If Hemingway may be said to be representative of modern writers, and if The Sun Also Rises can be considered a representative example of modern fiction, then we may draw some inferences about how Jews are presented and stereotyped in modern fiction with reference to Cohn. We can do this by examining some revealing textual passages in the novel. One of the best places to look for inferences about and representations of characters is in the opening pages where characterizations are established by a skilled author.

One of the first things Hemingway says about Cohn is that he is wealthy, through his father's line, and part of an old family through his mother's line. He goes on to say that Cohn never felt the Jewishness--and difference--of his ancestry until he got to Princeton.

No one had ever made him feel he was a Jew, and hence any different from anyone else, until he went to Princeton.

At Princeton, the distinguishing differences were so noted by his classmates and professors that Cohn became both enraged and self-conscious:

[He] went to Princeton. ... and it made him bitter. He took it out on boxing, and he ... [had a] painful self-consciousness ….

Hemingway, in this description, paints and supports three Jewish stereotypes: rich, ancient families, different. At the same time, Hemingway deconstructs the same stereotypes he is painting. To deconstruct, in this usage, is to undermine the very social picture being presented, thus presenting an underlying though unnoted social truth.

Hemingway undermines the stereotypical social picture he paints, in part, by providing supporting evidence for the reality of wealth and antiquity: his father has wealth; his mother has an ancient line. The supporting evidence reduces groundless stereotypes to facts of actuality. He undermines the stereotypes as well by describing Cohn's experience at preparatory school where his Jewishness was not even noted, and certainly not noted as a source of punishment to him.   

We have room for one more comment. Hemingway also describes Cohn stereotypically as being (1) valued only for his wealth (like Shakespeare's Shylock); (2) ungenerously manipulated by forceful powers (an analogy with Hitler); (3) essentially friendless, as friends were friends with a purpose.  

(1) The review commenced publication ... and Cohn [was] regarded purely as an angel (i.e., a provider of financing) ....

(2) She was forceful, and Cohn never had a chance of not being taken in hand.

(3) Robert Cohn had two friends, ... Braddocks was his literary friend. I was his tennis friend.

Yet Hemingway again deconstructs these stereotypes by describing Cohn as an individual with unique reactions and relationships: (1) Cohn finds joy in the power he feels as an editor; (2) Cohn plans a get-away from his manipulator; (3) Cohn’s friendships develop in unique ways built upon events, not upon unfounded opinions and suppositions. In sum, supposing this author and novel representative, modern fiction writers presented Jews in literature according to stereotypes but then blasted the very foundations of those stereotypes.