In Scout's eyes in Harper Lee's To Kill a Mockingbird, what is Atticus's chief fault?
In Chapter 10 of Harper Lee's To Kill a Mockingbird, we learn what Scout sees as Atticus's chief fault soon after the children receive the air riffles they had asked for as Christmas gifts. In Scout's own words, "Atticus was feeble; he was nearly fifty."
Scout sees Atticus's age as contributing to his feebleness because, being young herself, she thinks that 50 is very old. In addition, when his children ask him why he is so much older than the parents of other kids their age, he responds that "he got started late," and Scout and Jem see this statement as a reflection "upon his abilities and manliness." Scout and Jem see Atticus's abilities as limited due to his age in several ways.
One example of his limitations concerns Atticus's ability to play with his children. Atticus is able to play keep-away with Jem anytime, but whenever Jem asks him to play tackle football, Atticus declines by saying, "I'm too old for that, son," which disappoints Jem greatly since he loves football so much and other fathers are able to play with their sons.
Other examples of what Scout perceives to be his limitations concern his job and his physique. Scout thinks Atticus has a very boring job as a lawyer. In her eyes, he doesn't do anything exciting like "drive a dump-truck" or work as a "sheriff." Instead, all he does is sit in an office all day long, which could not "possibly arouse the admiration of anyone." His physique further speaks to his feebleness and old age since he wears glasses and is almost blind in one eye.
In short, at the beginning of the story, the Finch children see their father as a dull, boring, feeble, and an old person.