By Zachary Keck
One of the most enduring concepts (PDF) in international relations theory—particularly the Realist variant of it— is the offense-defense balance. The offense-defense balance is basically, in two scholars’ estimation, “the ratio of the cost of the forces the attacker requires to take territory to the cost of the forces the defender has deployed.”
Proponents of the offense-defense balance argue that when military technology and doctrine favor the offense, the security dilemma is more acute and war is more likely. For example, proponents of this theory hold that one reason that WWI broke out was because all the parties believed that the opening salvos of the war would be decisive in determining its outcome, and therefore felt they had to act first since so much advantage was gained from doing so.
Of course, the military technology and doctrine at the time of WWI did not in any way favor the offense; quite the contrary. Thus, one of the most stinging critiques of offensive-defensive balance theory is that it is impossible to distinguish between weapons and doctrine that are purely offensive versus those that are purely defensive in nature. As Michael Brown has summarized these critics’ argument, "Whether a weapon is offensive or defensive depends on the situation in which it is used."
Read the full 2 page story at The Diplomat