Who caved? That's the question chiefly asked in the wake of the agreement reached at the Camp David summit - as if those who climbed down were inevitably losers.

But as it happens, Prime Minister Menachem Begin of Israel made tactical gains that entail strategic risks. President Anwar Sadat, without losing anything for Egypt, made tactical concessions that create big opportunities that other Arab leaders may either exploit or throw away.

Two undoubtedly short-term gains accrue to Begin. He has postponed for five years a final reckoning of the Israeli presence in the Gaza Strip and the territories on the West Bank of the Jordan, which he calls Judea and Samaria.

At the same time he has set in motion a fast process for peace with Egypt that gets moving before Christmas. Israel is almost certain to get peace with Egypt before having to address itself to any other Arab claims. Perhaps events will create a separate peace between Israel and Egypt.

Sadat yielded nothing that was important to Egypt. He secured return of the whole Sinai desert to Egyptian sovereignty. He got the airfields the Israelis wanted to hold. Even the Jewish settlements will almost certainly be erased.

The quick peace that he set out to achieve on his visit to Jerusalem last year will be as much to his advantage as to the advantage of Begin. "I didn't start this," he said at the Egyptian embassy the other day, "to stop in the middle."

To be sure, Sadat has climbed down from positions staked out earlier on behalf of other Arabs. He has not achieved advance Israeli agreement to withdraw from all occupied Arab lands. He has not attained prior agreement to a Palestinian state.

But he has wrung from Begin significant practical concessions on the future of the West Bank and Gaza. The Israeli military occupation is to be dismantled - apparently in a matter of months. Some Israeli forces are to be pulled back to Israel, and others are to be shuffled onto specified "security zones."

The Palestinians are allowed to create in the West Bank and Gaza a mechanism for self-rule with full autonomy. They will participate, at the end of the five-year transition, in the decision on ultimate sovereignty over the West Bank and the Gaza Strip. Jordan is invited to join Israel in stationing a security force on the West Bank, and Egypt will have a role on security in the Gaza Strip. Moreover, the whole spirit of the agreement emphasizes "transfer of authority" from Israel to the Arabs.

More of the states in the world achieved independence on a skimpier base than that. If they were clever, the Palestinian Arabs would take advantage of the Camp David rules. They would establish a local government with full autonomy. They would enter into good relations with the Egyptians and Jordanians.

They would tap the Saudis for money and the Russians for diplomatic support. They would maintain existing ties with the exile groups, especially the Palestine Liberation Organization. Then when the day came, five years hence, they would hold most of the cards.

They wuld be in control politically on the ground. They would have overwhelming international support. Israel would be isolated, clinging only to a piece of paper and a small, segregated occupation force. An independent Arab state would be inevitable.

The probability is that the Arabs will not realize those possibilities. They are badly divided. The PLO has already denounced the Camp David agreement. It is questionable whether Jordan's King Hussein will come in. The Saudis show signs of hanging back.

No doubt Begin will be out of office when the time of reckoning comes five years from now. Still, it is surprising to find the Israelis congratulating themselves so fulsomely for their performance at Camp David. If they feel so good now, it is only because the Carter adminstration has - for the moment - stopped hitting them on the head. If they escape without a Palestinian state on the West Bank, it is only because the Arabs will have missed the chance once again.

At best, Begin got out of a tight corner at Camp David. But the man who achieved the long-term gains, the large figure in the Mideast today, remains Anwar Sadat.