Answer:
The danger of optimism is to see things in a way they are not. It is dangerous because t can't fool someone into thinking things are working out when they are not.
Skepticism can lead to apathy. When a person does not believe in what other people say they cannot relate to one and other. A extreme skeptical postition would lead no a very difficult way of leaving.
Candice at first sustained a very optimistic position, and after all the tragedes he started being skeptcical to the optmisitc position. This allowed her to questioned what he believed before.
Explanation:
Candide is an example of an optimistic person. A lot of terrible things happened to him and to his loved ones, and despite that, he still believed things are good. Loosing his friends and being beat up among other things. He wanted to believe in Pantagon's theory of optimism and he did, until he couldn't any more.
After some time in the plot, reason comes to him and he thinks of optimism as a mania of seening good when things are actually pretty bad.
Candice is a innocent and naive person, his optimism made him like this. An extreme optimistic position can lead to a naive postition in life.