The problem is: democracies can’t function properly if there isn’t a shared truth, no matter how broad, among the voting public.

And yes, the split in our shared reality didn’t happen overnight. It has eroded for years with the help a strident, polarising Murdoch media and talkback radio, much of which is spread widely online.

But social media’s ability to filter the facts, and experience, has accelerated this trend to a crisis level.

This is something being learned the hard way in the US, when life and death decisions are being taken on worldviews that are only half-shared within the nation.

Australia’s bushfires show why democracy requires shared truths