A three-cornered election: the ancient Athenian solution
One of the smart ideas of the ancient Athenian democracy was the system of ostracism. If the people wanted to decide between the policies of two different politicians, and they were deadlocked -- they had a vote and simply exiled one of them.
Every year from the beginning of the fifth century BC, the Athenians were asked if they wanted to hold an ostracism. If they voted yes, then another vote followed in which people scratched the name of the politician they wanted to get rid of on a piece of pottery (an "ostrakon").If more than 6000 people voted, the the one with the most votes was sent into "honourable exile" for ten years. It was one solution to policy dilemmas.
It wasn't perfect. A cache of almost 200 ostraka has been found down a well in Athens, each with the name "Themistocles" written on them (in a limited number of hands; they're pictured at the top of this post). It's a clear hint that the system was manipulable. "Get your Themistocles ostrakon here" someone must have been shouting -- or, given the illiteracy of much of the Athenian people, "Get your Cimon ostrakon here" -- and you actually got a Themistocles ostrakon, without realising it.
But it worked well enough, for almost a hundred years. Until there was a three cornered fight.
In c.415 BC a man called Hyperbolus was in an ostracism competition, with two "bigger guys", Nicias and Alcibiades (who were the cause of the real policy dispute).
It's not a strategy that has been successfully used, yet, by Cameron and Brown against Clegg. In fact, I write this as I watch the second debate, Brown has just targeted the other two (comparing them to his squabbling "boys").
But then he needs the Lib Dems to do well enough to keep the Tories out. Which is why it's different from the 415 ostracism. Athenian ostracism wasn't based on constituencies.It was all a matter of the popular vote.