What is the main idea of the play All My Sons by Arthur Miller? By that I mean what is the play about in one sentence or the core of the play.

We might summarize the comment the play is making in a
number of ways. One way to phrase the "core" of the play is to say "Miller's play
suggests that those aware of the truth are responsible for
it". 

We see this notion carried out as Chris and Ann
remain aloof regarding the truth about the faulty airplane parts, perhaps purposefully,
and so remove themselves from responsibility for most of the
play.

Kate, Joe and George, however, are all aware of the
truth and so also are driven and defined by it. In the end, all the characters become
both responsive and responsible for the truth and its
consequences. 

readability="11">

The revelations that lead up to Joe's tragic
recognition of guilt and his suicide, the final consequences of his choice, are
essential to All My Sons. There is a sense
of anake, or tragic necessity, that moves the work along towards
its inevitable moment of truth and awful but final
retribution.

Other
articulations of the play's core might
be: 

• "Relationships are
  tested according to their honesty." 


• "Moral
  responsibility is socially defined and socially enforced, but individually
  felt." 


• "Ultimately, one cannot escape the
  truth."