求解释一个长难句

墨墨墨南

该句子是杨鹏长难句里面的
His thesis works relatively well when applied to discrimination against Blacks in the United States, but his definition of racial prejudice as "racially-based negative prejudgments against a group generally accepted as a race in any given region of ethnic competition," can be interpreted as also including hostility toward such ethnic groups as the Chinese in California and the Jews in medieval Europe.
实在是愚笨，不知道这里的“but”表达的转折是什么？感觉前后并没有意思的转折啊。

sdy0803

前面说他的理论很好，后面指出理论的定义有瑕疵，所以有个转折嘛。

Vivan。

扣掉引号里的先不看就好了，引用没啥用的