The collapse of Europe's once-dominant socialist political parties has been apparent for years, and it continued last year. By now, however, the left has the information it needs to pull out of its nosedive. It just has to start using it.

The crushing defeats of 2017 - the near-death experience of the Socialist Party in France, the deflation of the Social Democrats in Germany and the Labour Party in the Netherlands, the shrinking of the entire left wing in the Czech Republic - apparently weren't enough of a wake-up call. The defeated parties have not regained popularity, and some, like the German Social Democrats, have slid further down in the polls.