Don’t get tetchy!
The exact definition, where you draw the line, is obviously a matter for the citizens of each individual country, but there are surely some common sense reasons for disarming certain people. You would not give someone in prison a gun for the very simple reason that he or she would probably use it to get out of prison! You would not allow someone who declared that they were actually “the man in the moon” to have a gun, or indeed any sharp object. I have a friend whose hands shake so much with palsy that they would be physically incapable of aiming a gun. They would be a menace to anyone near them. Then there is the matter of children. Some would say minors should be x years old before they have a gun, some would say y years old.
The point is that there is a proportion of the population in any society who will be forbidden (perhaps temporarily) from owning firearms. Its unrealistic to think 100% of any population will have guns. Actually it unrealistic to think 100% of any population will do anything in common. For goodness sake, not 100% of the population agree the world is round.
1. How many weapons per capita is enough.
2. Whether a person should be restricted from owning a firearm by the government or not.
I believe 1:1 is a good ratio as a minimum and allows for non-functioning arms and users. I would agree to disagree on this.
I don't trust you or the government to make that decision for me. I don't trust me to make that decision for others, unless they are in front of me doing something blatantly stupid. No person should be barred from gun ownership for any reason because that is such a slippery slope that is so easy to abuse. There is some danger from erratic individuals that way, but not nearly the danger that a government taking people's weapons poses.
***there are surely some common sense reasons for disarming certain people. ***
Already taken care of by the Fifth Amendment. Anything else is an infringement.