Hemingway was a big drinker, and so are most of his characters; some are so-called "good" drunks, while others are "bad" ones. What, you may ask, is a "good" drunk in Hemingway's experienced opinion? Basically, it's someone who can hold his or her liquor and retain some dignity, even when he/she's totally plastered. The real question is, why do Hemingway's characters need to be drunk all the time, however they handle it? There's a wide variety of possible answers to this question, but the best one is the most obvious: Hemingway's characters drink to escape from everyday life. "A Clean, Well-Lighted Place" is no exception – here, one of the characters drinks every night to escape from himself and his loneliness.
Alcohol serves as an anesthetic in "A Clean, Well-Lighted Place," allowing the old man to dull the pain of a meaningless existence.
Drinking at a café, in Hemingway's story, is a way of participating in society, even if one drinks alone there.