Answer:
They believe that the position of the Caliph is not hereditary and that Mohammed did not single out anyone to succeed him.
Explanation:
The Sunni's and the Shia's are two divides in the Muslim religion that have differing views about the position of the Caliph who is the leading religious and political leader of the Muslim community.
While the Sunni's believe that there is no appointed successor of Mohammed and that the position of the Caliph can be given to anyone, the Shias believe that Imam Ali is the rightful successor of Mohammed. They also believe that the office of the Caliphate should be passed through the descendants of Fatima, the daughter of Mohammed.