Two common themes interconnected throughout both "Cathedral" by Raymond Carver and "Hills Like White Elephants" by Ernest Hemingway are prejudice and ignorance, which can go hand-in-hand and even play off of each other (insofar as prejudice against a person, ethnicity, religion, etc. may be born out of ignorance of the same, and ignorance of a person, ethnicity, religion, etc. can perpetuate prejudice).
In "Cathedral," the narrator relates assorted sweeping generalizations that reveal the depths of his prejudice against people who are blind. These stem from his own ignorance:
In the movies, the blind moved slowly and never laughed. Sometimes they were led by seeing-eye dogs. (1)
In the narrator's apparent bitterness against the blind man (named Robert) and even against his own wife, he blatantly and unfairly admits that he holds Robert responsible for giving the narrator "nothing to do but wait" (4). What's perhaps worst of all about the narrator's assumptions is his admission that he has "never met, or personally known, anyone who was blind" (5). Who is he, in that case, to be making sweeping generalizations out of his utter ignorance of what it's like to be sightless?
Similarly, in "Hills Like White Elephants," the American reveals the depths of both his ignorance and his prejudice when he speaks to the girl with him about the reality of an abortion as "really an awfully simple operation," as though it were something of which he had any real notion. His ignorance is made perfectly clear when he goes on to add,
It's really not anything. It's just to let the air in.
His preconceived judgment of the medical procedure, which he himself has never experienced, constitutes prejudice and an attempt to deliberately sway his companion's view of an abortion. Finally, he adds that things will go back to the way they were after the procedure, making a further assumption that the girl's pregnant condition is "the only thing that bothers us" and "the only thing that's made us unhappy," when it's obvious from their earlier attempts at conversation—the girl creatively and imaginatively noting that the hills nearby look like white elephants to her, and the American oblivious to or even irritated by her perspective, so different from his very flat, factual one—that the girl's pregnancy is far from the only thing wrong between them. They are in two very different places in personality and outlook.