After his injury, the once "gung-ho-for-the-war" Finny tells Gene and Brinker that the war is simply a ploy designed by fat old men to do away with their competition (young men) by sending them into combat. He even asks Gene,
" 'Have you swallowed all that war stuff?' " (114).
When Finny first verbalizes his theory, Gene does not understand why Finny would have so drastically changed his attitude toward the war. However, after Finny is injured yet again, Gene discovers that Finny's disillusionment from the war stems from Finny's not being able to participate in the war effort. He had been writing military leaders from all around the world to see if anyone would accept him.
When Finny breaks his leg he thinks that the fat old men were creating stuff about the war and when Finny didn't break his leg he wanted to enlist with gene after the war
Finny actually does not change his attitude about war until he sees how leper has changed drastically from when he returned.