pessimism vs skepticism

pessimism

noun
  • A general belief that bad things will happen. 

  • The condition of being pessimal. 

  • The doctrine that this world is the worst of all possible worlds. 

skepticism

noun
  • The practice or philosophy of being a skeptic. 

  • Doubt or disbelief of religious doctrines 

  • The doctrine that absolute knowledge is not possible 

  • A studied attitude of questioning and doubt 

  • A methodology that starts from a neutral standpoint and aims to acquire certainty though scientific or logical observation. 

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