In A Separate Peace, how does Finny theorize that the war is not real? Why do you think he came up with this theory? How does he perpetuate his idea?

In A Separate Peace, Finny loves to
do what he can't or isn't supposed to do.  He wears a tie for a belt then makes up a
preposterous reason for doing so, and manages to talk and rationalize his way out of
it.  He breaks the swimming record because the record exists and no one else has, and
because he isn't a swimmer so he's not supposed to be able to break
it.

Finny shows no interest in going to war before his
"accident," but once he's crippled and can't go, then he wants to.  Joining the military
becomes an obsession for him.  Why?  Because he can't. 

He
perpetuates the myth that there is no war, the same way he got out of using a tie for a
belt:  creating preposterous rationalizations to prove the war is a fake, and repeating
them and adding to them whenever the subject comes
up. 

Only after he has allowed himself the destruction of
his illusions, only after he admits to himself that Gene purposely jounced him out of
the tree, does Finny admit the truth about his failed attempts to
enlist.