The reading passage holds that three major functions of the carved stone balls. However, the professor argues that none of the three theories are very convincing.
Firstly, according to the reading passage that the carved stone balls were weapons used in hunting or fighting. Whereas the professor thinks that common Heolithic weapons such as arowheads and hand axes had sign of wear. If the stone balls had been used as weapons, there would be cracks and pieces broken off as well. However the surfaces of the balls are well preserved and only little or even no damage were shown. Therefore, weapons cannot be one of the functions of the stone balls.
Secondly, the reading passage suggests that the carved stone balls were used as part