TBH I have been thinking about this since 9/11. I doubt it was that philosophical. They wanted to show that they could attack us. And they did. They had ZERO, no tech, no highly trained snipers and marines, very little funding (compare al-qaida's funding with the US Government's). It is us who did it all. We "refuse to be terrorized" but instead we give up liberties like they are tumors that we will gladly shed to increase our perceived chances of survival.