Once again, France is reeling — after the second major terror attack upon defenseless Paris this year.

Eight fighters — all of them young EU citizens supposed to be working for ISIS, or Daesh — took 129 lives, with guns and suicide bombs, on Friday.

At the bloodiest site of the violence, the Bataclan concert hall, the shooters told their victims they were seeking revenge for French bombing of Syria. The next day, the embattled French President, François Hollande, responded to the attack with revenge of his own: a wave of new bombings in Syria, especially in Raqqa, Daesh’s capital city.

Hollande, who pushed for a Gallic “Patriot Act” this winter after the killings at Charlie Hebdo, has now proposed a series of changes to the French constitution designed to allow military action in a national state of emergency.

It’s a script we saw after Sept. 11: lock down at home, arm up abroad. With deep condolences for grieving France, we’re all wondering how this cycle of violence finally ends?

With Amb. Chas Freeman, a freethinking veteran of foreign service, and the French journalist Sylvain Cypel, we’re in the Open Source situation room, trying to see the tragic attacks in Paris and the force called Daesh in the right light, as a hellish problem with causes — and solutions.

First we asked tourists, students, and lunch-breakers on Boston Common for their theory on how to make it out of the terror age: