The sinister meme that appeared just hours before the attack on Helen Haines

“Not enough politicians are afraid for their lives right now & I think that’s a problem.”

The comment had been made into a meme, with the words in fancy font printed on an image of a man pointing a gun.

It was posted on the official page of Nichole Overall, a NSW Nationals MP, by an account with a full name and a shadowy profile pic of a man’s back.

“I’ve never had anything of this nature, this was quite shocking. I was taken aback,” says Overall of the post, which appeared on Monday, in the hours before the violent attack on federal Independent MP Helen Haines.

“It’s just not the way, in a civilised society, we should be addressing things,” Overall says, becoming agitated.

Such social media vitriol is a strange amalgam of public and personalised.

It is posted for all to see, but it is deeply silo-ed, which is to say that I don’t know what’s happening in your feed, and you don’t know what’s happening in mine.

You will only see the post on Overall’s Facebook page if it pops up in the online bubble that is perfectly tailored to you, courtesy of a tech company’s algorithm, breeding an isolation that is anything but pro-social.

We live in an age of bombardment, with overwhelming amounts of content coming at us all the time – more content than we could ever need or enjoy.

But at the same time we are increasingly ignorant of the worlds, lives and viewpoints of those who don’t appear in our over-full feeds.

This confusion of content has metastasised threats to public safety, which are now splintered along strange fault lines that don’t necessarily follow traditional ideological positions of left/right.

As Home Affairs Minister Tony Burke said earlier in October of the terrorist threat: “We are getting some weird mixed ideologies, logically inconsistent, all cohering on violence.”

But extremists who deal in hostility do tend to share some common denominators – antisemitism being one, and misogyny being the other.

These two ancient hatreds are useful bellwethers for talk that might turn violent.