The Generation Gap
Long before hippies rebelled against their square parents, there has been a generation gap. Important to note is that in most cases the true width and depth of the gap was glossed over in confrontations between parents and children. What you could let hang out in the 1960’s home was kept repressed in the 1920’s home. Then the younger generation went out and listened to jazz and drank Prohibition booze and became a flapper or dated them. What Fitzgerald did in his novel was force the unspoken out into the open and in the process one generation learned they were being blamed for everything that happened up until the end of World War I by the next generation. They didn’t like what they heard and they didn’t like This Side of Paradise for saying it.
Identity
The question of establishing an identity and questioning identity and confusion over identity permeates throughout the novel. The return to a fundamental Amory is only possible after he chucks the whole thing about adopting conformity as a route to success. Rosalind bases one of the most important decision in her life on a construct of identity that views her aesthetically pleasing features as the very soul of her identity.
Egotism as an Expression of Individualism
A distinct and often distasteful strain of narcissism runs through the novel. Just about every character is exceptionally self-involved and seems to place themselves at the center of the universe. Important to realize is that this is not some manifestation of a solipsism in which everything is a construct of the mind; the obsession with the Self was a dominant theme throughout the Modernist movement and was intent and should be taken less as a rejection of the importance of everything else and more as a specific rejection of traditional values and outmoded conventions for the purpose of redefining themselves outside of those imposed restrictions that no longer served a purpose in modern American life.
Maturity plus Compromise equals Hypocrisy
Nobody much wants to play the adult in Fitzgerald’s novel. And why would they? Every action, every decision and every moment of contemplation leads to just inescapable conclusion about growing up: it is filled with disillusionment of compromise and turns even the most steadfast idealist into a hypocrite.
