In The Educated Imagination, Northrop Frye argues for a social function of literature:
So, you may ask, what is the use of studying the world of imagination where anything is possible and anything can be assumed, where there are no rights or wrongs and all arguments are equally good? One of the most obvious uses, I think, is its encouragement of tolerance. In the imagination our own beliefs are also only possibilities, but we can also see the possibilities in the beliefs of others. Bigots and fanatics seldom have any use for the arts, because they're so preoccupied with their beliefs and actions that they can't see them as possibilities. (pp.77-78)
Note that Frye does not say, or suggest, that literature has the power of changing people who are already intolerant. Literature's encouragement of tolerance will have, in most if not all cases, no effect on bigots and fanatics, the most intolerant among the intolerant. Although bigots and fanatics do see others' beliefs as possibilities, they see those beliefs as mere possibilities, while seeing their own beliefs as the truths. If they do read literature, they will see more possibilities as a result. However, the more possibilities they see, the more they may think what they see are mere possibilities, and the more they may assure themselves that their own beliefs are the truths. Not only does literature fail to encourage bigots and fanatics to be tolerant, it may even encourage them to be more intolerant!
But isn't it part of the concept of belief that to believe that p is to believe that p is true? Whether a person is a bigot (or fanatic) or not, he has to take what he believes to be true --- no one can consistently believe that p without taking p to be true. So, how are we different from bigots and fanatics in this respect? In this respect there is indeed no difference; the difference lies in somewhere else: bigots and fanatics are so committed to their beliefs that they are not capable of taking seriously the possibility that their beliefs are false. They cannot, as it were, detach themselves from their beliefs, while we can ours if we try.
According to Frye, literature encourages tolerance by means of encouraging detachment of this kind:
What produces the tolerance is the power of detachment in the imagination, where things are removed just out of reach of belief and action. Experience is nearly always commonplace; the present is not romantic in the way that the past is, and ideals and great visions have a way of becoming shoddy and squalid in practical life. Literature reverses this process. (p.78)
Through the imaginative lens of literature, we can see even our own beliefs from a certain psychological distance, which may be sufficient for making us more tolerant, even if in the end we do not give up any of our beliefs.