I've been reading more of Makers of Modern Strategy, and found myself introduced to ideas of nuclear force as a cost-effective army, and that a balance of destructive forces can produce a stability that overwhelming superiority never could. It's an outdated thing to talk about, but the balance of power is pretty impressive. I mean, it worked. Of all the ideas out there for nuclear conflict, being scared shitless worked best.
And here is the other funny part - excepting the paranoia, large nuclear forces are cheaper to maintain than a comparable conventional force. Also, with the prevention of wars, they are perhaps more effective. I mentioned this to the girl, and she replied that it was still all a waste. Which is a valid point, to a degree. If something isn't going to be used, resources spent on it are a waste. And then, resources spent on world-ending weapons are just never a good idea.
The first potential counter is that even when not fired, nuclear weapons have a point, and that the cost spent on them as a deterrent is much better than the costs of weapons actually fired. So, nuclear weapons were being used, just not launched. So the resources spent on the weapons were not (entirely?) wasted. This certainly doesn't answer the question of the need for force, though.
Force arguments are often weak. The classic is "if we don't, they will", and that's pathetic and circular. If we are afraid of a use of force against us, we should maintain a comparable force to make the risk greater than the benefit of an attack. Without fear of attack, and stable nation has no need for an armed forces. I had originally written more on this, but the core idea is now apparent. Military force is necessary for those who have something to lose. Since government is the surrendering of some rights for the guarantee of something (generally property) people with a government have something to lose.
Military force provides a way to secure what a people, as a collective, hold. Military force also provides a way for people, as a collective, to attempt get what they lack. And these forces can maintain an equilibrium of opposition, but since conflict has a lot of variables, nothing is never nailed down or guaranteed. Nuclear forces, while risking the existence of the world, also prevent conflict, and are an oddly stabilizing force.