, something has happened. Begin speaks of peace with Egypts as if it were over and done. He talks in the narrowest way of the other part of the bargain -- "full autonomy" for the Palestine Arabs. He plans settlements -- even though there are no settlers -- to divide the territory inhabited by them into unmanageable bits and pieces. He closes off avenues for a deal with King Hussein that would fit a Palestinian entity safely under the wing of Jordan. He courts the enmity of the world in a way that threatens to make Israel a pariah state.

Why? My impression is that he is only belatedly awakened to the full implications of the deal he cut at Camp David. With his end in sight, he struggles all the harder to maintain the peace treaty while holding back on the autonomy part of the bargain. The more so as he is persuaded that those most likely to follow him -- Defense Minister Ezer Weizman or former prime minister Shimon Peres of the Labor opposition -- would sell the pass.

Politically, the transfer of authority looks like child's play. Of the 120 seats in the Israeli parliament, only 65 are in the hands of Begin's governing coalition. At least two of the coalition parties -- the Liberals, including Weizman, with a score of votes; and the Democrats, led by Deputy Prime Minister Yigal Yadin, with five votes -- are hostile to Begin's policies.

But except for Weizman, the Liberals are all afraid to jump ship. They fear they would be saddled with the blame for Israel's desperate economic plight and suffer horrendous losses in the elections precipitated by the ouster of Begin. As to the Democrats, they have argued that their presence in the government softens the prime minister's harsh line. If they quit, they would have no rationale to put before the voters in the new elections. So the very fragility of the coalition sustains it in office, and it is hard to see Begin voted from office -- except under the force of outside pressure.

The United States, as the great supplier of weapons and money to Israel, is the obvious candidate. Virtually everybody affected by events in the Middle East is now urging Washington to put pressure on Begin. But Jimmy Carter finds himself in awkward position to crack down to the point of forcing the Begin government from office. Not just because of the votes from supporters of Israel that he needs for reelection, either.

More important still, he needs marks of success in foreign policy. The affair of the Iranian hostages has been a highly visible disaster. He has been unable to muster significant pressure against the Soviet invasion of Afghanistan. Radicals look as though they might take over in Central America.

The one foreign policy success the president can begin to claim is Egyptian-Israeli peace treaty. It is asking a lot for a president to expose his one success to the shocks that would be bound to develop if Begin were ousted now.

Especially since there is no readily available alternative to the Egyptian-Israeli peace process. The leader of Britain and France and West Germany may toy with the idea of a "European initiative." Various Middle Eastern rulers may propose an "Arab alternative." But the fact is that all the alternatives move quickly to a scene that includes the Soviet Union. However, at this juncture -- with Afghanistan still burning and opportunities for Russia beckoning in the Persian Gulf -- the last thing Washington can do is make a deal with Moscow.

So weakness -- personal, political, international -- constitutes a potent prop for Begin. Like it or not, the great trick in Middle Eastern diplomacy is to keep the peace process in play until the present Israeli parliment reaches the end of its term in 1981. It is a matter of outwaiting Begin.