An armed attack on any part of the media will get plenty of media attention, so when Islamists killed 12 people at the offices of the French satirical magazine Charlie Hebdo, it was front-page news all over the world. A simultaneous attack on a kosher deli in Paris underscored the sectarian nature of the crimes.
The outrage was followed by a huge march in downtown Paris that attracted crowds estimated over a million, including 40 world leaders (though curiously, none from the United States). It was all moving and solemn, with lots of candles and placards printed "Je Suis Charlie." Solidarity is a very nice thing, but I question if anyone from ISIS or Al Qaeda in the Arabian Peninsula felt all that threatened.
Whenever evil men commit a crime like this, there's a predictable exchange. Our side: "if this happened in America, someone with a concealed pistol might have been able to stop it." Their side: "Ha! You're going to up against a terrorist with an AK using your little peashooter?"
We can argue hypotheticals all day long, but I think this debate misses the point. There are millions of concealed carriers in this county, but the odds that one will be on the scene and able to respond when an act of terrorism goes down are necessarily small. And a pistol-armed civilian would have to think long and hard about how best to confront a man with an AK.
The fact we have concealed carry is in this case more important symbolically than practically. What it says is that if you go kill some Frenchmen, the French will light some candles and carry some placards. If you try to kill an American, he just may shoot back, or someone else may shoot you on the spot. Unlike the French (who, by the way, are pretty well-armed by European standards), we own guns for protection and many of us are authorized to carry them, whether by permit or by "constitutional carry" in places like Alaska, Arizona and Vermont. When you take us on, you take on the whole people, not just the government apparatus, which in Europe has been at much greater pains to stave off a chimerical backlash against immigrant populations than to protect the native-born.
France has a huge internal security apparatus that historically has not shied from harsh measures when dealing with threats internal or external. But police leaders readily admitted they lost track of the brothers who shot the Charlie Hebdo staff; no police force is big enough to keep tabs on every possible suspect. A point is reached where security can't be left to the professionals. Everyone has to be involved, and sometimes that means carrying something more lethal than a candle.