It's too early to learn all the possible lessons -- and there will be many -- from the current turmoil throughout the Middle East, but one important lesson is that there is only one democracy that the United States can always count on to remain a strong ally. That democracy is Israel. No one knows whether any or all of the Arab states that are currently in flux will pull an "Iran" on us -- turning from friend to foe in the blink of an Ayatollah.
The optimists are hoping for more of a Lebanon than an Iran, but even Lebanon -- with a better history of democracy than any other Arab country -- is now essentially in the hands of Hezbollah. The United States cannot count on the new Egypt remaining an ally, even with the carrot of massive aid.
Some of the blame for this uncertainty falls on us for supporting friendly dictators, from the Shah to Hosni Mubarak to King Abdullah, but the reality is that the United States simply cannot rely on the increasingly vocal Arab street to support our interests. That is precisely why we have, rightly or wrongly, felt the need to cozy up to Arab tyrants who falsely promise us stability in exchange for financial and military support.
Not so with Israel. But the pressing question remains: Will the United States reciprocate, or will we be a fair-weather friend to our stalwart ally?
So far, we've been principled enough to reciprocate. United States administrations may prefer some Israeli electoral outcomes to others. We may prefer certain Israeli leaders over others. But in the end, we recognize that Israel is a stable democracy that does not need propping up from the outside.
The military aid we give Israel is not designed to protect a regime against its own citizens, as it is with regard to the aid to Jordan and Egypt. Our assistance to Israel is calculated to protect it from external enemies like Iran, sworn to its destruction.
The people of Israel may not love a particular American President or administration, but they love America and what we stand for. And Israel helps America -- with intelligence gathering, development of military weapons, cybertechnology defense and in numerous other ways. The relationship is a model of symbiosis.
But recent events in the Mideast, particularly the haste with which we abandoned Mubarak, our most loyal Arab ally, has raised questions among some Israelis as to whether Israel can always count on the United States.
Skeptical Israelis wonder how this, or any other, American administration would react to a demand from the Arab street across the entire Middle East or the United States to abandon Israel. This demand could come even if Israel makes peace with the Palestinians and agrees to permanent borders, since Islamic radicals don't recognize Israel's right to exist within any borders. Israelis recall how quickly we abandoned the shah and how responsive our government has been to the demands of protesters in Tunisia and Egypt.
Israelis wants real democracy among its Arab neighbors, but they fear that elections alone -- particularly elections that put groups like Hamas, Hezbollah and the Muslim Brotherhood in power -- will produce anything but real democracy. Hamas' violent takeover in Gaza provides the negative model that they fear will emerge from the Egyptian chaos.
While recognizing the enormous difference between democratic Israel and the tyrannical regimes against which the Arab street is now rising, these concerned Israelis are contemplating a worst case scenario. They fear that history has shown that a friend in desperate need is a friend often betrayed by superpowers.
This skepticism is not necessarily fueled by any criticism of the United States, but rather by a realistic recognition that America has its own national interests which it will always place over the interests of even its staunchest allies. The United States is, for better or worse, the world's most important superpower, and it must necessarily serve as a kind of policeman to the entire world.
Most Americans believe that it will always be in America's interests to support Israel because of its commitment to values akin to our own. But there are some Americans -- from those on the extreme right like Sen. Rand Paul, to so-called realists like Stephen Walt and John Mearsheimer, to those on the extreme left, like Noam Chomsky -- who would see no problem in abandoning Israel at the drop of a keffiyeh.
Accordingly, though most Israelis believe that America will always support its survival, many refuse to count on it. That's why they developed a long term strategy of self-reliance. The attitude of many Israelis can perhaps best be summed up by the important lesson Elie Wiesel has taught all Jews to learn from the Holocaust: "Always believe the threat of your enemies more than the promises of your friends."
The threats being made by the Muslim Brotherhood to destroy the Jewish state by force must be taken seriously. The promises by the United States to stand behind Israel, though I believe they will remain true, must necessarily be viewed skeptically by Israelis. Israel must always be prepared to defend itself.
Dershowitz, a professor at Harvard Law School, is author of "Trials of Zion."