context: There is a better than even chance that Brian is a swan. It is highly unlikely that John went to the office. It is probably the case that Sandra got the football.
hypothesis: It is certain that either Sandra got the football, or Brian is a swan.
valid_hypothesis: Chances are about even that either Sandra got the football, or Brian is a swan.
invalid_hypothesis: It is certain that either Sandra got the football, or Brian is a swan.
hypothesis_assertion: Either Sandra got the football, or Brian is a swan.