Potential mass shooters aren’t easy to spot, but the contradictions in our logic about them are:

The kinds of severe mental illnesses we’re so often afraid of don’t seem to be strongly associated with mass violence.

The serious mental illnesses that are loosely linked with violence are still a poor predictor of who will become violent.

The mental illnesses that seem to be common among people who commit mass violence aren’t good predictors of violence.

And we have no idea how people who commit mass violence differ from the general population — we only know what they have in common with each other.

You can see the problem. This is why experts say we shouldn’t be talking about mental illness as a cause of mass violence.