So does Israel, I saw a report that claimed that 30% of terrorists were killed by civilians before committing the act (pulling cord to set off suit of bombs).
I distrust most big cities as the police will stay out of areas at night. If I know that most people are armed then I feel safer. I would help others and they would help me if I needed it. Things get politer and safer. Bad people will have weapons one step over the good guys. why not make them have to take more chances to win at crime. It will also keep the jails empty of repetitive crooks (they will be dead, too bad
)