context: It is highly unlikely that John dropped the milk. Chances are slight that Winona is a mouse. We believe that Mary is in the hallway.
hypothesis: It is impossible that winona is a mouse, and John dropped the milk.
valid_hypothesis: It is impossible that winona is a mouse, and John dropped the milk.
invalid_hypothesis: It is probable that winona is a mouse, and John dropped the milk.
hypothesis_assertion: Winona is a mouse, and John dropped the milk.