I love this post, and having been briefly involved with debating societies, it makes me think about how the most successful politicians (who practise the types of debating tricks where you learn how to support an argument that you may not actually believe in) operate.
I would in fact, argue that most successful politicians are liars. They have to be, in order to progress their careers. The ones who speak the truth stay on the backbenches.
I read a very interesting post from @luzcypher recently, which discusses the methods that are used to spread fake news. I looked up one of the sources in his post, about "the 25 rules of disinformation" – and it is so revealing. I don't think this is an actual rule sheet – it's more of a guide to how politicians and campaigners (and social media trolls) press their point in public, and how they aim to slay their opponents' arguments rather than adhering to logic or rationality.
Sadly, it often works!