How does Tom Joad understand and respond to injustice in The Grapes of Wrath?

Tom Joad begins the story as an ex-convict who was sent to prison for killing a man who attacked him. He was released early for good behavior. His short sentence was perhaps an injustice, since he killed in self-defense. However, as he assures his mother, he is not bitter or “mean.” Yet he breaks parole without a second thought, leaving with his family for a better life in California. Several instances on the journey and in California cause him to worry about getting caught and being sent back to prison. Yet more than himself, he sees the injustice of how the common man is treated, especially once the “paradise” in California turns to be just as unjust, perhaps even more so, than back in Oklahoma. Though his actions are limited by his fear of being caught for breaking parole, he speaks out frequently, especially to Ma, about the injustice everywhere they go in 1930s America. With great self-control throughout most of the novel, he does not act out against injustice until he sees Jim Casy struck down when the strikers are attacked by the local police. It is not for himself that he has put himself at risk, but for another (Casy). He cannot bring himself to go on with the family because of this injustice for fear of what trouble it might bring on the others. He leaves the family and goes out on his own and effectively disappears into the unjust society.

In The Grapes of Wrath by John Steinbeck, what actions does Tom Joad take that show him growing closer to Jim Casy's beliefs?

Jim Casy is a kind of Christ figure in John Steinbeck's The Grapes of Wrath; though he was once a "real" preacher, he is closest to living out his faith when he gives that up and starts living to serve others. He comes to believe that 

"maybe it's all men an' all women we love; maybe that's the Holy spirit--the whole shebang. Maybe all people got one big soul ever'body's a part of."

He lives that out in several ways. As he travels west with the Joads, Casy is always the first to sacrifice his share or to do more than his share out of gratitude to the family. Later he has a chance to sacrifice himself by getting arrested in Tom's place (Christ analogy); while in prison, he learns that the voice of many is stronger than the voice of one as he and the other prisoners protest the quality of their food. 

While in prison, Casy realizes his calling is to help coalesce the migrant workers into unions which will make their voices stronger; it will cost him his life, but he is willing to lose his life if that is what it takes.

"Maybe there ain't no sin and there ain't no virtue, they's just what people does. Some things folks do is nice and some ain't so nice, and that's all any man's got a right to say."

Tom Joad certainly does not start out as a man who emulates Jim Casy in any way. He has been in prison and rather feels as if he is owed something in return for his loss of time and freedom. He does care deeply for his family, however, and he breaks the terms of his parole in order to help them travel west.

As he sees and experiences the injustices, his mind is softened to the plight of others. When he meets Casey again after Casy is released from prison, he is not particularly moved by Casy's ideas for organizing the workers. Over time, though, he begins to see the value of such an effort. When Casy is killed, Joad kills the man who murdered Casy and has to live in hiding. This is his thinking time. 

When he tells his mother what he feels he has to do, she reminds him that Casy lost his life in this effort, and he may, too. Joad says:

Then it don't matter. I'll be all around in the dark - I'll be everywhere. Wherever you can look - wherever there's a fight, so hungry people can eat, I'll be there. Wherever there's a cop beatin' up a guy, I'll be there. I'll be in the way guys yell when they're mad. I'll be in the way kids laugh when they're hungry and they know supper's ready, and when the people are eatin' the stuff they raise and livin' in the houses they build - I'll be there, too.

Tom Joad has begun to understand, like Casy did, that the souls of all mankind are connected and he must do what he can to make life better for everyone. He has demonstrated Casey's beliefs by how he sacrifices for his own family, and he has spent a lot of time thinking about Casy's beliefs. And now he will take action by actively working for unions among the workers. This is his grand act of sacrifice for a cause greater than himself. 

In The Grapes of Wrath, how does Tom Joad's philosophy change as he becomes Casy's spiritual heir?

Tom Joad comes to see himself as a small part of a universal whole in The Grapes of Wrath. This philosophy, which Tom has absorbed primarily from Casy, brings him to view his own suffering as unimportant in light of the hardships of others.

