context: We doubt that Winona is a mouse. It is probably the case that Brian is gray. Chances are about even that Mary left the apple. Chances are about even that if Brian is gray, and Mary left the apple, then Fred is in the school. It is unlikely that if Brian is gray, and Mary left the apple, then Bernhard is green. It is certain that if Mary left the apple, or Winona is a mouse, then John picked up the milk.
hypothesis: It is highly unlikely that either John picked up the milk, or Fred is in the school.
valid_hypothesis: Chances are about even that either John picked up the milk, or Fred is in the school.
invalid_hypothesis: It is highly unlikely that either John picked up the milk, or Fred is in the school.
hypothesis_assertion: Either John picked up the milk, or Fred is in the school.