Richard: Because it fails to meet the fundamental requirement of art—that it represent—abstract art will eventually be seen as an aberration.
Richard's Explicit / Implied Claims
1. A fundamental requirement of art is that it represent 2. Abstract art fails to represent 3. Abstract art will eventually be seen as an aberration. 4. It will be seen as an aberration because it doesn't meet the fundamental requirement of art.
Jung-Su's Position on those Claims
1. No comment. Nothing about fundamental requirement. 2. Disagrees? She says that whatever others might come to say", as a noncommittal nod to the future. One day others might come to say abstract art is aberration, who knows? What we do know is that today it's not an aberration; it's part of the mainstream. 4. Since there's no comment on #3, there's definitely no comment on the specific causal mechanism that would lead to #3 coming to pass.
Goal
It looks like claim 2 is the only area where Jung-Su disagrees. So let's look for an answer about whether or not abstract art represents stuff.