How does the pro-gun lobby reconcile itself with American exceptionalism?

Following the awful, awful news of the massacre in Conneticut, the gun-control debate has begun afresh in the USA.
The canard from those who support the current, ridiculous status quo, is that the problem lies in “evil people doing evil acts”, and not the availability of weapons.  How do the pro-gun advocates reconcile this argument with the doctrine of American exceptionalism?
If one holds that permissive gun laws have no causal connection to the frequent massacres, and that the daily murders are simply caused by evil of people… then one is left with the heretical conclusion that there are simply more evil people in America than elsewhere.  This does not sit well with the idea of America being intrisically better than other countries.
Shibboleths collide! Call for Doctor Pangloss!