wpegg: In the spirit of a mature debate, I'd like to make a rambling point that I could easily get to much quicker.
We recently had a press story in the UK where a leadership candidate for a major party, suggested "woman only" carriages on trains in order to reduce the number of sexual assaults on trains (apparently it has escalated recently). He was widely criticised for this suggestion, the main reason being that women shouldn't feel they need to be segregated. They should be free to travel in the same carriage as men without fear of assault, and to simply remove the women from the location is not addressing the actual problem, which is that there are men sexually assaulting women on trains.
When I hear people making the "defense" argument for gun control I think of it in a similar way to the train carriages. You shouldn't address the problem of psychopaths armed with guns being able to wander around freely by making sure everyone is also carrying guns so it's a level playing field, you should address the problem by stopping there being psychopaths with guns. That' could be through better vetting of who can own the guns, or reduction in the availability of guns. However when people say they need them to defend against these people, I feel they're disguising the issue.
Personally I wouldn't want to live in a country where I would feel that it was sufficiently possible (such that I'd by a gun) that I would need to shoot someone in the course of my everyday life. That is (in my opinion) not a solution.
It's not about constantly worrying you're under attack - it's about having a right to be able to defend yourself. The difference is subtle but important. Most US citizens have never seen a gun or felt the urge to have one, just like in many other 1st World nations.
TL;DR of below: Better enforcement of existing laws is necessary. Better education / licensing requirements would be a perfectly reasonable addition to that. The problem isn't guns, it's people who shouldn't get a license but can due to bad IT setups / FBI not talking to sellers / sellers not talking to the FBI.
In the US we actually are supposed to have background checks and other things to keep potentially dangerous people from getting guns. But often when someone goes crazy with a guy, it turns out the actual checking process is so bad that people who shouldn't have guns get them. We don't need more laws or high-tech triggers or whatever. We do need to enforce the actual legal limits on gun ownership. If there was a more straightforward licensing scheme a la driver's licenses that would be a good idea too.
Most people who use guns are responsible, intelligent people, but of course they don't make the news. There's nothing camera-worthy about a person who has a job, a family and goes hunting some weekends.
Re: Psychopaths with guns, the problem is more cultural acceptance of mental health treatment and violence. Also, demographics.
Laws can't really do much to make people more willing to be open about possible craziness, and every attempt to limit the cultural acceptance of violence has met really extreme reactions - just check out how people reacted to Target not selling GTA in Australia.
If people see violence treated as an acceptable solution to interpersonal situations in entertainment than the ones who have trouble dealing with reality are going to be more likely to use it IRL. How many people do you know who refuse to listen to what they don't want to hear, treat every bad thing as a personal insult or are otherwise mildly delusional? More than you want to realize, probably. Due to the really crazy way that debate got started no one wants to talk sensibly about how media culture impacts viewers, which I think is a major disservice.
Demographically, the US is so much larger and more diverse than any single EU country that comparisons are really problematic. Specific example of how demographic differences impact this question:
Lots of gun control proponents talk about how the UK has ditched guns for example, but that's really only possible in a very small and relatively homogenous place like the UK - and yes, the UK is ethnically and culturally homogenous compared to the US, and also more tightly packed. There's simply fewer people who are potentially criminals, fewer gaps between cultural expectations that can cause miscommunication, fewer places to take off to once something happens, smaller black market, etc. The US is also at the crossroads of major international shipping and so there's a large problem with drug cartels that I don't think people understand until they've lived with it. Police in certain parts of the country really couldn't effectively police without guns, and in other parts they genuinely don't need them. Criminals have guns regardless of gun control laws, but ordinary citizens have trouble arranging to defend themselves when they really need it - Washington DC is a good example of this, with a gun control law so strict it was unconstitutional causing massive harm to the citizens because criminals preyed on them at will.
It's a complicated question that gun control advocates often reduce to 'Don't let people have guns because guns kill people and getting rid of guns worked in the UK'.