I wrote the following in response to a massively down-voted AskReddit post and figured I may as well repost here:
Liberals, writ large, don't all want to ban guns but they do want differing degrees of restriction upon them so I see where you're coming from with the "ban" language; a ban in whole or in part is still a ban. Likewise, while such a "ban" likely won't "stop" violence completely it may significantly reduce it which is another "in whole or in part" type thing. These linguistic quibbles matter because, as we are about to see, this issue isn't as terribly simple as many would like it to be.
So why do I think stricter gun control will reduce violence?
First, what is a gun? Firearms are mechanical and chemical devices which have existed for centuries. Black-powder or smokeless, muzzleloader or full-auto, they use propellent or explosives (non-replica black powder is an explosive) to move a projectile down range at high velocity with the intent of damaging or destroying the target. This is what a gun-as-a-tool does and, as a tool, it has evolved to be better and better at its primary application: killing things.
Because, make no mistake, that's what guns are for. A saw is a tool for cutting through wood and a gun is a tool for killing things -- most notably people, though it does a damn fine job on various animals too. Sure, you can use a gun for other things and you can play a saw with a violin bow, but only a very great fool would contend that a saw is primarily a musical instrument or that a gun is mostly for signaling the start of a race or something.
Like most tools, a gun makes its user more efficient, effective, and expedient at whatever the tool is designed to do, again, in this case, killing people. Almost every innovation in firearms manufacturer over the last several hundred years has been spurred on by this impetus. Better locks make for more reliable discharge. Better powder for less fowling. Better rifling (or rifling at all) for better effective range. Better actions for higher rates of fire. All of these and more were brought about by combat conditions - situations where men sought to kill one another and any edge meant the difference between life and death.
All of which means that guns, placed in the hands of men, make those men more efficient and more lethal killers. Guns don't kill people, as the NRA reminds us, people kill people. Guns just make people much better at killing people.
I needn't convince you of this rhetorically; the evidence is all around you. Guns don't make people suicidal but suicidal people with guns in their house are far more likely to successfully take their own lives. Guns don't make kids shoot one another, but kids in houses with firearms are far more likely to be shot.
Categorically, a country1 without easy access to guns is a country with far fewer firearms related deaths. Violence still exists in countries with and without firearms bans but the severity of that violence is mitigated substantially if firearms are restricted and the government is able to enforce that restriction.
A strong parallel may be found in the United States with the regulation of either automatic weapons or explosives. In both cases, tools which are even more effective at killing people than the run-of-the-mill firearm are tightly regulated. As a result, while we do still see violent crimes committed with these tools, they are far less prevalent in our crime statistics. Yes, there are occasional shootings with full-auto weapons and there are occasionally bombings but these are much less common than shootings with more mundane firearms.
Why? Certainly the NRA's other favorite adage applies in both cases. "If you criminalize ______ only criminals will use ______." Yes, there are legal ways to own and operate both full-auto firearms and even explosives, but tight regulation makes them scarce on the black market. Criminals, either unable to stomach the price or unwilling to endure the hassle of trying to find these more exotic weapons seek more pedestrian ways to achieve their ends.
And in a real sense, that is what it comes down to. Yes, if you eliminate all firearms people will still beat each other with bats and cut each other with knives. Some will get a hold of the odd gun, make their own, smuggle them in on boats from South America or whathaveyou. But in each of those cases the cost of using a firearm to commit a crime in both money and time goes up while the benefit goes down. If you can as easily intimidate someone with a knife why do you, as a criminal, need a gun?
But despite this bats, knives, etc remain far more survivable. Violence may not stop with the regulation of firearms but the survival rate of violent crimes will rise significantly. We will see fewer people killed in schools and shopping malls, fewer domestic disputes that end in the morgue, fewer suicides that succeed, and fewer lives ruined by an unexpected discharge.
"What about self defence," you ask. "What about personal safety? Wouldn't you want your daughter to have a gun if someone tried to rape her? Wouldn't you want your wife to have one if someone barged into your home in the middle of the night?"
Of course I would. In those situations I would obviously like them to have a gun but having a gun in those extraordinarily rare situations means having one in the far more likely event that nothing of the sort happens. What about the risk of suicide? Of accidental discharge? Of your kid-sister's friend finding your gun and playing with it? Would you want your wife to accidentally shoot your son when he comes home from a party late? Wouldn't you rather NOT have a gun in your house in that situation? The "what if" game cuts both ways, but one set of circumstances occupies the space of the every-day and the odds of something going wrong pile up over the years. The simple truth is that your family is safer without a gun in the household than with one.
So why do I think banning guns will stop violence, or at least think that regulating them will reduce it? Because guns are tools which make people better at killing; a population less skilled at killing kills fewer people. Because economics drives the actions of criminals and law-abiding citizens alike: it's harder and more expensive to acquire guns in countries that strictly regulate them. Because statistics show that owning a gun is a risk in and of itself; a firearm is far more likely to play a role in the death or wounding of it's owners' family than it is to protect that family.
It's a numbers game. Regulation saves lives.
1. Not a city or state. This often gets confused in the gun control debate. The lack of meaningful customs borders between cities and states means that non-federal firearms control legislation is ineffective and disadvantages law-abiding citizens who will not, as a rule, smuggle guns across state or municipal boundaries.