Arguably, it is possible to argue that ignorance is a major theme of this excellent novella. After all, the text begins with Scrooge in a position of ignorance about what others really think about him and self-ignorance about his own past and what he used to be like. What the ghosts actually do to Scrooge is move him from a position of ignorance to a position of knowledge, about both what others think of him and the reality of those who are close to him, such as Bob Cratchit's poverty and how it impacts his family. When confronted finally with his own gravestone and the kind of death he will suffer, the move from ignorance to knowledge that Scrooge undergoes is complete, and he resolves to live a very different kind of life. Note what he pledges to do to the Ghost of Christmas Yet to Come after being confronted with his gravestone:
I will honour Christmas in my heart, and try to keep it all the year. I will live in the Past, the Present, and the Future. The Spirits of all Three shall strive within me. I will not shut out the lessons that they teach.
Ignorance then is presented as a key theme in this text. Scrooge's selfishness and avarice is shown to be only possible because of his ignorance of what others truly think about him and also his ignorance of the reality of their lives. What the ghosts do is to expose him to certain truths that he has either suppressed or is ignorant of, making such a position of greed and joyless avarice impossible.