In a way, we can have a much easier discussion about the future of technology than we can about why a young man kills another man in a war.

The Chinese have a long history of slaughtering each other without bothering their neighbors.

It has always struck me as the world's great fortune that the two great superpowers were the United States and the Soviet Union, who managed the Cold War with meticulous care in retrospect. Imagine the European diplomats of 1914 or 1938 armed with nuclear weapons. It is easy to believe they would not have been as cautious.

War is an extraordinary condition to be in - to be, for example, in the combat information center of a warship [and behaving] as though you were merely processing credit card applications. [Instead,] the information you're processing is that an incoming missile is 15 kilometers away, now 10 kilometers away, now 5 kilometers. You have to separate yourself psychologically from the fact that your mortal existence may well end. That is the ancient reality of war.

Constraint theory asks: What is the price for doing this? Now one way around constraint theory is declaring your enemy crazy. Crazy and stupid are not concepts used in forecasting. When people say they're really stupid or they're crazy, that's laziness. That means I don't want to think through their position or about what they're really going to do.

The British bombed German cities [during World War II] to keep the workers awake at night. So instead of dropping one bomb, we sent a thousand planes and, yes, we took out the factory sometimes, but we also took out the city. It reached the point where we wanted more efficient ways to destroy a city. The result was nuclear weapons.

Constraint theory argues a number of things. First, that the impossible has to be identified. Second, that the actor is then constrained by circumstances to act a certain way. For example, should we invade ISIS? Can we invade ISIS? What would it take to invade ISIS? Once you ask that question you discover the price of that option and then you take a look at American politics and see that the country is probably not prepared to invest the 2 to 3 million people that it would take to defeat ISIS and the insurgency afterwards. All right, so that's not going to happen.