KR is working on his PhD at Columbia:
All the expulsions were at the instigation of the rulers because the rulers were the only ones who had the power to expel the Jews. Some of those expulsions were kingdom-wide expulsions and some were expulsions effected by lesser nobles from the land they controlled directly: I could cite several examples from several different kingdoms. The 1290 expulsion from England was preceded by several smaller expulsions carried out by minor lords (or, in one instance, the king’s wife), for example.
I am certainly not asserting that the “royals of the MA never etc.” “Never” is a very dangerous word for historical analysis. But we’re faced with several problems here. First, the question of, as you say, “inspiration.” Why did the nobles expel Jews? Was it because of economics? Was it because of piety? Was it because of cruel whimsy? Was it because, as you suggest, the Jewish leaders irritated the Christian lords? That’s virtually impossible to answer, but trying to answer that is what part of what historians do.
The fact is that Jews were under assault, and increasingly under assault once we move into and past the twelfth century, from a number of forces, many of them with strong institutional power. We have powerful clerics speaking out against Jews (Peter the Venerable; Adamar of Chabannes; Peter Damien); we have powerful clerics defending the right of Jews to survive (Augustine; Bernard of Claivaux); and we have low-ranking clerics leading attacks on Jewish ghettos (Radulf, whom Bernard denounced); and we have lords and clerics working together to make a king act out on his quiescent anti-Semitism, as seem to have happened with England’s Henry III.
The attacks against the Jews in Germany instigated by calls for the first crusade were carried out by a heterogeneous mass of nobles and ignoble people, and during these assaults, some Jews were sheltered by the clerics.
What does this all mean? That the question of “inspiration” is too complex to answer simply, although I might add that if we think that anti-Semitism is a top-down phenomenon, that may be only because the primary sources that have survived from the Middle Ages are those generated by the powers-that-were.
I’ve always subscribed to the economic justification as a primary motivation myself – why pay your debts when you can simply banish your lender – but that explanation fails to address how the kings found it so easy to win support for their actions from the common people. It’s interesting to note, too, how KR has shifted his position from his initial “you’re wrong” response in his first email to a far more open-minded “virtually impossible to answer”.
You’ll note, however, that even if he disagrees, KR obviously understood that my contemptuous criticism was directed at specific individuals and not at a group of people or even an organization.