context: It is probably not the case that Mary got the milk. It is highly likely that Greg is green. Chances are about even that Winona is a wolf. We doubt that if Greg is green, or Mary got the milk, then John left the milk. It is unlikely that if Greg is green, and Mary got the milk, then Lily is white. There is little chance that if Greg is green, or Mary got the milk, then Brian is gray.
hypothesis: It is impossible that john left the milk, and Lily is white.
valid_hypothesis: It is impossible that john left the milk, and Lily is white.
invalid_hypothesis: It is almost certain that john left the milk, and Lily is white.
hypothesis_assertion: John left the milk, and Lily is white.