A 1 percent increase in gun ownership has been linked to a .5 percent to .9 percent increase in suicides. Photographer: Oliver Bunic/Bloomberg
A 1 percent increase in gun ownership has been linked to a .5 percent to .9 percent increase in suicides. Photographer: Oliver Bunic/Bloomberg

I’m a strong supporter of the Second Amendment. I support the right of everyone except violent felons to have guns in their homes, carry them around in their cars, or wear them on their hips if they’re so inclined. But over the years, I’ve started to think that there are people who probably shouldn’t buy guns. I don’t mean “shouldn’t be allowed to”; I just mean “should exercise their Second Amendment right not to have a gun in their home.”

I’m talking about people with a history of depression. Those folks aren’t a danger to others, yet with a gun in the home, they may be a danger to themselves. “Shall issue” concealed-carry licenses don’t seem to have much impact on gun crime (either to increase or decrease it). But as Alex Tabarrok says, they do seem to increase suicides:

In my latest paper, Firearms and Suicides in US States, (written with the excellent Justin Briggs) we examine the easier question, what is the relationship between firearms and suicide? Using a variety of techniques and data we estimate that a 1% increase in gun ownership leads to a .5 to .9% increase in suicides.

Even if one thinks that suicides don’t cause gun ownership one might imagine that they are correlated due say to a third factor such as social anomie. We have an interesting test of this in the paper. If suicides and gun ownership were being driven by a third factor we would expect gun ownership to be correlated with all suicides not just gun-suicide. What we find, however, is that an increase in gun ownership decrease non-gun suicide. From an economics perspective this makes perfect sense. As gun ownership increases, the cost of gun-suicide falls because guns are easier to access and as the cost of gun-suicide falls there is substitution away from non-gun suicide.

Put differently, when gun ownership decreases other methods of suicide increase. Substitution among methods is not perfect, however, so when gun ownership decreases we see a big decrease in gun-suicide and a substantial but less than fully compensating increase in non-gun suicide so a net decrease the number of suicides.

Our econometric results are consistent with the literature on suicide which finds that suicide is often a rash and impulsive decision -- most people who try but fail to commit suicide do not recommit at a later date -- as a result, small increases in the cost of suicide can dissuade people long enough so that they never do commit suicide.

Someone who is very determined to commit suicide is probably going to find a way. But many people who attempt suicide are possessed by a transient impulse. In one landmark study, the majority of people who were prevented from jumping off the Golden Gate Bridge were either alive years later or had died of natural causes.

If suicide is indeed a temporary impulse, then having an extremely deadly means of self-destruction close at hand is likely to increase the percentage of successful suicides -- and indeed, that’s exactly what Tabarrok and Briggs find. So people who have had major depressive episodes in the past might be well advised to avoid gun ownership or put their guns in the care of a trusted friend. And folks who have recently gone through a horrible life event (job loss, bad breakup or the death of a loved one) would be well advised to get the guns out of the house until they’ve recovered from the blow.

I don’t think this constitutes an argument for stronger gun control; automobiles are a pretty good way to kill yourself if driven into a wall at very high speed, but we do not control access to them because a very small fraction of owners might use them that way. And if you live in a very dangerous area, then I suppose you’ll have to judge the trade-offs. But responsible gun ownership means taking care that your guns are not used to harm innocent people. And if you know that your emotional history puts you at risk of taking your own life, then you should start by protecting yourself.