Carlson is a ranch-hand who is defined by his unsentimental nature. As an experienced worker, Carlson holds a respectable position at the ranch, but he still defers to Slim’s authority as the ranch’s de facto leader and to Curley’s authority as the boss’s son, although he deeply dislikes him. Carlson’s treatment of Candy’s dog shows him to be a pragmatic man who, although not unnecessarily violent like Curley, has been desensitized to violence and is emotionally detached from the injuries, hardships, and deaths that plague ranch life. Carlson believes that putting down a blind, lame dog that is no longer of use is the sensible thing to do, but he is insensitive to the fact that Candy views the dog as a beloved companion, not just a work dog. Although Carlson treats the dog gently and promises a painless death, his insistence on killing it is motivated by selfishness – he’s bothered by the dog’s smell – and suggests that he lacks a degree of empathy for the feelings of his fellow ranch hands.
Although not actively aggressive or mean-spirited, Carlson is resigned to the hard, hierarchical nature of the world of ranching. He uses his relative power as an advantage when he can, such as when he bullies Candy, who is lower on the ranch’s hierarchy due to his age, into shooting the dog. It may be that Carlson’s unsentimental personality is a survival mechanism that allows him to live on the ranch without having painful emotional reactions to his own suffering or the suffering of his peers. Carlson has accepted that the removal of the weak or old and the survival of the strong are immutable characteristics of the world he inhabits, and that he must abide by those rules in order to survive. At the end of Of Mice and Men, when George is being comforted by Slim after killing Lennie, Carlson voices the novel’s iconic final line: “Now what the hell ya suppose is eatin’ them two guys?” His confusion shows that he doesn’t have the empathy or emotional capacity to understand the tragedy of Lennie’s death or the horror of George being responsible for executing his lifelong friend.