Why do you think Dickens used ghosts to help tell a moral tale?

Scrooge has no friends, his former pertner in business is dead, and he is far removed from his nephew..... thus, Dickens employs the use of ghosts as a method of communication. If Scrooge has no moral compass, and no one to guide him, there is no one for him to listen to..... no one to interact with. The ghosts accomplish what no living being is capable of..... they can make Scrooge listen, they can force him to see, and they also allow Dickens to move Scrooge seamlessly through the past, the present, and the future.