Each and every Jew who protested as a Jew against the Gaza war had a personal Jewish imperative for doing so. Some simply expressed dismay; most demanded action to end the carnage. To say that we failed is neither an expression of despair nor a statement that dissent wasn't worthwhile. Realism suggests that it was inevitable.

Let's be clear: diaspora and Israeli Jewish support for the war was extensive - and extremely dispiriting. It raises the question: critical Jewish voices may have increased, but can we ever trigger decisive change in mainstream Jewish opinion? An unsentimental look at developments may give reason for hope.

First, there's been activity in many countries and support for Jewish peace groups has increased. European Jews for a Just Peace, a 10-country federation of such organisations, reports numerous initiatives in Europe. Independent Jewish Voices, Jews for Justice for Palestinians and other UK groups demonstrated, lobbied, placed newspaper ads and joined demonstrations. IJV groups in Canada and Australia issued statements. Jewish and Israeli protesters in Toronto, Montreal and Boston occupied Israeli consulates. US peace groups have been increasingly active. Together with activity by Israeli groups, this amounts to an undercurrent of protest that is rattling establishment Jewish leadership.

Second, some groups of Jews have taken significant stands. On 11 January, the Observer made front-page news of a letter from rabbis, academics and prominent community figures at the centre of UK Jewish life, calling for a ceasefire. In Germany, a letter from 35 supporters of the group Jewish Voice for a Just Peace, demanding an end to "the murder in Gaza", was published on 17 January in the Süddeutsche Zeitung - a major newspaper in a country where expressing public criticism of Israel is difficult for anyone, let alone a group of Jews.

But most significant was the strong anti-war stand taken by J Street, the new American liberal "pro-peace, pro-Israel" lobby, which is effectively challenging the influential, rightwing Israel lobby Aipac. Heavily criticised by Rabbi Eric Yoffie, a prominent US peace camp leader, for being "profoundly out of touch with Jewish sentiment", J Street stuck to its guns and attracted increased support. It then warmly welcomed President Obama's appointment of George Mitchell as Middle East envoy, positioning itself to have clout in Washington. The positive consequences for further legitimising Jewish dissent in the US and beyond could be crucial.

Third, there are signs of underlying disquiet in the middle ground of normally solid pro-Israel Jewish opinion. On 2 January, Anshel Pfeffer wrote in Ha'aretz: "Extremely disturbed and hurt by the level of civilian deaths and destruction ... [these Jews] say, there must, there has to be another way of doing this. And they live with those doubts, often unexpressed, even among families and close friends, because the worst thing they find is that others around them don't seem to discern between the different nuances, and can't find in themselves compassion for the dead and wounded on the other side." Pfeffer is not alone in sensing this mood, which suggests Israel is perilously close to the line beyond which even some of its strongest supporters cannot go.

Two encouraging conclusions can be drawn. First, although it seems most Jews shrink from the truth and embrace the Orwellian "war is peace" propaganda, doubts are growing. For Jewish dissenters who seek an appropriate language to persuade mainstream Jewish opinion that Israel is going in the wrong direction, the effort may produce results.

Second, dissenting peace groups can be stubbornly independent and make a virtue out of minor differences. But effective coordination during the Gaza war proved empowering. It's surely worthwhile attempting to create a critical mass, united around key objectives, and expressed in language that can connect with mainstream Jewish opinion.

Israel is heavily dependent on what Jews think. Its leaders turn to their support whenever they face an internal crisis or need cover for some new military adventure. But it's now not too far-fetched to think Jewish opinion could turn decisively against Israel's current path. This would shake the government and help change Middle East realities. So, out of the rubble of Gaza and the political failure it represents, Jewish dissent may emerge a more potent force.

A final cautionary note: Jewish opposition to the Gaza war was not qualitatively different from anyone else's. And it's not more important than the horrendous experience of the people of Gaza. But were that opposition to be translated into a rolling tide of Jewish opinion, it may have a moderating influence on Israel. This would benefit Palestinians, who deserve an immediate end to siege and occupation, and Jews, who deserve an immediate end to the antisemitism, highlighted in these pages by Jonathan Freedland, which Israel's war has provoked. And ultimately lead to an Israel living in peace with its neighbours.