Alison Jackson

You can watch a little bit of war from your nice living room - 30 seconds of what's going on in Syria - and when you've had enough, switch over to some celebrity programme. We live our life through screens and images in this way, and we don't know what is real or fake anymore. It doesn't matter.

Because Bin Laden's culture doesn't permit the worship of images, they understand how powerful images are. We wouldn't have thought of creating a visual bomb. In a way, he's chopped down two iconic buildings, and used our very truth imagery, to express himself. It's fascinating... I mean, dreadful.

By irreducibly complex I mean a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning.