FWIW, those that are ‘hostile’ don’t generally believe they’re going to convince the people they’re being hostile to. They’re after the peanut gallery; the undecided.
The effect on the peanut gallery is hard to track.
It’s at least as likely that dumping hostility on outsiders is a way of maintaining group cohesion among those who have already identified themselves with the issue.
FWIW, those that are ‘hostile’ don’t generally believe they’re going to convince the people they’re being hostile to. They’re after the peanut gallery; the undecided.
The effect on the peanut gallery is hard to track.
It’s at least as likely that dumping hostility on outsiders is a way of maintaining group cohesion among those who have already identified themselves with the issue.
As you say, in-group signalling is a more likely explanation—hostility is widely unpersuasive to those who are actually undecided.