Wanting to kill people (and/or going through with it) isn't indicative of a mental illness
I AM NOT ADVOCATING VIOLENCE NOR JUSTIFYING IT.
In the wake of the Onion's routine release of their "No Way To Prevent This" article, people like to blame the perpetrator's action on mental illness. That is, some sort of mental instability was the primary cause of a mass shooting. Logically, if that is true, then without that mental instability, the mass shooting wouldn't have happened, the person would have...done something else.
But this is bullshit.
There is a science behind why people commit violence. Why We Snap points out several "triggers":
Life-or Limb
Insult
Family
Environment
Mate
Order in society
Resources
Tribe
Stopped
It's completely reasonable to kill a person in self-defense. Almost no one denies this. That is the primary justification for the proliferation of guns in American society. This is not a mental illness.
At home, 72% of all murder-suicides involve an intimate partner; 94% of the victims of these murder suicides are female. There are a lot of reasons why men hurt and murder women, but fragile male egos that treat women as inferior and interpret their actions as insulting and as challenging to a man's masculinity is an entire trope. And yet, the gender essentialism of traditional masculinity isn't treated as mentally ill (or even just plain wrong).
Similarly, the Nashville Christian academy shooter was trans. For many of us, transgenderism isn't a mental illness, and thus not a cause of excessive violence in and of itself. However, coupled with the antagonistic relationship between traditional Christianity and transgenderism, several of the triggers that don't assume mental illness make sense.
And, of course, tribe...oh boy! As American polarization increases among the electorate, the salience of tribes increases. Only like a week ago, GOP lawmakers that didn't support Jim Jordan's nomination for House Speaker were sent death threats over the phone. If you don't vote for their guy, they'll fuck you up! (But non-violently...listen to the clip). Being protective and supportive of people like you isn't considered a mental illlness.
Again, I don't believe any of this violence is justified, nor am I advocating for it. (I cannot stress that enough). My argument is that there are seemingly rational reasons to engage in violence in the moment. So, rather than scapegoating the mentally ill, maybe, just maybe, we should look to why it seemed like a rational decision for a mass shooter to kill a bunch of people. What was their motivation? What problem were they trying to solve? And why did excessive violence seem like a good way to solve the problem?
I believe this is a much better approach to any shooting or violence in general than the allowing an immediate pivot to mental illness as the causal factor.