There is certainly a lot of research about the radicalization process, generally aimed (unsurprisingly) at terrorism rather than isolated murderers. I don’t have a signal succinct citation to point you to, but I am relatively confident that there is good evidence to support the claim that an individual being increasingly surrounded by media espousing a radical or fringe belief is correlated with that individual becoming increasingly radical.
That doesn’t answer your question about justifying censorship, but I think that’s not the best question to ask, since media recommendation algorithms that penalize certain radical subjects is hardly what I would call “censorship.”
>I am relatively confident that there is good evidence to support the claim that an individual being increasingly surrounded by media espousing a radical or fringe belief is correlated with that individual becoming increasingly radical.
I get where you're coming from but I have some issues with that perspective. Would you agree that a conspiracy theorist who uses physical violence and/or threats of physical violence is strong indicator of a dangerously radicalized person? Then how can we explain the large number of people exposed to radical media but only a small handful performing radical violence? Are conspiracies and radical beliefs always some kind of treadmill where you take a nibble and then inevitably go deeper and deeper until you become so delusional that you feel the need to take violent action? To me that feels too much like a just-so narrative.
Also, I think we should be concerned about what some people consider "radicalization." Everyone is against radical violence and media that contributes to that end. But what about media that makes someone a Trump voter? Rhetorically some argue that they are just as dangerous as any shooter because they create a social environment that precipitates violence, even though the causation isn't direct.
It's difficult to talk about these things without coming up with false dichotomies or bad generalizations. Really what I'm trying to get at is a "throwing the baby out with the bathwater" understanding. It's easy to get rid of the baby when it's not your baby or the baby is casually stereotyped in an appealing way.
> Then how can we explain the large number of people exposed to radical media but only a small handful performing radical violence?
Surely there's some various in the predisposition of individuals to become radicalized, but I don't suspect that means that people who do become radicalized would inevitably have become radicalized regardless of their exposure to certain ideas. The fact that terrorist groups put a lot of effort into radicalizing people indicates that they are under the impression that their efforts are meaningful. Even if the predisposition for an individual to become radicalized is already determined and unchangeable, there is an incentive for various radical groups to radicalize those people under their banner rather than some other banner.
> Everyone is against radical violence and media that contributes to that end. But what about media that makes someone a Trump voter? Rhetorically some argue that they are just as dangerous as any shooter because they create a social environment that precipitates violence, even though the causation isn't direct.
I agree that there's a continuum here, and that it's extremely subjective. I think most people agree that explicitly inciting violence is not (and should not be) protected speech/communication. But what about communication about groups dedicated to violence that don't explicitly mention violence? Then what about groups espousing philosophies which are strongly correlated with advocating violence, like blatant racism? Then what about groups that espouse philosophies described to just barely not quite be blatant racism, like "white nationalists" who explicitly advocate for "peaceful ethnic cleansing" of certain people from certain regions, but claim to not be racist and not support violence? Do we throw up our hands and say "well, they said the word 'peaceful,' therefore they're not technically advocating violence, therefore it's protected speech"?
That doesn’t answer your question about justifying censorship, but I think that’s not the best question to ask, since media recommendation algorithms that penalize certain radical subjects is hardly what I would call “censorship.”