n.someone whose reasoning is subtle and often specious
同义词：sophist
英汉双解大词典
casuist/ˈkæzjʊɪst/
1.
N（名词）
a person, esp a theologian, who attempts to resolve moral dilemmas by the application of general rules and the careful distinction of special cases 决疑者; 尝试通过通用规则和仔细区分特殊情况来解决伦理两难问题的人，尤指神学家