inflexibleness vs volition

inflexibleness

noun
  • Obstinacy of will or temper; firmness of purpose that will not yield to importunity or persuasion; unbending pertinacity. 

  • The quality or state of being inflexible 

volition

noun
  • The mental power or ability of choosing; the will. 

  • A conscious choice or decision. 

  • A concept that distinguishes whether or not the subject or agent intended something. 

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