It is not often that Europe has the chance to play a pivotal role on the world stage. But as the Palestinians push for recognition as a state at the United Nations later this month, the European Union is finding itself courted by each side, and therefore more influential on the Middle East process than at any time since the Oslo Accords.

As ever, the biggest challenge facing the E.U.’s 27 member states is presenting a unified front. There are 10 compelling reasons for them to coalesce around a “yes” vote and keep the two-state approach to Middle East peace alive.

The critical vote is likely to be in the General Assembly, on a resolution to upgrade the Palestinians’ status from observer to non-member state. The Palestinians are likely to get a majority, but what matters more than the outcome of the vote is its size and composition.

The Israeli government is lobbying hard for a “no,” and the P.L.O., unable to significantly shape realities on the ground, hopes to at least show some diplomatic traction for its continued faith in the two-state approach. Europeans find themselves in the unusual position of being the key prize in this tussle.

The first reason why the E.U. 27 should vote “yes” is that the U.N. resolution is an attempt to keep the two-state solution alive. This solution is under attack from the steady expansion of Israeli settlements in the occupied territories, and from Prime Minister Benjamin Netanyahu’s belief that the conflict should now be accepted as “insoluble.” As a result this vote is not a meaningless distraction, but a reaffirmation that the peace process is meaningful.

The second reason for a European “yes” is that the Europeans have already invested hugely in the two-state solution that is under scrutiny, including the annual €1 billion aid to help build a functioning Palestinian state. Again, a “yes” is a reaffirmation that the project is worthwhile and can succeed.

The third reason for a “yes” is simply to respond positively to Mahmoud Abbas’ state-building achievements. Failing to vote “yes” would be to respond to demands for state-building by refusing to formally acknowledge where they have got to.

The fourth reason is about the Arab Spring. Anything other than a “yes” would expose Europeans to charges of double standards from both post-revolutionary governments and conservative Arab regimes (for different reasons) for failing to support rights for Palestinians while advocating them elsewhere.

Usefully, a “yes” also aligns European interests with European values (the fifth reason), as it resets regional relationships. Interests — including preventing jihadist terrorism, containing Iran, security energy supplies and retaining markets for our exports — would all be damaged by perceived hypocrisy on the Israel/Palestinian conflict.

Despite concerns from Atlanticists that a “yes” will damage relations with the United States, arguably it could also be in Washington’s interests (the sixth reason). The U.S. is unable to vote “yes” for evident domestic reasons, but the E.U. 27 doing so would strengthen America’s hand when dealing with Israel. In the words of William Hague, a healthy trans-Atlantic relationship would be solid rather than slavish.

The seventh and eighth reasons concern Israel. The Israelis’ objections to the vote — that it is unilateral and violates previous agreements — do not hold water, and are no reason for Europe not to vote “yes.” Although the vote would open up negotiating options for Palestine that are currently closed, overall it might even help Israel. Moves toward recognition of Palestinian statehood within 1967 borders would reinforce the legitimacy of Israel’s own existence.

Despite Israeli fears, it would not necessarily open an easier path for Palestinian recourse to the International Criminal Court, and might give Europe a position from which it could pursue a quiet understanding with the Palestinians that they would not pursue I.C.C. jurisdiction for a significant period, drawing the sting from this troubling issue.

The ninth reason for a European “yes” is that it would not make Palestinian violence more likely. Indeed, a combination of perceived failure and the influence of the Arab Spring could touch off a “third intifada.” Squeezed between Israel and the invigorating sight of televised uprisings, the Palestinian authorities need a sign of progress if they are to prevent frustrations turning to violence. European endorsement of their statehood would be a powerful public signal that progress is possible.

Finally, a “yes” at the U.N. does not entail bilateral recognition of Palestine. The vote is for upgrading representation at the U.N., and only individual states can bestow recognition on Palestine.

There is of course an 11th reason for a unified European “yes” vote. The world already has enough examples of European inability to play an effective international role. Optimists will hope that Europeans will, this time, surprise us all by doing the right thing and securing themselves a much-needed diplomatic success in the process.

Martti Ahtisaari, a former president of Finland and U.N. mediator, was awarded the Nobel Peace Prize in 2008. Javier Solana is a distinguished senior fellow in foreign policy at the Brookings Institution, and served as secretary general of NATO and E.U. high representative for common foreign and security policy. Both men are members of the board of the European Council on Foreign Relations.