You see, when a tragedy like this strikes, it is part of our nature to demand explanations -- to try and pose some order on the chaos and make sense out of that which seems senseless. Already we've seen a national conversation commence, not only about the motivations behind these killings, but about everything from the merits of gun safety laws to the adequacy of our mental health system. And much of this process, of debating what might be done to prevent such tragedies in the future, is an essential ingredient in our exercise of self-government.