Casy has been attempting to start a union because he sees that people will need to stand together against the farm association that keeps wages low. Tom also sees the homeless and starving migrant farmers turn against each other as competition for the few jobs increases. All along Casy has preached that humans have only "a little piece of a great big soul", and that “a little piece of a soul wasn't no good 'less it was with the rest, an' was whole.” After Tom’s younger sister accidentally reveals that he is hiding out after killing the man who killed Casy, Tom begins to think of attempting to organize against the big farming interests. He sees that things can change only if the people band together.

While Tom Joad’s ideas are only beginning to coalesce into action by the end of the novel, his mother has acted under the same belief system all the while. She realizes that people need others, but by the same token they are under obligation to help others in need. Tom Joad has come to the same conclusion, influenced both by Casy’s philosophy and by the experiences he has as he and his family nearly starve while they are looking for work.

In The Grapes of Wrath, how does Tom Joad's philosophy change as he becomes Casy's spiritual heir?

Tom's philosophy changes in recognizing that mere survival does not represent what he wants out of life.  This change results from his work with Casy and internalizing Casy's teachings into his own personal ideology.

When the novel opens, Tom is a bit distant from the rest of the world.  Part of this might be due to the four years he has spent in prison.  Another aspect might be in his individualistic frame of reference.  Survival and endurance are the elements that defines Tom's existence.   While Tom assumes leadership of his family, helping them as best as he can, he remains a bit apart from the world around him.  

I think that Tom changes from his time with Jim Casy.  He sees his inherent goodness.  Tom recognizes Casy didn't have "an angle," possess only a truthful belief about the universality of human beings.  Tom embraces this philosophy of life.  Part of the reason he does is because he witnesses how Casy sacrifices for his values in the cause of helping others.  As Tom bears witness to this, it leaves an impact on him.  Tom says as much to his mother:

Says one time he went out in the wilderness to find his own soul, an’ he foun’ he didn’t have no soul that was his’n. Says he foun’ he jus’ got a little piece of a great big soul. Says a wilderness ain’t no good, ’cause his little piece of a soul wasn’t no good ’less it was with the rest, an’ was whole.

Casy's philosophy has embedded itself on Tom. He understands that survival is not as important as embracing something larger than oneself, to be a part "of a great big soul."  His own value system begins to grow as a result. 

With a new set of values, Tom is able to see himself more as like Casy.  He commits himself to living his life as one who is more concerned about others, even more than himself:

Wherever they’s a fight so hungry people can eat, I’ll be there. Wherever they’s a cop beatin’ up a guy, I’ll be there. If Casy knowed, why, I’ll be in the way guys yell when they’re mad an’—I’ll be in the way kids laugh when they’re hungry n’ they know supper’s ready. An’ when our folks eat the stuff they raise an’ live in the houses they build—why, I’ll be there.

In many ways, Tom sees himself as Casy's "spiritual heir."  He wants to take the work Casy was doing and expand upon it.  Tom admits that his wordss sound like he is " talkin’ like Casy."  He has inherited Casy's ideology into his own. He moves from an individualist to a more collective notion of the good.  Tom notes this change takes place because he is "thinkin’ about him [Casy] so much." 

Explain Tom Joad's change in thinking throughout The Grapes of Wrath.

We meet Tom Joad at the beginning of John Steinbeck's The Grapes of Wrath, just as he is coming home to his family after being released (on parole) from prison. Because of the Great Depression and the takeover of property by the banks, the Joads and thousand of other families have been forced out of their homes and are preparing to leave for California--the Promised Land full of opportunity. Or so they hoped.

Since he has been away, Tom knows none of this until he arrives. He should not go with his family because he is on parole; but he believes that the future is going to happen as it will, no matter what, so he travels with his family. His rather fatalistic attitude is demonstrated in his belief that one voice is powerless to effect any kind of change. 

Over the course of the novel, however, the Joads experience hardships and injustices which begin to reshape Tom's thinking. The migrant workers are treated worse than animals, food is wasted rather than used to feed starving families, and violence is the most effective method used by landowners and authorities to maintain control. When Tom kills the man who killed Jim Casy, someone who has been fighting to unite the workers in hopes of improving their circumstances, Tom is forced to stay in hiding, giving him time to reflect on the injustices which surround him.

