Men live in a world that women will never understand. It's a world of measured respect for other men necessitated by the mutual realization that we have the ability and the testosterone induced motivation to kill each other. Even the winner of an all-out man-on-man confrontation is going to walk away with serious – often debilitating – scars. This knowledge is the only thing that keeps men – naturally individualistic, opportunistic, and aggressive animals – from each other's throats when they are in close proximity.
The threat of mutually assured destruction, acronymised as MAD in the 1960s, wasn't invented by Robert Strange McNamara. It was invented 10,000 years ago by mankind as a tenuous glue to hold a society together. When the invention of agriculture induced men to live together for the mutual advantages of shared labor and shared defense, they needed something to temper their natural inclination to murder their neighbor and steal his wealth and his women.
That disincentive was provided by the knowledge that your neighbor harbored the same lust for your wealth and women, and that you must, therefore, concentrate on protecting what you had rather than on stealing what he had. Thus civilization, for men, has been a 10,000 year standoff.
If you doubt the validity of this assertion, witness what happens when the perception of the threat of mutual destruction is removed, as in incidents of road rage or the penning of anonymous verbal attacks on the internet or in the press. You will do or say things to another man when insulated by the anonymity of physical or electronic separation that you would not dare do or say to his face for fear of immediate and damaging retaliation.
Mutually assured destruction has always been emphasized by the mechanical leveraging of muscular force. From the Neanderthal's club through the Greco-Roman/Medieval/Renaisance sword to the Industrial revolution's firearm, man has always sought to augment the threat of mutual destruction with weapons. The Marine Corps mantra is an iteration of the civilized male mantra : "Never surrender your weapon."
Thus weapons have become an integral and necessary component of civilized man – and hence of civilization itself. Whenever the possession of weapons has been curtailed, as in Germany in 1938, the result has been a precipitous decent into barbarism and chaos. If every German in 1940 had been armed with a Mauser and 200 rounds of ammunition, the Nazi Party would be a minor footnote in the history of the Weimar Republic.
It is not the destruction of your enemy that assures peace and tranquility in a society – it is the credible threat of destruction. You don't have to walk into a barroom and knock the crap out of every man there. You have only to rely on their knowledge that you are capable and willing, if called upon, to kill any one of them.
But in order for this civilizing influence to work, whether among men in a barroom or between citizens and their government, the means of force must be mutually possessed.