How does Tim Johnson (the dog), a wounded creature, resemble both Boo Radley and Tom Robinson?
Atticus shoots a rabid dog earlier in this story and seems a hero to his children then. The incident is symbolic in several ways.
The other answer her outlines some strong valid points. I'd like to make it a little more basic: all three of them are innocent victims of something beyond their control.
Ol' Tim Johnson is a rabid dog. He neither asked for the disease (hydrophobia) nor did he do anything out of the ordinary to contract it. Society, though, has determined that animals with this disease are a threat to its well being. There is no cure to be given, so the course is set--the innocent dog must be removed from society for the greater good.
Tom Robinson is a black man living in the South, and that is the circumstance which is out of his control. He lives a quiet life, helping others when he's able, yet his color creates a scenario in which causes him to be a scapegoat. Society has determined that a black man's word can not be believed over any white person's--especially in the case of rape. He is innocent but must, like Ol' Tim Johnson, be removed from society.
Boo Radley is a recluse; though we don't know the exact cause, he is socially cippled. He is the subject both of specualtion and the cruelties of being different. He is persecuted by the Finch kids and Dill, and we presume they are not his only tormentors. Boo has done nothing to deserve this treatment, yet he is branded as some kind of a freak by society. No one shoots him, as they do the other two in fact, he is kills Bob Ewell to protect jam); but he is a target nonetheless.
It's true that they aren't all equal in their scope and value to the story; nonetheless, all three of these characters serve as visible repetitions of the mockingbird theme--those who have done nothing but are punished or victimized because of things beyond their control.
haha i think you mean the "rabid dog"... not rapid.
Interesting question though.
Normally the rabid dog is related to or is chosen to symbolise prejudice. And how Atticus so willingly and skillfully shoots it down. And just like prejudice, it "is just as dangerous dead as alive," whether prejudice is alive = when tom robinson loses because of prejudice. or dead = even if tom robinson wins prejudice in rumours against him will spread throughout the town. Yeah.
Back to how Tim Johson relates to boo radley. Boo ended up the way he is because of his misadventures when he was a teenager. He did not know at that time the consequences of his actions would be so big. The rabid dog too probably didnt knowingly get his rabies. As a result, Boo Radley is forced out of the society by his dad for those misadventures as tim johnson is for getting infected with rabies.
Both are also feared by the society. Boo Radley is seen as a "molevolent phantom", while the dog is seen as rabid. We see this fear when we see that the doors of the neighbourhoods lock up as the dog approaches, and "the trees were still, the mockingbirds were silent, the carpenters at Miss Maudie's house had vanished." The fear of Boo is too shown by the actions of the society, for example "A Negro would not pass the Radley Place at night, he would cut across to the sidewalk opposite and whistle as he walked." and "A baseball hit into the radley yard was a lost ball and no questions asked" - children are so scared of the molevolent phantom that they don't even dare ask for their ball back - "from the Radley chicken-yard tall pecan trees shook their fruits into the school yard, but the nuts lay untouched by the children".
maybe you could also say that tim johnson could think straight because of his disease, just like the maycomb people who cant think staright cos of prejudice.
both of the characters are victims of rumours that are not true.
(quotes available in book)