As you watch the Italian election results come in this weekend, ponder the following seemingly contradictory statement: for some Italians in some regions of the country, the vote that is most likely to lead to the policies they most prefer being enacted by the new government would involve voting for their preferred party in the elections to the lower house of the Italian Parliament (the Chamber of Deputies) but for their preferred party’s worst enemy – the party of Silvio Berlusconi – in the upper house (Senate) elections. How could this be? The answer lies in what political scientists call “strategic voting”. To understand strategic voting, it is first necessary to understand “sincere voting”. A sincere voter ranks the parties or candidates, and then casts his vote for his top ranked party: the vote is a “sincere” reflection of the voter’s top preference. A strategic voter, however, asks some sort of additional question before deciding whether or not to cast his vote for his top choice. Usually this question is “will my vote be wasted”? The easiest way to waste a vote is to cast it for a candidate who has no chance of winning: think a vote cast for Ralph Nader, for example, in the 2000 US Presidential elections. Occasionally, a vote can also be wasted by casting it for a party that has already won an election, but needs a coalition partner to get above a minimum threshold in order to govern. Strategic voting then might dictate voting not for your preferred party, but for its needed coalition partner; such behaviour is said to explain the unexpectedly strong performance of the Free Democrats in the recent German regional election in Lower Saxony. But there is another type of strategic voting, trying to influence policy outcomes. Social scientists Howard Rosenthal and Alberto Alesina have demonstrated how it can be perfectly rational for Americans to vote for one party in a presidential election and another party in legislative elections if one’s policy preferences are located between the two parties. The current Italian elections, however, take this form of strategic voting to a whole new level, as they provide a set of incentives for voters to vote for and against the same party in one set of legislative elections to pick a single government. Here’s how.