It’s no lie. The Oxford Dictionary’s international word for 2016 is “post-truth”. This new, fancy word tells us: “Objective facts are less influential in shaping public opinion than appeals to emotion and personal belief.” No need for truth, it is yesteryear’s notion.
There is nothing new about public opinion being shaped in this way; the ancient Greek philosopher Plato condemned it about 2400 years ago.
Plato got us to see that our beliefs can be shaped by either rational or non-rational factors. On the rational side we have knowledge, when our beliefs are both true and we have evidence sufficient for their being true. Without truth and evidence we have only opinion.
We can also get our beliefs in a non-rational, or even irrational, way when they are formed by persuasion, rhetoric, emotional appeal, wish-fulfilment and the powers others exert on us, or we adopt beliefs that increase our desire to be happy or that comport with our interests.
We can now add modern shapers of belief such as conformational bias, brainwashing and the whole panoply of techniques of persuasion by advertising.