Why did the ghost of Christmas present told scrooge about the evils of ignorance and want?

Its was the underlying message Dickens wanted to convey. The Ignorance of the situation where those with moe did not know or want to know about teh deprivation and poor living of other humans around them and the depth of teh wanting - Food, clothing, somewhere safe to sleep, the care of teh young and even basic health - Using the story Scrooge represents those that have money and through him Dickens shows what is happening around Britain at that time