I would say society is only 50% culpable for what happens at the end of Book 1. This is because Bigger is fully capable of making his own decisions and defining his own beliefs. He did not, because he is black, have to believe that Jan and Mary were making fun of him because of the color of his skin. No one has forced him to believe that, which is why it's not society's fault; however, this can be blamed on society because of the fact that it would be the common norm for whites to make a black ashamed because of his skin. Bigger did not have to go along with Mary and Jan's plans of sitting in the backseat getting drunk while he drove around, Bigger could have turned around and told Mrs. Dalton. He may have been fearful that Mary would then hate him, but I'm sure Mrs. Dalton would have respected him more... if she believed Bigger's story over Mary's. Society is, again, only 50% responsible for this action because a white person would believe another White's story over any black man, except we know the Dalton's to be different, so maybe not. The alcohol was apparent and Mrs. Dalton could smell it on Mary, therefore if Mary had made some remark about Bigger being in the room, Mrs. Dalton could have easily perceived it to be drunken murmuring that meant nothing. To blame it all on society wouldn't be fair because Bigger is his own person, he does not have to follow society's rules.