What role does literature play in the goal of achieving social justice in John Steinbeck's book Of Mice and Men?

John Steinbeck's depression-era novel Of Mice and Men is about two traveling ranch-hands named Lennie and George. Concerning the theme of social justice, Steinbeck's most important work would probably be the much longer novel The Grapes of Wrath. Whereas The Grapes of Wrath is concerned with the fate of a large group of workers and promotes social reform (some say even socialism), Of Mice and Men takes a more indirect approach.

Lenny and George are itinerant workers, they move from ranch to ranch in search of work. To an extent, they have chosen their own fate, unlike the waves of sharecroppers who have been thrown off “their” land in The Grapes of Wrath. The social justice that George and Lennie need is of a more personal nature. Lennie is mentally disabled and would not be able to survive on his own without someone like George to watch over him. Unfortunately, Lennie's mental deficiencies land him (and George) in constant trouble: people are just not able or willing to understand someone so different from themselves.

Social justice in Of Mice and Men could only be achieved by people's willingness to understand and help each other, not by any kind of legislation or government intervention. In the end, George felt compelled to kill Lennie himself rather than let an angry mob get to him. In a socially just society, Lennie would have nothing to fear from such a mob—there would not be any mobs.

Steinbeck's goal is to show this in dramatic terms; to create characters sympathetic enough to make people take a look at themselves and how they perceive and react to others—especially others different from or less fortunate than themselves.