Do guns cause violence? Numbers guy Robert VerBruggen writes for
RealClearPolicy real
wisdom about this issue.
The two fundamental laws of gun studies are: One, if a given author reaches a pro- or anti-gun result in one study, all his future results will point in the same direction; two, if it appears in a public-health journal, the results will suggest guns are bad.
A more clear-cut evidence of bias would be hard to find. So what do studies show, in his opinion?
What we have learned is this: A bunch of states started letting almost any random person walk around a gun, and if anything good or bad resulted, it doesn't reliably show up in the data.
VerBruggen concludes:
Yes, it's possible that confining gun ownership to the people willing to jump through various government hoops might have some marginal effect on violence. But that effect will probably be so small as to be difficult to detect, and there may be no effect at all.
On the other hand, confining insane people in mental hospitals (or prisons) will have a positive effect, directing most of their violence at fellow inmates.