When I first started professionally monitoring and studying anti-Semitism almost 30 years ago, there was, broadly speaking, a shared understanding of what it was. True, historians differed over a precise definition - quite understandably, given that the term was coined only in the 1870s, and was then used to describe varieties of Jew-hatred going back 2,000 years. There was also a degree of political manipulation of the phenomenon, with both the right and the left blaming each other for causing it.













