The most difficult challenge in coming to an understanding of Dr. Adler, Tommy's father is that one must realize, first, that we view Dr. Adler through Tommy's eyes. It is difficult to trust a character's view that is constantly in flux. For instance, his son often vilifies Adler, however, we must bring the villainy into question to truly comprehend the character of Adler.
It is quite possible to see Adler as the critic Daniel Fuchs sees him, for instance. Fuchs claims that Adler is the villain of the novel. He is a man whose thoughts and actions are reduced to money and to "law and order," even to "hoarding." He refuses to help his son time and again and he seems cruel and unsympathetic. However, this may be, again, only because the reader is viewing him through Tommy's perspective. For example when Adler tells his son: "you make too much of your problems they ought not to be turned into a career," Tommy reads the following: "Wilky, don't start this crime. I have a right to be spared." Furthermore, it is Tommy who often vilifies what his father tells him and, at times, seems even to misunderstand.
It maybe simply that perhaps Adler does not want to have his son remain a "child" forever. Even Tommy claims that he is often times a "kid," when dealing with his father. Perhaps Adler simply thinks that it is time for him to solve his own problems. Adler had provided, as is evidenced in the novel, assistance in the past, while Margaret, Tommy's wife, was in college. It may be that the villainy of Adler is simply caused by a clash of character between him and his son. Adler believes in the protestant work ethic, whereas his son grew up and lives in a different America than that which was once so familiar to Adler. It is a post-war, post-depression, cold war, technological world. Adler believes in power and "success" and in rationalism. He is the "self-made man." In fact, Bellow has given Adler the name of a psychiatrist whose teachings were based on ideas of "power." Tommy, on the other hand, is, deep down, is a naturalist and an idealist.
This is not to say that Adler is not, at times, cruel, it is simply to say that his villainy and seeming tyrannical behavior is to be brought into question considering point of view.