Turner , in his `` Frontier Thesis '' ( 1893 ) , theorized Statement that the frontier was a process that transformed Change Europeans into a new people , the Americans , whose values focused Aiming on equality , democracy , and optimism , as well as individualism , self-reliance , and even violence Violence .

He theorized Know it was a process of development Cause_to_make_progress : `` This perennial rebirth , this fluidity of American life , this expansion Expansion westward ... furnish Supply [ es ] the forces Causation dominating American character . ''

The investigation was unable to determine Deciding conclusively what had caused the horizontal stabilizer trim to be set Placing improperly , but theorized Coming_to_believe that the most likely cause was an aircraft system malfunction Motion .