I am often asked why so many Israelis are worried by the popular rebellions rocking the Middle East and why I´m so hopeful. My response is that just as their worry is tempered by hope, my hope is tempered by worry.

The worried among us fear the possibility of long-term chaos and/or the emergence of regimes even more repressive than those that are crumbling. Their arguments are serious and deserve an answer.

For decades, the free world´s policy toward the Middle East was based on the desire for stability, purchased by deals struck with leaders. That the leaders were corrupt autocrats mattered little. To the contrary, tyranny was seen as guaranteeing stability, corruption as guaranteeing that tyranny´s friendship could be bought.

This was rationalized by considerations of realpolitik and the comforting assertion that we had no right to judge the moral standards of societies different from our own.

That pact, however, has been definitively exposed as a sham, yielding not stability but its opposite. And it has been broken - not by us or the autocrats but by the peoples of the region. Their great awakening has shattered the truism that, unlike "us," they have no real desire for freedom. With tremendous courage, they have risked their lives to declare otherwise.

In that stirring spectacle lies the first, elemental reason for my hope that a historical page has at last begun to turn. But the window is only so wide, and many forces aim to shut it. So what comes next?

Surveying the fall of the dictators, some in the West have reflexively turned to other, already organized structures within the societies shaped by dictatorship: notably, the army or Islamist groups. The unspoken idea is to replicate the old pact but with a different set of players. Once again the goal is stability, rationalized now by the alleged absence of other centers of potential leadership within Arab society and by the "discovery" of moderate elements within some of the region´s worst actors.

This is delusion squared: an abdication of the free world´s ability to influence developments in the Muslim world. Take the interest expressed by Washington in "engaging" the Muslim Brotherhood. As the Egyptian democratic dissident Saad Eddin Ibrahim has put it, this is akin to announcing that the free world has no choice but to accept these people as the legitimate inheritors of power. It effectively turns a blind eye to the unprecedented opportunities of the present and repeats, obsessively, all the mistakes of the past.

There is another option: to see the region´s democratic dissidents as our real partners. How many times did I and my fellow dissidents in the Soviet Union hear the refrain: Yes, you are wonderful people - but you have no power, you command no legions. And how deep was the subsequent shock when the impossible happened and the mighty empire, with its legions and its gulag, collapsed. Who could have predicted it?

Actually, many did: those dissidents who dared to express themselves, knowing that theirs were the thoughts and feelings of tens of millions of others straining against the bonds shackling their society. With those silent armies behind them, they confidently predicted the fall of Soviet tyranny.

A lesson should have been learned but wasn´t. Many times, in later years, I heard the same arguments voiced against efforts to support democratic dissidents in Arab countries. Yet they, too, knew that their regimes were destined to fall, and said so - including directly to President George W. Bush at an international conference in Prague in 2007. They also warned that the longer the West propped up dictators, the greater the chance that, when the dictators fell, they would be succeeded by worse.

Can that fate be averted? Can the democratic reformers of the Middle East be empowered to shape a better future? It will not be easy. But - and here is my second reason for hope - circumstances are more auspicious now than they were for us in the 1980s.

Back then, we dissidents had no Internet, no CNN. The free world, for its part, had little leverage over Kremlin dictators. Today, communications are easy and instantaneous. Moreover, the Muslim Brotherhood is not yet strong enough to seize control and foreclose on genuine reform. And precisely because of their historical ties with Middle Eastern governments, the United States and the European Union are uniquely well placed to guide that process of reform.

The point of linkage is the massive foreign aid the free world has committed to these lands. By remaining generous, by mobilizing additional donors from oil-rich Arab nations, and by insisting on clear and enforceable conditions, we can help forge the building blocks of a free society: a free press, freedom of religion, the rule of law and civil-society reform. Entrepreneurs can be recruited to address the dire housing conditions in Egypt and elsewhere. International human rights organizations can prove their bona fides by working with local reformers, including trade unions and student and women´s groups. Associations like those nurtured by the Internet project Cyberdissidents can be openly strengthened.

Will we see our responsibility and our opportunity, and act? I worry that we won´t. I hope that we will. By doing so, we will purchase true stability for the peoples of the region and for ourselves.

Natan Sharansky, chairman of the Jewish Agency for Israel, spent nine years as a political prisoner in the Soviet gulag. He is the author of "The Case for Democracy: The Power of Freedom to Overcome Tyranny and Terror." (© 2011 The Washington Post Company 03/13/11)