By the end of the novel, Tom is able to articulate the beginning of his new philosophy to his mother, though he does not yet have a concrete plan. When she asks where he plans to go and what he hopes to do, Tom can only tell her he has decided that maybe a

"fellow ain't got a soul of his own, just little piece of a big soul, the one big soul that belongs to everybody, then...it don't matter. I'll be all around in the dark - I'll be everywhere. Wherever you can look - wherever there's a fight, so hungry people can eat, I'll be there. Wherever there's a cop beatin' up a guy, I'll be there. I'll be in the way guys yell when they're mad. I'll be in the way kids laugh when they're hungry and they know supper's ready, and when the people are eatin' the stuff they raise and livin' in the houses they build - I'll be there, too."

Tom's view that no one person has the ability to change the world has been transformed, because of his family's experiences and Jim Casy's death, into his belief that he is part of a greater cause and can effect change by standing with others against injustice. 

In Grapes of Wrath by John Steinbeck, how does Tom Joad grow to see himself as Jim Casy's heir?

In his essay, The Oversoul, the great 19th century American, Ralph Waldo Emerson writes of the qualities of man's soul, one of which is that it is connected to that of other men:

...that Over-soul, within which every man's particular being is contained and made one with all other; that common heart.

This same transcendental unity is what the former preacher Jim Casy intuitively acknowledges in Chapter 4 as he says,"Maybe all men got one big soul everybody's a part of." Later in Chapter 26, Tom finds Casy again, who has been in jail. He tells Tom how the men there organized and made demands that were met. Tom concludes that "It's need that makes the trouble." Unfortunately, as they talk, a vigilante finds them and kills Jim Casy, crushing his head with a pick axe. Tom reacts by wrenching the club free and using it on the man, killing him, in turn. Suddenly, Tom feels a glancing blow, so he flees. He stays in the camp while the rest of the family picks until Ruthie inadvertently refers to her brother to another girl. Consequently, Tom has to hide until Ma advises him that he must go away.

In Chapter 28, Tom recalls to Ma things that Jim Casy has said about just having a piece of a big soul. Further, he tells Ma that he wonders why people cannot all live and rule themselves as in that government camp where they have stayed earlier on their journey. This thought connects to Casy's remarks about his time in jail, and Tom decides to take up Casy's fight. He tells his mother not to worry about him because

"....I'll be ever'where--wherever you loo.  Wherever they's a fight so hungry people can eat, I'll be there. Wherever they's a cop beatin' up a guy, I'll be there. If Casy knowed, why, I'll be in the way guys yell when they're mad an'--I'll be in the way kid laugh when they're hungry an' they know supper's ready....See? God, I'm talkin' like Casy....Seems like I can see him sometimes."

After they part, Ma does not cry, for there is hope.

How does Tom Joad's character interact with the "sense of place" in The Grapes of Wrath?

I think that Tom has a unique relationship with the idea of a "sense of place" in the course of the novel.  On one hand, he represents placelesness when he leaves prison.  He has little authentic connection with people or with a place, in general.  He represents the essence of Stein's "There is no there there."  His desire to go to the family farm is one borne out of the idea that he simply wishes to be left alone.  His interaction with the sense of place is one in which he wishes to cut off connection with everything, including place, making him embodying a sense of placelessness.  In some ways, this is deliberate on the part of Steinbeck who wishes to make a statement about how society is at the time.  The lack of harnessing a sense of place is one in which individuals lose connection to one another and to those elements that matter.  The severing of bonds in placelessness emboldens those in the position of power and prevents any real connection and solidarity to be formed.  It is for this reason that over the course of the novel, Tom's sense of place begins to increase precisely at the moments when his family's placelessness also increases.  By the end of the novel, as the family struggles to establish their own sense of place, Tom has found his in the family of humanity.  Tom's connection to the larger cultural element in standing up for the principles that he sees as morally and politically right are representative of how Tom's sense of place is not tied into one particular location.  His placelessness at this point resides in the universal connection he has forged with humanity.  His decision to carry on Casy's teachings help to develop his own sense of place with all of humanity.  Tom demonstrates how his sense of place is more emotional or subjective than anything external.  In doing so, Tom shows growth and evolution, even though his sense of place is still one shown to be physical placelessness.