Pretty solid essay by Paul Johnson, who argues that anti-Semitism has all the hallmarks of a form of mental illness. However, I think the comparison with anti-Americanism at the end is an overreach on his part. But still, well worth reading, especially since it has sharp observations like this:
Asked to explain why they hate Jews, anti-Semites contradict themselves. Jews are always showing off; they are hermetic and secretive. They will not assimilate; they assimilate only too well. They are too religious; they are too materialistic, and a threat to religion. They are uncultured; they have too much culture. They avoid manual work; they work too hard. They are miserly; they are ostentatious spenders. They are inveterate capitalists; they are born Communists. And so on. In all its myriad manifestations, the language of anti-Semitism through the ages is a dictionary of non-sequiturs and antonyms, a thesaurus of illogic and inconsistency.
Oh, and a handy warning from your host here: I have no patience with casuists who try to redefine anti-Semitism. Absolutely none. Ditto statements which indicate hatred of Jews, mention of alleged Jewish conspiracy theories and the like, all of which activate my hair-trigger delete and ban policy.