It was a bitter weekend for Europe. In elections across the continent, voters expressed displeasure with their political leaders. The results were no surprise and reflected deep concern about economic policy and, especially, the impact of the austerity measures that have been adopted to fight off insolvency.

While tough choices are necessary, they are unsustainable if they do not enjoy public support. The only question now is how deep the disaffection goes: If voters do not believe that their political system is fair, then the results are likely to shape not just the composition of European governments but their very structure.

The highest-profile election last weekend was the second round of the French presidential ballot, in which Socialist Francois Hollande upset incumbent Nicolas Sarkozy. Mr. Hollande will be the first Socialist to occupy the Elysee Palace since Francois Mitterrand's 14-year presidency that ended in 1995. The election was not really close: Mr. Hollande claimed a victory margin of 51.9 percent to 48.1 percent. Mr. Sarkozy conceded defeat 20 minutes after the last poll closed.