Two versions of last week’s events in Gaza, the pessimist’s and the optimist’s, are currently vying with each other. The pessimist’s version goes:

The Hamas takeover of Gaza is a major blow to any possible Israeli-Palestinian peace agreement and to the international war against terror. A new terrorist state has been born — one that not only will oppose any détente with Israel, but will be part of a global constellation of anti-American Islamic radicalism, alongside Iran, Al Qaeda, the insurgents in Iraq, the Taliban in Afghanistan, Hezbollah in Lebanon, etc. Hamas will now work to destabilize other Arab regimes in the area, especially the Palestinian Authority in the West Bank. It’s bad news, anyway you look at it.

The optimist’s version goes:

On the contrary, it’s good news. As long as Hamas was part of the Palestinian Authority, the PA was paralyzed in terms of its ability both to govern its own population and to put an end to anti-Israel terror and enter into serious peace negotiations with Israel. Now, with Hamas in power in Gaza but out of the picture in the West Bank, things have been greatly simplified from Israel and America’s point of view. On the one hand, the small enclave of the Gaza Strip is now a hostile state that can be treated as such, whatever humanitarian aid may have to be supplied to its inhabitants. On the other hand, the larger and more strategically important West Bank is now totally under the control of Mahmoud Abbas and his pro-Western Fatah moderates — who, freed of the need to placate Hamas and cooperate with it, can, with American and Israeli support, finally stamp out terror and negotiate.

Who is right?

Well, not necessarily one or the other. It’s not quite as simple as either the pessimists or the optimists makes out.

The pessimists exaggerate the dangers of a Hamas state in a tiny area barely 20 miles long and between five and eight miles wide. Bordered by Israel to the north and east, Egypt to the south, and a sea blockadable by the Israeli navy to the west, such a “Hamastan,” as it is being called by Israeli commentators, could not easily be integrated into any radical Islamic network, much less form an important link in it.

Without Israel or Egypt’s consent, no one can enter Gaza or leave it, much less bring weapons or trainers of terror in or out of it, or use it as an international base. And even if Iran and other radical Muslim countries wished to turn Hamastan into a client state, there would be no way for them to feed its hungry population or offer it significant assistance. If ever there was a containable geopolitical problem, it is this one.

But the optimists exaggerate, too. The West Bank without Hamas – “Fatahland,” as some of the same commentators have been referring to it — is still not Luxembourg. A plurality of its population voted for Hamas in the 2006 elections, and within Mr. Abbas’ undisciplined and disorganized Fatah, too, there are significant elements that are closer to Hamas in their attitude toward Israel than they are to the moderates in their own party.

Moreover, even if these moderates can really run the show and clamp down on terror, in return for which Israel can let up on security restrictions and release frozen Palestinian funds, this does not yet mean fruitful peace negotiations.

In order to negotiate, it is not enough to have someone to talk to; you also must have something to talk about. If the Fatah moderates continue to demand a total or near-total Israeli return to the 1967 borders, negotiations will never get anywhere.

In the final analysis, the overall positive or negative outcome of the events in Gaza will be determined not so much by the policies of Israel and America as by those of Hamastan’s and Fatahland’s Arab neighbors, Egypt and Jordan. If ever there was a moment in which these two countries could step in and play a constructive role in helping to solve the Israeli-Palestinian conflict, it is now. If ever there was a moment in which they could flub the opportunity, it is now too.

Egypt, which has done little to seal off the Gaza Strip until now from massive weapons and explosive smuggling, and nothing at all to alleviate the economic plight of its 1.4 million largely impoverished Palestinians, can do both by policing its border with Gaza seriously at the same time that it opens it to commercial and human traffic.

Jordan, which has refused to assume any political responsibility for the fate of the Palestinian territories and their inhabitants ever since King Hussein gave both a bill of divorce 20 years ago, can step back into the picture by reviving the idea of a Jordanian-Palestinian political confederation.

Only such a confederation can give the West Bank the political stability, economic opportunities, and physical hinterland that it needs, and only it can cede to Israel the major “settlement blocs” in which close to 200,000 Jews now live.

Though larger than the Gaza Strip, the West Bank is itself a small area of barely 2,500 square miles. The area of Jordan is 34,000 square miles. A federation of 36,500 square miles can afford to yield a few hundred of them to 8,000-square-mile Israel. A West Bank state alone cannot.

There are many reasons why neither Egypt nor Jordan wish to get involved in a Palestinian hornet’s nest that has generally done nothing but sting those who approach it. But if they, and the Arab League that has asked them to represent it in furthering the so-called “Saudi initiative,” are serious about peace with Israel, they will have to take the risk of getting stung. It is not only Israel, after all, that must be asked to run risks for peace.

Mr. Halkin is a contributing editor of The New York Sun.