Two warriors, two nationalisms

The two men are small and awkward-looking and balding - at first sight not suggestive of the fire and fury swallowing Beirut. But that battle is largely theirs. So may be the determination of what comes next.

''They'' are Prime Minister Menachem Begin of Israel and Palestine Liberation Organization leader Yasser Arafat.

They are similar in their lifelong dedication to rival claims on the land of Palestine.

But the political challenges they face are strikingly different. So, too, are the styles of leadership these challenges produce.

Unfortunately for the victims of the latest Mideast explosion - in grisly regional tradition, most of the victims are civilians - the particular goals and qualities of each rival leader have made an inescapably volatile mix.

Menachem Begin, called in 1977 from the right-hand sideline of the Israeli political arena to the premiership, sees his own national cause and Mr. Arafat's as mutually exclusive. Period.

Mr. Begin has steadily pursued two related goals: to assure that the disputed West Bank of the Jordan River, where PLO ''moderates'' appear to want a Palestinian state, will be Israeli forever; and to use all feasible weapons to undo the PLO, particularly in light of Mr. Arafat's flirtation with compromise formulas for a dialogue with the United States.

These imperatives, say those who know Mr. Begin well, carry something close to the force of religious precepts. They are pursued with something close to Messianic fervor; also, with remarkable straightforwardness.

On the heels of his electoral victory in 1977, Mr. Begin traveled to the intended site of a Jewish settlement above Nablus, the West Bank's largest Arab town, and vowed there would be ''many more'' such outposts. ''He meant what he said,'' remarks an Israeli journalist who covered Mr. Begin for many years. ''The problem was that others didn't believe him.''

And when Mr. Begin says he sees the PLO as a bunch of murderers, when he, in effect, puts them in a category with the Nazis whose murder of Jews did much to define his world view, and when he vows neverm to talk with the PLO, it is best to assume he means it.

''I have no doubt,'' another longtime Begin-watcher elaborates, ''that he sees not the slightest discrepancy in the scale of PLO terrorism and that of a response like the invasion of Lebanon and the attacks on Beirut. . . . Once any Jewish lives factor into the equation, anything on the Arab side can be made equivalent.''

Yasser Arafat is a leader more flamboyant of image, but fuzzier of purpose. Both qualities have served him well in navigating the tides of internal Palestinian, and Arab-world, politics in the years since his fledgling Al-Fatah guerrilla group began winning the loyalty of many Palestinians bitter over the failure of both Israel and of nominal Arab allies to take up their cause.

The stubble-bearded Arafat, his holstered pistol, and his checkered headdress have also become increasingly familiar images abroad. He has won West European acceptance-in-principle of some PLO role in the Mideast negotiating process. He has built a good command of the English language and has buried an earlier uneasiness in his (habitually pre-dawn) meetings with Western reporters.

But in his contest with Mr. Begin over the future of Palestine, Mr. Arafat's leadership traits have proven decidedly less useful, some Palestinian colleagues are beginning to suspect amid the bloodletting in Beirut. One Palestinian admirer calls Mr. Arafat a consummate ''political animal.'' But his is the managerial politics of a Mayor Daley, not the visionary politics of the true statesman.

If 1977 was a key date in Israeli politics, with Mr. Begin's election, it was also central in a Palestinian context. The newly elected US President, Jimmy Carter, began to explore ways of bringing the Palestinians, and the PLO, into the search for a lasting resolution of the decades-old Arab-Israeli conflict.

Since then, through the ups and downs of the Camp David negotiating process, Mr. Arafat has increasingly faced pressure to decide an issue of overall policy long left deliberately open: whether the PLO is an engine for ''armed struggle'' in search of a return to Palestine, or for a political settlement of that claim on the basis of explicit PLO acceptance of Israel's right to exist.

Coming down on the ''political'' side of the issue has been a given prerequisite for formal dialogue with Washington. This, Palestinian moderates have argued, is essential to winning any serious pressure from the Americans on Israel, a major recipient of US aid, for a softened negotiating stand.

These moderates, some of them very close to Mr. Arafat, have held that PLO recognition of Israel's right to exist could complicate Mr. Begin's task of winning US, and perhaps eventually even domestic, backing for his views on the Palestinian issue.

Mr. Arafat has come a long way from his days as a university militant in the 1950s, or as a decidedly ''military'' leader within the early Al-Fatah. Palestinians close to him have little doubt that he, personally, sees more potential gain for Palestinian nationalism on the political front than on the military one. But should he say so explicitly?

Mr. Arafat decided not to. He concluded that ''internal constraints'' and the ''lack of a clear commitment [from the US] on an American dialogue with the PLO in return made such a plunge too risky,'' colleagues say privately.

For analogous reasons, Mr. Arafat never seriously considered signing on with the Camp David negotiating process.

Summming up the resultant complications, one prominent Arafat associate says he would have done the same thing. But he added, ''I think this is just what Begin wanted, that he hoped any but the tamest Palestinians would not join the negotiating process.''

On that score, a number of Israelis who know their prime minister agree.