As Trump continues to break promise after promise at a record rate, it is worth taking stock of how unusual this is.
Politicians keep their promises. Yes, you read that right. What makes Trump different, as an outsider, is his propensity for dishonorable behavior. Politicians, real ones, make promises on the campaign trail, and make honest efforts to keep them. When their promises aren't kept, it is due to forces beyond their control. It is the outsider-- the non-politician-- who speaks with a forked tongue. Branding China a currency manipulator? Nah. Never mind.
Jeff Fishel's work here on presidents in particular has been pretty consistent. You can track promises, and presidents generally make an honest effort to keep them. Why? This is where I reference the more general work on politicians. In particular, I frequently recommend that people read Jacobs and Shapiro's Politicians Don't Pander. The basic argument is that rather than taking insincere positions on the campaign trail, politicians look for ways to make their sincere positions electorally palatable in order to sway the electorate.
See the problem? Trump doesn't have any sincere policy positions. That's what separates him from a politician. If you look at congressional voting behavior, one of the things we learn from the behavior of retiring legislators is that they vote pretty much the same way after they decide to retire as they did throughout their careers. Why? Their voting behavior was basically sincere all along. The original research on this was done by John Lott, and it pissed a lot(t!) of people off. In fact, in one of my favorite examples of writing nonsense, Larry Rothenberg and Mitchell Sanders published a 2000 article in AJPS trying to debunk Lott's findings. They showed that retiring legislators participate in votes less frequently (Lott didn't account for that), but that the degree of ideological movement was about the same degree as what Lott always found in his many publications on the topic. But, Rothenberg and Sanders tried to make a much bigger deal of it than Lott. The magnitude of the effect they found was tiny, just like Lott. I call bullshit.
See, most politicians really do have policy beliefs, and they really do act on them. Trump isn't a politician. He didn't know what a "currency manipulator" was. Someone just fed him the line. It seemed to work for him during the campaign, as far as he could tell, so he kept using it. If he were a real politician, he would have had a real belief, and he'd stick to it. Instead, he says what he thinks will work on the campaign trail, and abandons a policy as soon as it gets inconvenient. So, all those models of sincerity?
This is what happens, Larry (and Mitchell), when you elect and outsider.