In the carnage of Gaza and the Middle East, the most unlikely people have stepped forward from their grief to offer moral leadership.

The family of Naftali Fraenkel, a 16-year-old Jewish boy who was one of three kidnapped and murdered, said in a statement after the apparent revenge killing of a Palestinian boy: “There is no difference between Arab blood and Jewish blood. Murder is murder.”

Likewise, the father of Muhammad Abu Khdeir, the Palestinian boy, said: “I am against kidnapping and killing. Whether Jew or Arab, who would accept that his son or daughter would be kidnapped and killed? I call on both sides to stop the bloodshed.”

Thus those who have lost the most, who have the greatest reason for revenge, offer the greatest wisdom. Yet, instead, it is now hard-liners on each side who are driving events, in turn empowering hard-liners on the other side.

Look, when militants in Gaza fire rockets at Israel, then Israel has a right to respond, but with some proportionality. More than 200 Gazans have been killed, three-quarters of them civilians, according to United Nations officials; one Israeli has been killed. In any case, Israel’s long-term interest lies in de-escalating, not moving to the ground war it now threatens.

Remember that the trend had been away from Gaza rocket strikes. Last year, according to the Israeli Foreign Ministry website, there were far fewer rocket strikes on Israel than in any year since Hamas took over Gaza in 2006. But then, since June, there were the kidnappings and killings, rockets and the kind of mutual escalation that arises when each side thinks that the other understands only violence.

When missiles are flying, hard-liners on each side are ascendant. They purport to be defenders of their people, but, in fact, they’ve repeatedly demonstrated myopia and taken actions that ultimately created vulnerability and weakness.

After all, it was Israel itself that helped nurture Hamas and its predecessors in the 1970s and ‘80s. The late Eyad El-Sarraj, a prominent psychiatrist in Gaza, warned Israel’s governor that he was “playing with fire” by nurturing religious militants. According to the book “Hamas,” by Beverley Milton-Edwards and Stephen Farrell, the governor replied: “Don’t worry, we know how to handle things. Our enemy today is the P.L.O.”

Similar shortsightedness unfolded to the north. The Israeli invasion of Lebanon in 1982 inadvertently helped lead to the rise of its enemy there, Hezbollah.

Likewise, it was Hamas extremism and violence after the 2005 Gaza withdrawal that undermined Israeli moderates and led to the rise of the hard-liners who today are bombing Gaza. Israel helped create Hamas, and Hamas helped created today’s Israel.

The only way out in the long run is a two-state peace agreement. It’s true that one is not achievable now, but the aim should be to take steps that make a peace deal possible in 10 years or 20 years.

Israel could learn a lesson from Britain and Spain, both of which managed to defeat terrorist challenges that were once seen as insoluble. The analogy is imperfect, for rockets weren’t falling on London or Madrid. But Spain could have sent troops to quash Basque terrorists, and Britain could have bulldozed the offices of the I.R.A.’s political wing in Belfast.

Instead, Spain gave autonomy to the Basque Country and Prime Minister Margaret Thatcher negotiated an agreement in 1985 that was criticized at the time for rewarding terrorists. This was painful and controversial, and it was by no means an instant success. Thatcher said in her memoir that the results were “disappointing.” Eventually, this approach proved transformative.

Today, in Middle Eastern terms, the analog would be a minimalist response, not a maximalist one. It would be a halt to settlements, cooperation to bolster Mahmoud Abbas and other moderate Palestinians, and an easing of the economic chokehold on Gaza to strengthen businesses there as a check on Hamas.

None of this is easy or certain. Secretary of State John Kerry’s admirable but failed peace initiative suggests that mutual distrust is so great that it may take years to lay the groundwork, so let’s get started.

When the families of a murdered Palestinian and a murdered Jew each call for humanity toward the other, it’s easy to dismiss the plea as naïve, inconsistent with harsh realities on the ground. But what we’ve actually seen for decades is that aggression on one side boomerangs and leads to aggression on the other.

In contrast, what has worked — albeit not very well and not very quickly, and in different circumstances — is the Spanish and British approaches of tough-minded conciliation and restraint to change the political landscape. That’s the approach that empowers not the hawks, but rather the Fraenkels and the Abu Khdeirs, so that an impossible peace eventually becomes possible.