forgetfulness vs necessitation

forgetfulness

noun
  • Loss of remembrance or recollection; a ceasing to remember; oblivion. 

  • The quality of being forgetful; proneness to let slip from the mind. 

  • Failure to bear in mind; careless omission; inattention. 

necessitation

noun
  • Necessity, understood as a logical or other philosophical principle, or as a law or force of nature. 

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