In A Separate Peace, what is Finny's theory about the war? How did his injury affect his feelings toward the war?

Gene's flashback begins in the summer of 1942, about six months after the United States entered World War II with the bombing of Pearl Harbor. The boys in the summer session at Devon are very aware of the war that waits for them after graduation. Finny is among them. However, after Finny breaks his leg in falling from the tree and as the school year wears on, he assumes a different attitude toward the war, declaring that there is no war at all. According to Finny, the war is a fake, a plot by the "fat old men" of the world to secure for themselves the best of everything that is being rationed for everyone else. Thus begins Finny's denial of the reality of World War II.

In keeping this illusion alive, he draws Gene into it. Finny tells Gene that since Finny can't participate in the Olympics of 1944, he will train Gene to take his place. The training begins during the winter. There will be no 1944 Olympics, of course, because of the war, but both boys work hard to keep Finny's illusion alive and reality at bay.

At the conclusion of the story, it is revealed that all the while he had been denying the reality of the war, Finny had been writing to every branch of armed services in the allied world, trying to find one that would accept him despite his injured leg. No military service would accept him, however. Finny couldn't stand that all his friends and school companions would go off to war, leaving him behind. He told Gene, "I will hate it everywhere" if he were left out, unable to participate.

Finny gives up his pretense that the war does not exist when Leper returns to Devon after deserting the Army. The psychological damage done to Leper in boot camp makes it impossible for him to continue the illusion. Gene relents, also, but he tells Finny he liked the world they had lived in better than the real one.