The irony of ethnic identity
One would think the Israeli-Palestinian conflict was rooted in ethnicity differences, but Bashir's story doesn't include that as a driving force. Rather, Bashir is angry that a new government came so violently and tactlessly. The whole enterprise was doomed from its inception, not because of some problem between Jews and Arabs (in many places they have coexisted together for literally thousands of years). The problem really was that the Palestinians were treated with contempt, and had everything stolen from them, literally.
The ironic host
When Dalia invites Bashir in, he hesitates, noticing the irony of their situation. He came to Al-Ramla to mourn the loss of his childhood, and instead, he finds someone who will challenge his grudges against the Israelites. Dalia reminds Bashir that there is no reason for individuals to mistreat each other or to be driven against each other because of their political views.
The irony of terrorism
When people commit acts of terrorism, the saddest part is that sometimes it works. Bashir both commits acts of terrorism, and then he holds grudges when Jewish people treat him with hostility. The hostility comes from the willingness on either side to do violence. Such a willingness makes everyone paranoid, and it's a surefire way to bring about conflict. Terrorism is the wrong answer for Bashir, not because his anger is not founded, but because it's contrary to his purposes to be violent. His plan to open a school for integrated students is far more effective.
The ironic death of the lemon tree
For a symbol of hope to be the title of the novel, is ironic in the case that the tree dies. But that's exactly what happens: Bashir's father plants a lemon tree as a sign of God's blessing, because it brings fruit each year, and because it has an obvious yearly cycle. But then, when Dalia's family moves in, the tree dies over the years. The symbol is not that the hope has died, but rather, it was a sign created by the Palestinian family alone, and now, since their community is blended, they should create a new, better sign for hope. They make the school.
The ironic school
Dalia and Bashir (not unlike the Israelites and the Palestinian Arabs in general) are constantly fighting over the same house. In the end, no one gets it, ironically, because they choose to make the home into a school with both Jewish kids and Palestinian Muslim kids. This decision is like saying, "If our generation can't live peacefully, maybe we can teach our kids to do it." This is an ironic solution because it goes against both party's specific wishes (they'd rather live there), but it is also a true sign for hope.
