AP Photo

IN his speech in Cairo yesterday, President Obama acknowledged an important principle: “Elections alone do not make true democracy.” That principle will be tested this weekend when the Lebanese people go to the polls. Many have called for the elections to be free and fair. But few have asked whether this is even possible if Hezbollah — the radical Shiite party with a huge arsenal and a deeply anti-democratic agenda — is viewed as a legitimate participant in the process.

A similar question arose before Hamas’s participation in the 2006 Palestinian Authority elections. Then, as Israeli justice minister, I tried in vain to persuade the international community that to promote democracy it was not enough to focus on the technical conduct of elections, it...