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In Harper Lee's To Kill a Mockingbird, Dolphus Raymond is representative of that part of society which does not follow the common societal dictates regarding the relationship between the whites and blacks in the communities in Maycomb.
It would seem to the naked eye that there are two groups in Maycomb: those like Bob Ewell, Miss Stephanie, as well as the women at the missionary tea, who believe that a black person is inferior to whites and should know his or her place. At the other extreme are people like Atticus and Miss Maudie who are respectful of the individual regardless of the color of one's skin. Both groups demonstrate their opinions in what they say and how they act.
In the middle is someone like Dolphus Raymond who does not subscribe to the "Old South's" view of a black man's place within a dominantly white (and prejudicial) society. He sees people, also as individuals, but he does not have the energy or strength of character to openly take on the society of which he is a part. He is described as...
A local man from a good white family with property who has a black mistress and children. He fosters a reputation as a drunk to give townspeople a reason to excuse his flaunting of social taboos. (eNotes)
After witnessing the terrible treatment of Tom Robinson in the courtroom, sensitive Dill becomes ill and must leave the building, and it is here that he and Scout meet the eccentric and unusual Dolphus Raymond. He carries a bottle with him in a bag to give the impression of being a drunk, a state of affairs in light of which the townspeople will overlook Raymond's choice to live with a black woman and father her children. In truth, the bag contains nothing but a bottle of Coca-Cola, and he shares this with Dill to settle the boy's stomach.
Dolphus explains the social "mask" he wears for the benefit of his peers:
I try to give 'em a reason, you see. It helps folks if they can latch onto a reason. When I come to town, which is seldom, if I weave a little and drink out of this sack, folks can say Dolphus Raymond's in the clutches of whiskey—that's why he won't change his ways. He can't help himself, that why he lives the way he does...
It ain't honest but it's mightly helpful to folks...you see they could never, never understand that I live like I do because that's the way I want to live.
Raymond explains that in a couple of years, Dill's response will be different, that he won't cry; at Dill's confusion, Raymond explains that Dill was crying:
...about the simple hell people give other people—without even thinking. Cry about the hell white people give colored folks, without even stopping to think that they're people, too.
Dolphus Raymond symbolizes the change afoot beneath the surface of what is transpiring as the South moves away from the Civil War mentality, towards a more liberated South. The changes will be slow, and hard won. Raymond, on a more basic level, may also symbolize change itself, starting with one man, like Raymond, and perhaps others like Walter Cunningham, who are able to see beyond skin color and recognize the value of the individual as a human being in his or her own right.
Dolphus is a very interesting character. We don’t really know the circumstances of his relationship with his fiancé. She may have been imbalanced, they may have been incompatible or he may have cheated on her, leading to her suicide.
In addition to Atticus, Miss Maudie and the children, Dolphus thinks outside the box of social segregation. He lives with a black woman and they have children. Dolphus pretends to be a drunk so the townspeople can make sense of why he chooses to live the way he does. On one hand, you could say that Dolphus is a bit hypocritical. If he isn’t ashamed of his family, then why hide it behind the feigned motives of a drunkard? If he really wants to bridge the gap between blacks and whites, why would he justify it with his drunk façade? Well, he does so for the same reason that Atticus knows Tom will probably be convicted. Maycomb will not change overnight. Dolphus is being realistic and by giving the townspeople a reason they can understand, he is probably making things easier on them and his own children.
Dolphus symbolizes the open mindedness that unfortunately must be portrayed as abnormal to be accepted. This is a paradox. He is open minded but feels he must disguise it. In order to be accepted, he must convey to the public that he is drunk (not in his right mind) to justify his behavior. He literally represents the marriage and equality between black and white. Maycomb accepts this because they think he is drunk. So, his acting drunk symbolizes the lack of logic of their racism.