context: It is improbable that Bill dropped the milk. It is highly likely that Greg is a swan. It is probably the case that Lily is white. We doubt that if Greg is a swan, and Lily is white, then Fred left the football. It is almost certain that if Bill dropped the milk, or Lily is white, then John took the apple. We believe that if Greg is a swan, or Bill dropped the milk, then Brian is gray.
hypothesis: It is certain that either Lily is white, or Brian is gray.
valid_hypothesis: Chances are about even that either Lily is white, or Brian is gray.
invalid_hypothesis: It is certain that either Lily is white, or Brian is gray.
hypothesis_assertion: Either Lily is white, or Brian is gray.