In my earlier post on “The gun violence lottery” I presented the math behind my contention that the rise of American gun violence is mostly correlated simply with the accelerating rise in the availability of guns in America. The short version of the proof is found in the “should be obvious” fact that other “first world” countries have all of the other “causes” expounded upon at length by the punditry, but far less gun violence. Folks, it’s the guns.
“The gunman is mentally ill” is one of the more egregious “causes” expounded, and in this post I will tell you why any pundit exploiting this point is simply wrong.
First of all, this label, as applied to most of the recent mass violence shooters, is simply self-definitional and non-predictive. Get the self-definitional logic here: “The shooter must be mentally ill because only mentally ill people shoot other people.”
There are millions of Americans (and hundreds of millions world-wide) who qualify under some broad range of professional diagnosis as “mentally ill.” The definition above does not qualify. There is no evidence that mentally ill people kill people in any larger percentages than is the case for those of us currently not tagged with that “mentally ill” label. There is some correlation with higher rates of self-harm, but that itself a gun-related problem. Only in the U.S. are gun-based suicides so obscenely high, with over 20,000 per year. 
Let’s think a minute people, about the shooter in the most recent Parkland, Florida event. The shooter was captured and will either go on trial or plead. There already are calls for capital punishment here, but we don’t (officially at least) execute people who are mentally ill, even in Florida. So, is he mentally ill or not? How do you resolve the conundrum?
This shooter made a threatening post online, and there is criticism of the FBI for ignoring the post. There is an investigation gap to probe here, but would this qualify him as “mentally ill” and subject to involuntary commitment under current diagnostic guidelines? Was not the information that the school knew in expelling him more directly relevant and worthy of tracking? The unspoken story here is that, either in online comments or school expulsions, this record of disturbing comments, combined with gun access, is not as uncommon as is being portrayed.
Those who think this behavior is rare have not been exposed to the pervasive hate-spewing culture that dominates much of the Internet, with Youtube.com comment sections, where this shooter’s comment was made, among the worst. In short, this shooter has lots of company online. Which ones would you have the FBI act upon? Which ones would you track in a database? Which ones would you commit as “mentally ill”?
And if someone does act upon anecdotal threats of violence or odd observed behavior, please tell me exactly how this information will (1) get into some official interstate database, and (2) actually be used to prevent the sale of a firearm. The reality is that we are going in exactly the opposite direction here. One of the first Trump presidential acts was to reverse an Obama directive that would have put the names of people adjudicated of being unable to manage their own affairs due to mental illness into a national registry. And the recently-released Trump budget drastically cuts the funding for maintaining gun registry databases. The ATF is currently not even allowed to digitize gun records in order to trace weapons used in crimes, necessitating slow manual searches of thousands of boxes of records daily. 
And not coincidentally, the culture most expressing hate on the Internet is also a culture that loves collecting guns, especially the most “efficient” ones like the AR-15, and loves boasting about it online. The scandal here is not about how this one shooter was undetected or “mentally ill”, but rather about how you likely have some very scary men in your community right now who are not that much different from this shooter. What will be the trigger that sets these men off? It’s more probability and inevitability than “mental illness.”
And I do mean men. Some breaking scientific news here: 50% of humans are born with a genetic condition called an “XX” chromosome, and virtually NONE of them commit mass gun violence. We call these “XX” holders women. So already, we can dismiss 50% of “mental illness” diagnoses as having anything to do with gun violence. That was easy! Now, how do we deal with those aberrant holders of “XY” chromosomes who have the urge to shoot stuff?
Folks, it’s the damn guns.