John Mearsheimer

And before I tell you what I think the differences are between those two bodies of theory, it is important to emphasize that there are differences among realists and differences among liberals.

And so when you talk about me as an offensive realist, you should understand that there are also defensive realists out there, and there are a panoply of liberal theories as well.

But basically, realists believe that power matters, that states compete for power, and that war is an instrument of statecraft.

And liberals, on the other hand, have what I would say is a more idealistic view of the world.

This is not to say that they're naive or foolish,

But they believe there are aspects of international politics that lead to a less competitive and more peaceful world than most realists see.

And I'll lay out for you very quickly what are the three major liberal theories today that I think will give you a sense of the more optimistic perspective that is inherent in the liberal enterprise.

The first and most important of the liberal theories is democratic peace theory.

And this is a theory that says democracies do not fight against other democracies.

So the more the world is populated with democracies, the less likely it is that we will have wars.

And this basic argument is inherent in Francis Fukuyama's The End of History.

He argues that democracy triumphed first over fascism in the 20th century.

It then triumphed over communism.

And that means that in the future, we're going to have more and more liberalization.

liberal democracies on the planet.

And if you have more and more liberal democracies and those democracies don't fight each other, then you have a more peaceful world.

That was his argument.

It's a very liberal argument.

A realist like me would say that it doesn't matter whether a state is a democracy or not

All states behave the same way because the structure of the system, getting back to our earlier discussion about international anarchy, the structure of the system leaves those states no choice, whether they're democracies or autocracies.