胡適在1957年《胡適日記》兩次寫下「妄人」，一次指旅港記者曹聚仁，另一次指褚定民，他為何如此書寫的原因至今未明。本文嘗試探索蔣中正、胡適互動關係中的美國因素，以解釋胡適為何有此一判斷。雖然褚定民在1950年代初期、中期的香港「第三勢力」中是位無名小卒，他發表的言論剛好指陳出蔣中正、蔣經國父子權力基礎中的政治猜疑，他發行的小冊子最終在臺灣遭到執政當局查禁。此舉則增添褚氏在香港的政治知名度。本文作者結論指出，當蔣中正、胡適在「反共」議題一致並互動緊密時，「美國因素」不會形成負面因子。只要他們抱持不同的政治理念，「美國因素」就加深了他們的分歧。這是我們觀察蔣、胡互動時不能忽略的因素。

In his diaries written in 1957，Hu Shih used the term ＂arrogant man＂ twice, once referring to Chao Ju-ren （曹聚仁），a Chinese journalist sojourning in postwar Hong Kong, and once to Chu Ding-min （定民）.The reason Hu used such a term is unknown. This article tries to explore the US factor in Hu's interactions with Chiang Kai-shek and to explain why Hu made such a condemnation. Although Chu Ding-min was an unknown figure in Hong Kong's ＂third force＂ during the early and mid-1950s, his public speech suggested mistrust of Chiang Kai-shek's and Chiang Ching-kuo's political power base. His pamphlets published in Hong-Kong were banned by the authorities in Taiwan, thereby enhancing Chu's political reputation in Hong Kong. This study finds that the ＂US factor＂ was not a negative element in Chiang and Hu's interactions on ＂anti-communist＂ unanimity. Since they had different political views, their divergence could have been deepened by the US factor, a possibility that should not be overlooked in studying their interactions.