What can we learn from the violence? Not a damn thing. Supposedly the French riots are taking place because two morons who ran from the police tried to hide inside a powerstation and were electricuted. When you run from the police, you are responsible for your own safety. At least Americans find more plausible reasons for race riots. As much as I and everyone else like to make fun of the French, my sympathies are with them on this one.
Although I think the "no religious symbols" policy in French public schools is one that is guarenteed to increase tensions. That law should be repealed on the grounds that it is causing the exact problems that it is supposed to remedy.
Now for the Argentina riots. These riots are smaller scale than that the ones that took place in Canada in 2001. There will always be riots at trade talks so as long as a vocal and quarrelsome minority mistakely believes that free trade is not in their best interests. Everyone who does know what their economic interests are do not have time to stage counter protests because they all have full time jobs.