guns and causation

[mindstalk]

I'm reading Judea Pearl's _The Book of Why_ (Caltech book club), about causal inference and types of causation. Just got through necessary vs. sufficient causation. It seems to me that captures part of the gun debate: widespread gun ownership is necessary for frequent mass shootings (no guns, no shootings) but not sufficient (we can imagine lots of guns without shootings... like most of the US's own history).

Gun control advocates point out that taking the guns away will stop the shootings; gun rights advocates argue guns aren't really to blame.

Pearl's own illustrative example is a house fire: a match (or some other ignition) is both necessary and sufficient, oxygen in the air is necessary (no oxygen no fire) but not sufficient (just adding oxygen doesn't start a fire). That includes an assumption that oxygen is 'normal', present whether or not the match is (thus enabling the match to be sufficient, because we can assume the oxygen is there).

Are guns like oxygen? For a lot of the US, yes, in being ubiquitous, considered normal, and mostly not killing people. Removing oxygen to prevent fires is usually overkill, and they would say removing guns is too.

Other modern crises:

* greenhouse gases are reasonably necessary and sufficient for global warming. (No gases, no warming; adding greenhouses gases to an 1800 AD background suffices to cause warming.) (As a side note, Pearl points out that climate models allow climate scientists to generate counterfactual 'data' quite easily, by tweaking model parameters.)

* cars and deaths: cars are necessary for 40,000 dead Americans a year (no cars, no such deaths... alternative transport modes aren't nearly so dangerous) and sufficient (adding cars, or rather a car-oriented and -dependent culture[1] is the main reason we have the deaths).

[1] Japan actually has 3/4 as many cars per capita as the US, but 1/3 as many road fatalities per capita; the cars are used less, as well as being smaller and slower in common use. Many fewer deaths per vehicle too, but similar deaths per vehicle-km.

Comments

[heron61]

Are guns like oxygen? For a lot of the US, yes, in being ubiquitous, considered normal, and mostly not killing people. Removing oxygen to prevent fires is usually overkill, and they would say removing guns is too.

Except that not only are murder rates far lower in nations with strict gun control, but from Australia's example, we know of an absolute fact that strict gun control drastically reduces the numbers of mass shootings. Of course, there's also the fact that removing oxygen tends to have negative consequences, and other than annoying people, removing guns simply does not

From the stats we have, they are largely useless as personal protection, and other than hunting weapons (I have no objection to the sale of pump action shotguns and bolt action rifles), absolutely nothing else is lost on any sort of practical level, and hurt feelings seem vastly less important than dead people.

[mindstalk]

Your first sentence is consistent with guns being necessary for shootings; it says nothing about whether they're sufficient. The existence of other countries with high gun ownership and whether they have high shooting rates would be more apropos. A recent article said "yes" but a friend noted that the graph included was not very convincing. Part of the problem is that there aren't any countries with similar levels of gun ownership, so there are few international data points. Also the independent variable is usually "guns per capita", when "capita who own any guns" might be more relevant.