George Herbert once wrote, “One sword keeps another in the sheath.” Later Robert Heinlein expressed a similar idea in Beyond This Horizon when he wrote, “An armed society is a polite society.” Today many people would argue the idea shared by Herbert and Heinlein is destructive. They argue that peace can only exist when the general population is unarmed but acknowledge the need for weapons to enforce such a prohibition so generally approve of the military and police keeping their weapons. But Herbert and Heinlein were correct, peace tends to prevail when no disparity of force exists.
Force is an appealing option when one enjoys a greater capacity for it than their target. We see this every day with violent criminals. Amongst violent criminals there is a great tendency for targeting easier prey. The criteria that determine how easy a target is varies. If the criminal is physically strong they may see physically weak individuals as easy prey. If the criminal has a gun they may see anybody who is unarmed as easy prey. If the criminal is with friends they may see any group they that is numerically inferior as easy prey. Most criminals see people who are entirely unaware of their surroundings as easy prey. In general criminals target those they believe to have a lesser capacity for force than themselves. Economically this makes sense because the risks of employing violence decrease when your force advantage over your target increases.
But force becomes unattractive when your target enjoys an equal capacity. The reason for this is obvious. Force carries with it the possibility of severe injury or death. That’s what makes force appealing to those who enjoy a sizable advantage. But it also means a target that is on equal footing with you stands a good chance of injuring or killing you. If two renowned swordsmen are both carrying their swords the likelihood of a disagreement between them turning violent is going to remain fairly low. Both of them know drawing their sword will cause an equal reaction from the other and the outcome of the fight may very well include the loss of limbs or life.
This principle remains even on larger scales. A nation only tends to declare war against another if it believes it’s in an advantaged position. When a nation doesn’t believe it enjoys a force advantage it tends to use diplomacy. The United States and the Soviet Union avoided a direct war because both had enough nuclear weaponry to wipe the other out. Napoleon invaded Russia because he believed his military was superior and that would ensure his victory.
One of the reasons I believe stateless societies tend to be more peaceful than ones under statism is because the disparity of force between the people and the State is nonexistent. Iceland’s stateless period, medieval Ireland, the Old American West, and Neutral Moresnet are all examples of stateless societies that tended to be very peaceful when compared to their statist neighbors. Since there was no organization with a great force advantage over everybody else the tendency was for people to choose diplomacy over violence.
The desire to eliminate disparity of force, and therefore reduce the appeal of using violence, is one of the primary reasons libertarians tend to be supporters of allowing individuals to be armed. They recognize that one gun keeps another in the holster. It is also why even libertarian statists tend to support individuals enjoying arms parity with the police and military.