An ideology can be renounced and turned away from, even if it has become habitual. It can be combatted. The young can be educated against a dangerous ideology. But we throw up our hands at "mental disturbances;" they seem unpredictable and very hard to correct.
The news media seemed all set to present Isla Vista as an all ready familiar narrative. Mentally ill person plus easy access to guns equals mass murder. Cue the Gun control debate.
That narrative was disrupted. The fact that the shooter left a misogynist manifesto could not be ignored. And when it was reported, women started reporting the effects of misogyny and rape culture in their social media streams. They named the problem. And they started to identify the sources of cultural messages that promote rape culture in popular culture. They called out men's complicity in it.
This is how social and cultural struggle happens now. It is not the civil debate between columnists of the New York Times op-ed page. It is not erudite or abstract. #YesAllWomen prevailed because it brought forward a tidal wave of individual testimonies which established the real truth, on the ground; how it really happens.
Ordinary people know the full truth about the realities of living in this society. They know what it like to live on the minimum wage. They know what it feels like to have no health insurance. They know how a steady stream of microaggressions wear people of color down. They know how hopeless long term unemployment is. They know that there are no jobs, or no buses to the retail jobs that do exist. They know the fear of living without papers. They know the social vulnerability of gender nonconformity. They know it all. The truth is out there.
And when the truth get told in massive numbers, as it now can, it changes the way that the world is seen and known.