In the absence of a narrator in Death of a Salesman, what devices does Miller use to provide exposition—basic information about character and setting?
Miller uses some very straight-forward methods of exposition along with some savvy authorial devices to provide exposition on character and setting.
The primary mode of exposition for setting and character is dialogue taking place in the "present moment" of the play. At the opening of the play, Willy and Linda discuss their house and the state it is in, commenting also on their financial situation. They also discuss their son, introducing his persona as well as his character's themes. This conversation is an example of indirect exposition that borders on direct exposition as the characters flesh out the context of their lives to open the play.
Additionally, with several characters of the play nearing a crisis point in their lives and relationships, reflection on the path taken through life that has led to this crisis is natural. The characters are able to talk about their past, their dreams, and their failures in a dramatic context that naturally calls for such discussions. Developing a dramatic context that allows for reflection is one of the most subtle (and significant) modes of exposition Miller uses in the play.
Perhaps the most obvious devices used in the play are the use of flashback and the "voice of conscience" character - Willy's brother Ben.
Flashback scenes highlight Willie's relationship to Biff, allowing the audience to see both Biff's devotion to Willy, Willy's faith in Biff, and the critical episode that strained this relationship to a breaking point.
Willy's brother Ben, while not literally the voice of conscience for Willy, none-the-less fits the mode of this type of character. Not a good angel on his shoulder and not exactly a "pure" hallucination, Ben represents a combination of Willy's ambition, his mental weakness, and his actual memory.
Ben's character allows for the expression of Willy's dementia as a manifestation of his failure to live up to a very specific and impossible dream.
Willy's dementia is another subtle tool that allows for exposition of the past, further developing various aspects of his character:
Willy reminisces about past events and imagines situations, and the audience is able to see his thoughts played out on the stage.
Ben stands as the embodiment of these reminiscences. His stature and success are a stark contrast to Willy's humiliated state of failure. We see this articulation near the end of the play, when Willy speaks to Ben about his suicide plan, defending the act.
"Why? Does it take more guts to stand here the rest of my life ringing up a zero? ... And twenty thousand—that is something one can feel with the hand, it is there."
In this discussion, the themes of Willy's troubles become perfectly clear.