Important is a problematic word, particularly when prefaced by the modifier most and especially when prefaced by the modifier only. To classify a man as important is very different from merely calling him great, because an important person needs to matter even to those who question what he's doing.

There are at least four ways an author can become semi-important: He (or she) can have massive commercial success. He can be adored and elevated by critics. He can craft "social epics" that contextualize modernity and force op-ed writers to reevaluate What This All Means. He can even become a celebrity in and of himself, which means that whatever he chooses to write becomes meaningful solely because he is the person who wrote it. There are many, many writers who fulfill one or more of these criteria. However, only Jonathan Franzen hits for the cycle. Only Franzen does all four, and he does them all to the highest possible degree. This is why Franzen is the most important living fiction writer in America, and—if viewed from a distance—perhaps the only important one. He's the most complete. But the deeper explanation for Franzen's import is something that's hard to quantify but easy to feel: For whatever reason, people just care about him more. They love him more, they criticize him more, and they think about him more. They can tell he's different, and they want that difference to matter. And Franzen understands this, which is both how it happened and why it's less implausible than it should be...