context: We doubt that Fred left the football. It is certain that Lily is white. Chances are slight that Mary moved to the office. It is likely that if either Lily is white, or Fred left the football, then Brian is a lion. It is unlikely that if Lily is white, and Fred left the football, then Julius is a swan. There is a better than even chance that if either Mary moved to the office, or Fred left the football, then John picked up the milk.
hypothesis: Chances are about even that either Brian is a lion, or Mary moved to the office.
valid_hypothesis: Chances are about even that either Brian is a lion, or Mary moved to the office.
invalid_hypothesis: There is almost no chance that either Brian is a lion, or Mary moved to the office.
hypothesis_assertion: Either Brian is a lion, or Mary moved to the office.