presumption vs surmise

presumption

noun
  • An inference that a trier of fact is either permitted or required to draw under certain factual circumstances (as prescribed by statute or case law) unless the party against whom the inference is drawn is able to rebut it with admissible, competent evidence. 

  • the condition upon which something is presumed 

  • the belief of something based upon reasonable evidence, or upon something known to be true 

  • the act of presuming, or something presumed 

surmise

noun
  • Thought, imagination, or conjecture, which may be based upon feeble or scanty evidence; suspicion; guess. 

  • Reflection; thought; posit. 

verb
  • To imagine or suspect; to conjecture; to posit with contestable premises. 

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