One of the more bizarre aspects of the recent US Presidential election campaign was the ability of Donald Trump to tell more lies and half-truths than most of us would do in a lifetime and yet still claim that Hilary Clinton could not be trusted in office. Even more bizarre, was the fact that he got away with it! How can we possible make sense of this? Some might point to a dumb electorate. I think we can learn more by looking at guilt aversion.
The concept of guilt aversion was formally introduced into game theory by Pierpaolo Battigalli and Martin Dufwenberg with a paper published in the American Economic Review in 2007. (I should also mention a paper by Gary Charness and Martin Dufwenberg in Econometrica in 2006.) The basic idea is that a person only needs to feel guilt if they disappoint the expectations of others. To illustrate, consider Donald Trump's 'promise' to lock up Hilary Clinton. Nobody realistically expects Trump to fulfil this promise. But, because nobody realistically expects him to lock her up then he needs to feel no guilt making and breaking the promise. It is all cheap talk.
If everything is all cheap talk then Trump can say what he likes, nobody can believe it, he can predict that nobody will believe it, and everything works out fine! And it is noticeable that post election none of his supporters seem particularly upset that many campaign promises have fallen by the wayside. The only promise people seem to really care about is his promise of trying to make America great again. If he does not fulfil on that promise then he really should feel guilt.
Hilary Clinton, by contrast, seems to have been judged by different standards. She is expected to tell the truth and nothing but the truth. Which is presumably why the email controversy took on such a huge importance. Any sign that she had let down expectations was taken as a signal that she could not be trusted.
Ultimately, though, this meant we have a good idea what Hilary was intending to do as President. With Donald Trump, by contrast, we don't have a clue. We have a good idea about some things he will not do - lock up Hilary, build a wall on the Mexican border etc. - but beyond that it is uncertainty. Usually uncertainty is a bad thing and Trump would not have had a chance. We seem to live in a world, however, where uncertainty is becoming ever more appealing to voters. That opens the door for a whole lot more bullshit in the future.
Interestingly, the evidence of guilt aversion in the experimental lab is mixed. In particular, there is a fair amount of evidence for lie aversion. The basic idea here is that a person feels bad if they lie. In this case it is irrelevant whether or not anybody expects the person to keep their promise, the person simply does not like to break their promise. So, Donald Trump would feel averse to making a promise he knows he cannot keep. Which does not sound much like Donald Trump.