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.

I cannot understand how something as ubiquitous as war can simply be dismissed as pathological. It is not clear to me that it is an unspeakable evil. If it is, I need proof of it.

If you lose yourself to rage in the complexity of battle, you are going to be lost.

We cannot anticipate the moral circumstances under which we will live. And therefore [I refuse] to say that I will not live in a moral circumstance that requires violence.

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.

There is a radical and unprecedented shift [in war] that is part of the general transformation of civilization. First, understand that the past 150 years of warfare are totally unprecedented in that we introduced a breathtakingly inefficient technology: guns. In the First World War, and this is not an exaggeration, it took 10,000 rounds of ammunition to kill one person. Any given shot had a one in 10,000 probability of ending someone's life.

Constraint theory defines for you what outcomes are possible and what outcomes are impossible. It also eliminates wishful thinking.