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.
Italy employs a very unique electoral system (well explained here). In the elections for the Chamber of Deputies, whichever party (or pre-electoral coalition of parties) receives the most votes automatically gets a majority of the seats (54 percent to be precise) in the Chamber.
In the Senate, however, this “bonus” for winning is awarded not to the party that gets most votes for the Senate nationally, but rather there is a bonus awarded for whoever does best in each of 17 regions. So it is possible for parties to get the bonus in one region but not in another.
Furthermore, in Italy the government needs to have the “confidence” (that is, be approved by) of both houses of the parliament. So the winner of the Senate is just as important as the winner of the Chamber of Deputies.
To greatly simplify Italian politics at the moment, let’s just focus on the three most relevant coalitions: former Prime Minister Silvio Berlusconi’s right-wing coalition, current Prime Minister Mario Monti’s centrist coalition and the main left-wing coalition under the leadership of Pier Luigi Bersani.
(There is also an “anti-party” movement under the leadership of comedian Beppe Grillo that is doing very well in the polls, but as for now analysts think they plan to stay in the opposition regardless of the outcome of the election, we can leave them out of this discussion.)
… The only way then that Bersani can be prevented from winning all of the regions in the Senate election is if the Berlusconi coalition wins some of them. This means that (a) if you want to see Bersani ruling in coalition with Monti and (b) you live in a region where Berlusconi is actually competitive, the best chance you have of seeing Monti in the government is if you cast your vote for the Monti coalition in the Chamber of Deputies, but for the Berlusconi coalition in the Senate.