The title character of the Arrowsmith is Martin Arrowsmith, a young man whose curiosity and stubbornness make him perfect for the realm of scientific research. And yet, Martin becomes distracted and often sways from his path. He is constantly criticizing the commercialism of the medical profession as well as the "machines" that are made in the medical school "mills."

And yet, Martin is, himself, tempted by the very things he criticizes: money, success, fame, notoriety, respect. When, for example, Martin is forced to make a speech in Nautilus, Martin thrives on the respect of the audiences and gets quite a thrill from the applause. It is Leora that has to bring him down to Earth. Later, Martin, seems to ease in to the lap of luxury, taking limousine rides to work, for example, while he is married to Joyce Lanyon. And yet, though Martin sways and attempts to fit into high class society, into Joyce's lifestyle, and into the world of institutions and social gatherings, Martin is nonetheless always an outsider and only truly happy when he is able to work in the lab.

Martin's curiosity for science and "truth" begins at an early age, and it is what Gottlieb so praises in him. This curiosity is what saves him and keeps him going, even if he occasionally ventures off his track. Martin holds within him a plethora of contradictions that are difficult to fuse, and this is epitomized by his love for both Dean Silva ("the good doctor") and Max Gottlieb (the stern and unrelenting scientist). These contradictions are also exhibited in Martin's love for Leora in spite of the temptation of girls like Orchid and Joyce. His name encompasses all of these contradictions. The name Arrowsmith, upon first reading, may seem to recall only the "arrow." The reader believes that the name is meant to symbolize a straight and stubborn path. Yet, Martin's name is not Arrow, it is Arrowsmith, representing the person (craftsman) who makes the arrows—the person who melds it out of difficult steel or iron. Further, because this is a novel of a single man's education and personal development, this name suits Martin because it illustrates that Martin is "learning" how to make his arrows and how to create that straight path out of the contradictions and the tough iron that life gives him.