ISIS, terror, mobs and what makes a state a state

When the Carney brothers got together over Labor Day weekend, one of our activities was seeing how many countries each of us could name. (You’re jealous, I know.) At one point, this became a debate over whether Niue counts as a country. This, of course, led to a discussion of what makes a country a country. Along the way, the question arose: is ISIS really a state?

You can consider the Islamic State of Iraq and Syria a terrorist organization, but you can also consider it a particularly murderous and oppressive state. Which is it?