premise: Bob The Bottle Cap Collector<br>Bob's was in the mood to find bottle caps. Today, he went to the beach to find some buried ones. He used his metal detector to find them. At the end of the day, he detected something on his detector. The detector found the most valuable bottle cap ever.
hypothesis: If bottle caps were made of rubber, the metal detector would not be able to find them.
reason: A metal detector only detects items that consist of metal and so are unable to detect rubber.