 In 1961 Walid Khalidi referred to the transfer idea to support his idea that the Yishuv followed an expulsion policy in April and May 1948.In the 1980s, historian Benny Morris became the most well-known advocate of the existence of the "transfer idea".According to Morris, while not discounting other reasons for the exodus, the "transfer principle" theory suggests that this prevalent "attitude of transfer" is what made it easy for the Jewish population to accept it and for local Haganah and IDF commanders to resort to various means of expelling the Arab population.