The Democratic peace theory is a theory in political science which says that no two Democracies have ever gone to war, or will ever go to war. Governments answerable to the people will never go to war with each other, and tend to find alternatives (such as negotiation or arbitration)

The Correlates of War Project has done studies to evaluate the historic merit of this theory. In some 2,000 cases of war or other armed conflicts, they could not find a single case where the theory did not hold.

It should be noted that statistically, this is an association, and association does not imply causation. There is currently no definitive theory as to why the democratic peace theory is true.