I think until you have something rigourously artificial like maths, nothing is truth, nor can be proven to be true. Wasn't that long ago the sun went round the flat earth. The atom was the smallest thing possible or Newtonian physics was the truth.
In politics it's even worse, quite often we are looking at historical numbers that are massively open to interpretation,context and twisting. Have fire related deaths really gone down despite cuts to the fire service, or have we just stopped counting people who subsequently die in hospital, or have I just made that up. Looking forward is even worse as we have economic predictions, made by reputable people who strongly believe their model. But at best, one will turn out to be the truth.
The op is a fascinating question. As a tory though who reads rawk all the time, I found myslef looking at pro tory comments on facebook with a critical lens and espousing myths when they cropped up in conversation. Anti corbyn comments I found myself adding context. To the point I voted labour. Even though the truth is a rare and precious thing I believe its better to seek it out than to stubbornly hold on to beliefs in the face of opposing evidence.
There are well known psychological studies that say we value goods that we own more than ones we don't. And im sure thats true of political beliefs, on that we will refute evidence that opposes our previously stated views. I suppose it's confirmation bias.
