We are already seeing a degree of instability in the world because Obama seems to have consciously wanted to step back. Donald Trump is going to be "Obama squared," a more extreme version of the same thing.

One of the things that ultimately led me to leave mathematics and go into political science was thinking I could prevent nuclear war.

I don't know of a single instance of these Arab freedom fighters holding up pictures of bin Laden. I know many instances of them displaying American flags in Benghazi or painting 'Facebook' on their foreheads in Cairo. The idea of freedom . . . is absolutely contradictory to what bin Laden stood for, which was . . . taking Muslims back to some medieval theocracy and encouraging people to die not for freedom but to go to paradise and to kill innocent people along the way. The contrast is really striking.

Jobs are a priority for every country. Doing more to improve regulation and help entrepreneurs is the key to creating jobs - and more growth.

You cant win if youre chasing the wrong problem.

The use of force to liberate people is very different from the use of force to suppress or control them, or even to defeat them.

After a regime is removed, however, it is dangerous to leave a security vacuum.