From lionheart's Indy link – something we've discussed before:
And it’s the fact that Trump is a political liar. The lies are not simply intended to deceive; they are, as the Russian dissident Masha Gessen has argued, a brute assertion of the primacy of power over truth, of a conception of power that simply does not recognise the authority of truth.
Trump says something that is untrue, that people around him know is untrue, that he himself knows to be untrue, and which he knows they know is untrue. Why? As a statement of his authority and the absolute nature of it. As the Missouri audio also reveals, the job of his aides, when a lie is told by their master, is to locate some evidence that his assertions are, in fact, correct.
By forcing his spokespeople and subordinates to repeat, defend or rationalise his blatant falsehoods in public, he destroys their own reputations and their own sense of self-respect.
(The article it links to by Masha Gessen also looks interesting, though I haven't read it properly: www.motherjones.com/politics/2017/10/trump-and-putin-strong-connection-lies/)