A common (and fair) complaint about Donald Trump is that he is vague on how he would actually govern as president. This was a major complaint among conservatives throughout the primaries. Does he support Planned Parenthood or not? How does he really feel about the government’s role in health care? He has made many seemingly contradictory statements that can be interpreted in multiple ways. One could use this as evidence that Trump has no idea how he will deal with these issues. A more generous explanation is that ambiguity was a deliberate strategy designed to increase his appeal.
My own research rarely touches on campaigns per se, but I was vaguely aware of the research on the use of "strategic ambiguity" by candidates. Since I have been trying to make sense of the Trump campaign, especially the reasons for his success so far, I thought it time I gain some more understanding on the subject. It turns out that political scientists have been discussing this a lot longer than I realized. I've read Anthony Downs' classic book, An Economic Theory of Democracy(1957) at least three times, but for some reason had completely forgotten his argument about political parties being deliberately ambiguous.
Thus political rationality leads parties in a two-party system to becloud their policies in a fog of ambiguity. True, their tendency towards obscurity is limited by their desire to attract voters to the polls, since citizens abstain if all parties seem identical or no party makes testable promises. Nevertheless, competition forces both parties to be less than perfectly clear about what they stand for. Naturally, this makes it more difficult for each citizen to vote rationally; he has a hard time finding out what his ballot supports when cast for either party. As a result, voters are encouraged to make decisions on some basis other than issues, i.e., on the personalities of candidates, traditional family voting patterns, loyalty to past party heroes, etc. But only the parties on issues are relevant to voters’ utility incomes from government, so making decisions on any other basis is irrational. We are forced to conclude that rational behavior by political parties tends to discourage rational behavior by voters.[i]
So there you have it. This does not prove that Trump had some kind of grand strategy when he made baffling and contradictory statements about policy. But if he did, there were good reasons to expect it to be successful.