If citizens are allowed to arm themselves, an increase in crime rates will cause more citizens to arm themselves, resulting in an increase in the likelihood of criminals getting nailed, which in turn will reduce crime rates.
If citizens are not allowed to arm themselves, an increase in crime rates will cause a larger percentage of crimes to gun unsolved, resulting in reduced deterrence, which in turn will increase crime rates further.
Which seems a better type of feedback system?
Well, that depends on whether your goal is to reduce crime and retain citizen's rights, or to expand police powers and make people more dependent on government, at their own expense. Some people say the former is better, others indicate by their words or actions that they think the latter is better.