So narrative connects information, and information is constructed from a trapezium which, for convenience, is described here as converting an item of data (a difference) into an item of information (which makes a difference in the narrative). The trapezium is part of the narrative, so the process of converting data to information is also dependent upon the narrative. In politics, there is a pretence that, for a given purpose, if you have all the true data there is only one narrative: the true narrative. I say pretence because I doubt that anyone really believes it as baldly as that. However, this is how politicians' arguments line up: we want to achieve this (the purpose); the world is like this (the narrative built on the information) therefore there are no alternative: we need to do this.
If the information is true, the narrative is correct, so the argument proceeds. Post-truth politics doesn't bother with the truth of the information. It presents the narrative and creates the information needed to support it. Those opposed to the narrative cry foul! "You can't just make the information up: it has to be true." Well, there is a problem with requiring information to be true because information is always provisional, but even ignoring that, restricting narratives to those based on 'true' information doesn't get you very far.
The trouble is that there are almost limitless possibilities to choose from for the data, so, even if there is one true narrative to match the chosen data, there are endless narratives that may legitimately be constructed based on which choices are made. Given that situation, how can we chose one narrative over another? How we, as individuals, make the choice, is based on our prior beliefs: our prejudices, our past experiences, the community we share (our 'bubble', to use another current word). Beyond that is the question of what determines which narratives 'win out'. This is about recognising the hegemonic narratives and understanding where their hegemony comes from. The owners of the hegemonic narrative will defend their narrative by pointing to perceived flaws in competing narratives and either denying the data used in competing narratives or ignoring it and insisting on the superiority of the data they have chosen to their narratives. When competing narratives are being judged, much of the time the choice is based on which data you agree to recognise, rather than disputing the truth of the data.
So, looking back to the now-notorious EU leave campaign claim that "We send the EU £350 million a week. Let's find our NHS instead", putting it on the side of bus generated masses of publicity and, evidently, contributed to swaying enough of the voters to win the referendum. Most of the voters were not, realistically, in a position to make an informed assessment of the truth of that claim, or indeed most of the other claims on either side of the campaigns.
As argued in that previous post, the £350 million claim was sort-of true. The problem was that it was (IMHO - which is to say in my narrative!) wildly misleading, because: a) the information that it was converted to by the leave narrative was, questionable and b) choosing different data would support a very different narrative.
The truth or otherwise of the data, while important, is actually quite a small part of winning an argument. (Compare E.H.Carr's statement "To praise a historian for his accuracy is like praising an architect for using well-seasoned timber or properly mixed concrete in his building. It is a necessary condition of his work, but not his essential function".) What matters is the narrative, and the politician's ability to present the narrative.
Mainstream opinion pronounces itself shocked by post-truth politics and takes the moral high-ground, despising both those who present narratives built on falsehoods and those who believe them. But the real problem is the failure of alternative narratives. I referred to 'mainstream opinion' there, and that is part of the problem. Many people are rejecting the narratives of mainstream opinion because they feel let down, and they have been. And of course the concept of 'post-truth politics' is itself information created in a narrative of the mainstream opinion in order to discredit alternative narratives.
This post seems to be leading me towards sympathy for Donald Trump (as the most obvious practitioner of post-truth politics). That is not what was intended, but sometimes narratives take you where they take you. (If you are an academic, anyway. A politician wouldn't let that happen.) And anyway none of this justifies the content of Donald Trump's politics, nor is it a defence of post-truth anything-at-all. What it is arguing is encapsulated very succinctly by something George Monbiot has said:
Those who tell the stories run the world. Politics has failed through a lack of competing narratives.