In "Death of a Salesman," why did Willy think it was ok for his son, Biff, to steal the balls?

One of
the characteristics that makes Willy Loman a classically tragic figure is his consistent state
of denial. He is in denial about so many things; his failure as a salesman, the unhappiness of
his family, his own weaknesses. His unwillingness to see Biff's criminal behavior for what it
is, is a part of that denial and helps to bolster 's theme of the degradation of American
society due to the relentless pressure on the middle class to succeed.