Wars are times of intense technological transformation, because societies invest - sometimes with extensive borrowing - when and where matters of life and death are at stake.

War and sex are what I call the two abysmal - by that I mean deep - parts of the human condition.

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

So you go to Brookings, or you go to Heritage or others, they know their position on any subject before they research it. If you go to an investment bank, they know what parts of the world they are going to cover and what parts of the world they are not going to cover depending on client interest. We cover the world without being skewed by that. And that makes it more valuable.

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.

What is the great fear of the United States? That an Eastern power will build a navy to challenge us. How do you keep them from doing that? Keep them at each other's throats so they don't have any money to do this. This is why we fought the First World War, the Second World War, and the Cold War.

Success looks like you sitting here pretty confident that an armed brigade isn't going to come pouring in here and blow your head off. Which I don't think is your major concern. Therefore, the United States' foreign policy is successful.