Definition of "presuppose" verb third-person singular simple present  presupposes , present participle  presupposing , simple past and past participle  presupposed 
To  assume  some  truth  without  proof , usually  for  the  purpose  of  reaching  a  conclusion  based  on  that  truth .  quotations   examples 
Quotations "Nay ," replied  her  companion , "what  have  I  done  for  you  to  presuppose such  a  want  of  gallantry , as  to  imagine  that  I  would  attempt  to  guess  a  lady 's  secret  before  she  thought  proper  to  communicate  it?"
1837, L[etitia] E[lizabeth] L[andon], “Asking for an Invitation”, in Ethel Churchill: Or, The Two Brides. […], volume III, London: Henry Colburn, […], page 26