People talking about guns are using poorer arguments than they ought to be.
Quite frequently, gun control advocates cite studies showing that
increased access to firearms results in more deaths by firearms. On
the other side of the debate, you hear pro-gun folks presenting facts
to the effect that access to guns produces a larger number of "gun
defenses," i.e., attempted crimes that were thwarted by guns.
My problem is this: "Gun deaths" and "gun defenses" are meaningless statistics.
Consider three towns, A, B, and C. Each town has an axe murderer that
kills 3 people a year, and is the town's only source of violent
deaths. Then one year, some event happens that increases each
town's access to guns.
In town A, the axe murderer buys a gun, and becomes a gun murderer. He
commits his usual 3 murders using the gun instead of an axe.
In town B, the axe murderer commits 3 axe murders that year, and 2
more murders also get committed by other people using newly-available guns.
In town C, a vigilante with a newly-acquired gun shoots the town's axe
murderer before he can murder anyone else. That is the only death in
the town that year.
In all three of these towns, "gun deaths" went up. But "total violent
deaths" went down in town C, went up in town B, and stayed
the same in town A.
You can make the same argument about the relationship between "gun
defenses" and "total crimes."
The question people should be asking is: How does access to guns
affect overall safety? "Overall safety" seems like it should be a hard
thing to measure, since it requires you to measure different sorts of
risks on the same scale. How many home invasions are the equivalent
of one homicide? However, this sort of quantification of risk is
exactly the sort of thing that insurance actuaries do for a living. If
owning a gun had a significant effect on the overall safety of your
home, for example, you would expect that some homeowners insurance
would be willing to offer a premium reduction to gun owners, unless of course some market distortion is affecting their calculations. I
recommend gathering your own data on that subject.