Although Kahn's ideas had some merit, and many were adopted in some form, there are good reasons why MAD remained the fundamental US (and Soviet) strategies for the rest of the Cold War. First, it was cheaper, and it was easier to predict how it would work under the severe stresses of a shooting war. Second, it produced a dynamic where nations endeavored to steer away from the brink, no one could predict where the slippery slope of ratcheted escalation would lead to in the days of tension preceding a nuclear exchange. Third, everyone doubted if Kahn's finely managed response and flexible war-fighting concepts could be carried out in an environment where whole levels of command and control and communications links would be wiped out and open to enemy spoofing and interception. But most of all, Kahn failed to fully explore the possibilities of what might happen if things didn't work out the way he had anticipated they would.

This is best communicated by consideration of the issue of Civil Defense. One of the so-called defensive strategies proposed was the big civil defense evacuation in times of international tension. It was felt that the capability to evacuate the populations of our urban centers to prepared camps in the country could greatly reduce the number of casualties both during the attack and post-attack phases. But what would actually happen in such a scenario?

Let's say a period of international tension escalates after trouble breaks out in some remote hot-spot. Both sides start rattling sabers and the tension builds, the two sides are mobilizing and negotiations start to break down. If one side suddenly begins the evacuation (which might take weeks) in order to prove it "means business", the other side will be forced to follow suit. Pretty soon the two nations are toe-to-toe with their people living in tents tens or hundreds of miles from their homes, perhaps in winter. The cities are abandoned and falling apart due to neglect and vandalism, food stocks in the camps start to run out, it becomes harder and harder to control and service the evacuees, disease breaks out, civil strife, troops have to be called in to maintain order, no one can communicate with distant family memebers, and industry and commerce grind to a halt.

Clearly, both sides are under great pressure to return to the cities, but the minute one does, it gives the other the perfect excuse to launch a first strike, perhaps one not even aimed at the cities but solely at military installations. The victim cannot effectively retaliate because his opponents will have most of their people dispersed, along with the essential supplies needed to rebuild that society, and his people will be streaming back into their towns to take the brunt of any third srike. Not only that, the authoritarian nature of Soviet society made it possible to carry out this sort of policy much more effectively than US democracy could, they evacuated whole cities and industries in WWII to hastily built industrial centers east of the Urals.

The ideas of "survivable nuclear war", "managed nuclear war fighting", "flexible response" as conceived of by Kahn were simply too risky to try. Might they have worked? Perhaps. Could MAD have failed? Its possible it might have. But those are alternative realities; as it turns out, history testifies that we made the right decision.