I'll finish the post with Philip Spencer on left anti-semitism:
And finally, we need to argue that anti-Semitism is wholly unacceptable, that no organisation or movement on the left should tolerate any expression or manifestation of anti-Semitism. It was once (foolishly) said by a great socialist, August Bebel, that “anti-Semitism is the socialism of fools”. It was not and is not any such thing. It is not any kind of socialism at all, of fools or anyone else. A left that tolerates anti-Semitism, that legitimates it, that colludes with it for purposes of mobilisation, as it socialises a new political generation, is in danger of wrecking itself politically and morally.