Much of what comes out of economics can be said to be either (a) obvious, or (b) trivial. Paul Samuelson once nominated free trade as his favourite economic finding that didn’t fall into either of these categories. Another is the median voter theorem – the notion that if there is only one issue, both parties’ policy positions will converge on the preferences of the voter in the middle of the distribution.
Now there are plenty of problems with the median voter theorem. It starts to break down in the presence of multiple issues, it doesn’t fare so well with uncertainty, and so on. But there are plenty of instances where it can help to sharpen one’s thinking. Take for example this quote from today’s Crikey email by their resident psephologist, Charles Richardson:
One further point has been suggested to me: if compulsory voting really advantages the left, you would expect the ALP to have been more successful than its counterparts in other western democracies, almost all of which have optional voting. But if anything, the reverse is true: Labor has been out of office federally for all but 16 years since 1949. Perhaps with optional voting they would have been even worse off, but the case is far from proven.
If you ignore the median voter theorem, and assume that parties don’t adapt their policies to fit voters’ beliefs, then this might be the case. But would a party that kept losing elections really not adapt its policies? Maybe for an election or two, but not forever. The real test isn’t whether compulsory voting made the ALP win more often. Instead, the question is whether the introduction of compulsory voting in 1924 pushed all Australian parties a notch to the left, something that’s much harder to measure.
In fact, the contention that compulsory voting hurts the left is pretty much demolished by a spate of studies, all of which find compulsory voting gives a small but significant advantage to progressive parties.