Obi_Kwiet
It's Stuart, Martha Stuart
Posts: 7,943
Well, the 2and amendment reads like this: "A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
The first part provides context, but the actual right is, "the right of the people to keep and bear Arms, shall not be infringed.". So it seems like the author believed that people should be able to keep and bear arms, at least in large part because private ownership of arms is pretty important if you want to set up a militia. For example, if a nation invaded, it's going to be very difficult to make progress if they has access to a large decentralized stock of weapons. You can pull up a fighting force of some kind from anywhere there is a population center without having to source firearms and ammo. That's a pretty huge deal, especially back then.
Now, that particular justification is somewhat obsolete, but the right is simply to keep and bear arms, and people today value it for reasons beyond the one originally given. I suspect that that may have always been the case. Imagine if the first amendment had read, "A honest and diligent press, being necessary to the accountability of the government, the right to free speech, shall not be infringed." You would obviously be able to tell that the author felt that freedom of the press was a key motivation for freedom of speech, but that doesn't mean that it was the only motivation for it, nor that it should be restricted in all other circumstances. I'd interpret the law as, "You have a right to this thing, but it's especially important that it be interpreted to facilitate this particular application."
Going back to the first example, the militia prevents an interpretation that allows weapons suitable only for self defense. For example, a prohibition on all guns except hand guns.
The second amendment has never been interpreted as a total prohibition on any kind of weapons legislation, but I think machine guns are pretty reasonable for people to own, given that they aren't particularly dangerous relatively speaking, and have a military application. The Heller decision upholding handgun ownership isn't totally out of line, but it is more of a stretch, because the amendment doesn't specifically hold up personal defense as a primary motivation.
You can complain that the idea of a militia is out of date, but there is a legal process to correct that. It's called passing a constitutional amendment. It's a terrible idea to end run around that by simply hand waving away laws that we don't like. Constitutional amendments are hard to pass on purpose. The idea is that the entire country needs to be in strong agreement that this is the right way to go. If you don't have that level agreement, than you we shouldn't be changing aspects of the law that are that fundamental.