Changes in every society can be done peacefully. The example of that was the Velvet revolution (17th November, 1989) in former Czechoslovakia. It lead to the overthrowing of the Soviet regime.
On the other hand, what happened in Paris last Friday is unexplainable. Even if someone is unhappy, it does not give him the right to shoot innocent people. So let's be peaceful, united, and strong where it is needed.