Willy Loman's idea of the American dream is focused...
on appearances. Look good, be personable, and make friends. Willy believes that any man who does those things deserves to achieve the American dream and will naturally accomplish it:
WILLY: Bernard is not well liked, is he?
BIFF: He’s liked, but he’s not well liked.
HAPPY: That’s right, Pop.
WILLY: That’s just what I mean. Bernard can get the best marks in school, y’understand, but when he gets out in the business world, y’understand, you are going to be five times ahead of him. That’s why I thank Almighty God you’re both built like Adonises. Because the man who makes an appearance in the business world, the man who creates personal interest, is the man who gets ahead. Be liked and you will never want.
Now in his sixties, Willy comes home with his heavy sample cases after what was supposed to be a sales trip to upper New England, but he couldn't get past Yonkers, a suburb of New York City just above the Bronx. After thirty-six years on the road, Willy is exhausted in body and spirit.
His wife, Linda, gets up from bed to meet him:
WILLY. I’m tired to the death....I couldn’t make it. I just couldn’t make it, Linda.
Throughout the play, Willy questions what brought him to this point in his life. He searches desperately for the moments when his life went wrong—when he went off the path on his way to the American dream.
He has flashbacks to moments he can remember when he thinks he might have gone wrong: for example, when he betrayed his relationship with his wife and destroyed his relationship with his son, Biff, without even realizing what he was doing.
Willy simply didn't understand that it wasn't individual circumstances that denied him the American dream. It was his own choices, his own mistakes. Willy failed himself.
Willy was hoping that even if he couldn't accomplish the American dream, his sons Happy and Biff could achieve it for him, but they failed as well, leaving Willy with no dream at all. The American dream slipped through Willy's fingers, and he had no idea how or why it happened, and he simply lost faith in himself and in the dream:
CHARLEY: It was a very nice funeral....
LINDA: I can’t understand it. At this time especially. First time in thirty-five years we were just about free and clear. He only needed a little salary. He was even finished with the dentist.
CHARLEY: No man only needs a little salary.
LINDA: I can’t understand it....
BIFF: He had the wrong dreams. All, all, wrong.
HAPPY. Don’t say that!
BIFF. He never knew who he was.
CHARLEY....You don’t understand: Willy was a salesman. And for a salesman, there is no rock bottom to the life....He’s a man way out there in the blue, riding on a smile and a shoeshine. And when they start not smiling back—that’s an earthquake. And then you get yourself a couple of spots on your hat, and you’re finished....A salesman is got to dream, boy. It comes with the territory.
Biff doesn't subscribe to Charley's romanticized version of Willy's life:
BIFF: Charley, the man didn’t know who he was.
Willy came to realize who he was too late and that his failure to acquire the American dream was his own fault. He made wrong choices, and those choices sidetracked him, wasted his time and energy, and took him off the path toward the American dream:
WILLY. Funny, y'know? After all the highways, and the trains, and the appointments, and the years, you end up worth more dead than alive.
Figuratively and literally, Willy Loman killed himself to make money.
Arthur Miller doesn't attack the American dream, as such. He simply questions it. He questions if it necessarily applies to everyone or if it's reasonable for everyone to try to achieve it. He also questions the objective of the American dream, which is the acquisition of material wealth.
Willy's mistake—the tragic flaw of a modern tragic hero—is that he valued the American dream above everything else and pursued it at all costs. The decisions Willy made in deference to the American dream destroyed his relationships with his wife and with his sons, and they ultimately destroyed his own life.