He was one of the senior professors whom the University of California sought to dismiss in the McCarthy era of the early 1950s, because he refused to sign a loyalty oath — not because of any lack of felt loyalty to the United States but because it infringed on academic freedom.
他是在1950年代初麦卡锡主义时期被加州大学准备解雇的几位高级教授之一，因为他拒绝签署一份忠诚誓言，不是因为他缺乏对美国的忠诚，而是因为这破坏了学术自由。