casuistry vs equivocation

casuistry

noun
  • A specious argument designed to defend an action or feeling. 

  • The process of answering practical questions via interpretation of rules, or of cases that illustrate such rules, especially in ethics; case-based reasoning. 

equivocation

noun
  • The use of expressions susceptible of a double signification, possibly intentionally and with the aim of misleading. 

  • A logical fallacy resulting from the use of multiple meanings of a single expression. 

How often have the words casuistry and equivocation occurred in a corpus of books? (source: Google Ngram Viewer )