noun (n)

• the quality of being guided by sudden unpredictable impulses(noun.attribute)

  Synonym:
  unpredictability
  

  source: wordnet30
• the trait of acting unpredictably and more from whim or caprice than from reason or judgment(noun.attribute)

  Synonym:
  arbitrariness, flightiness, whimsey, whimsicality, whimsy
  

  source: wordnet30