Civil war parties shed voters in tough times but fail to woo them back again
Over time voters have punished governments more for economic failings, but show no signs of crediting them when things go well
Possibly the best-know quote in recent political history is: "It's the economy, stupid." It was coined almost a quarter of century ago by an adviser to Bill Clinton during his first presidential campaign in 1992. The advice to Clinton was to hammer relentlessly on economic issues (the US unemployment rate had been rising since the summer of 1990), and by doing so he would unseat incumbent George Bush Snr.
There is a long tradition, going all the way back to Karl Marx, if not before, which holds that economic factors determine political outcomes. That tradition now has a new variant.
Across the rich world, there has been an upsurge recently in discussion of the downsides of economic globalisation. In developed countries, a growing number of analysts and commentators are attributing political changes to economic factors - specifically a rise in the numbers of people who lose out because of the increase in cross-border economic activity.