You know your ideas have had some success when they become conventional wisdom to the extent of being misunderstood.
It is a truism of political science that what happens in election campaigns doesn’t make any real difference. By the time the formal campaigning starts the voters pretty much know where they stand. They then have to wait patiently (or impatiently) for a few weeks while politicians and journalists get their knickers in a twist over imagined gaffes and surges, swings and comebacks. Once that is all over, people put their crosses just where they were going to put them anyway.
Almost right. But what Runciman didn’t realize was that this “truism” (also known as “research“) relies on their being a two-candidate election with clearly distinguishable candidates. The recent U.K. election, with three contending major parties and lots of talk about tactical voting, didn’t fit that script.
To put it another way, when the race is between candidate A and candidate B, you might as well vote for the candidate you prefer, no matter who happens to be in the lead–and the evidence is that people do just that. I’ve not seen evidence of any bandwagon effects in races between two candidates of opposing parties. But when the race is between A, B, and C, then, yes, your vote choice can definitely be affected by the possibility that C really has a chance of winning.
To put it yet another way: Elections are inherently more unstable when more than two candidates are involved.