Now, one way of dealing with this problem is by deterrence. You don't strike first, but you have a publicly announced policy that you will retaliate savagely if you are invaded. The only thing is that it's liable to having its bluff called, and therefore can only work if it's credible. To make it credible, you must avenge all insults and settle all scores, which leads to the cycles of bloody vendetta. Life becomes an episode of "The Sopranos." Hobbes's solution, "Leviathan," was that if authority for the legitimate use of violence was vested in a single democratic agency — a leviathan — then such a state can reduce the temptation of attack, because any kind of aggression will be punished, leaving its profitability zero. That would remove the temptation to invade preemptively out of fear of them attacking you first. It removes the need for a hair trigger for retaliation to make your deterrent threat credible, and therefore, it would lead to a state of peace. Eisner — the man who plotted the homicide rates that you failed to see in the earlier slide — argued that the timing of the decline of homicide in Europe coincided with the rise of centralized states. So that's a bit of a support for the leviathan theory. Also supporting it is the fact that we today see eruptions of violence in zones of anarchy, in failed states, collapsed empires, frontier regions, mafias, street gangs and so on.